My Notes for AWS Solutions Architect SAA-01 Exam

13 Oct 2019

Services

IAM

Role: Can be associated with resources like EC2/Cloudformation. Or assumed by user when they’re using Federation, SAML.

User: User with access key, secret key and password.

Group: Group of users

Policy

Permissions for groups of users or roles. Policy can be of two types: Permission Policy and Permission Boundary. Permission Policy is permissions which are assigned to user or resource. This includes identity based, resource based and ACLs. Permission Boundary is for max permissions an object can have,

To access resources in own account we need identity based policies. For cross account permissions we need resource based policies.

By default all requests are denied. If there’s allow, then it’s allowed. Permission Boundary overrides allow. An explicit deny anywhere overrides allow.

Exam tips

IAM is eventually consistent.

What is web identity federation?

Web identity federation allows you to create AWS-powered mobile apps that use public identity providers (such as Amazon Cognito, Login with Amazon, Facebook, Google, or any OpenID Connect-compatible provider) for authentication

Organizations

AWS Organizations offers policy-based management for multiple AWS accounts. With Organizations, you can create groups of accounts, automate account creation, apply and manage policies for those groups. Organization enables you to centrally manage policies across multiple accounts, without requiring custom scripts and manual processes. Using AWS Organizations, you can create Service Control Policies (SCPs) that centrally control AWS service use across multiple AWS accounts. You can also use Organizations to help automate the creation of new accounts through APIs. Organization helps simplify the billing for multiple accounts by enabling you to set up a single payment method for all the accounts in your organization through consolidated billing. AWS Organizations is available to all AWS customers at no additional charge.

Difference between a service control policy and an IAM policy?

AWS Organizations lets you use service control policies (SCPs) to allow or deny access to particular AWS services for individual AWS accounts, or for groups of accounts within an organizational unit (OU). The specified actions from an attached SCP affect all IAM users, groups, and roles for an account, including the root account identity.

When you apply an SCP to an OU or an individual AWS account, you choose to either enable (whitelist), or disable (blacklist) the specified AWS service. Access to any service that isn’t explicitly allowed by the SCPs associated with an account, its parent OUs, or the master account is denied to the AWS accounts or OUs associated with the SCP.

When an SCP is applied to an OU, it is inherited by all of the AWS accounts in that OU.

IAM policies let you allow or deny access to AWS services (such as Amazon S3), individual AWS resources (such as a specific S3 bucket), or individual API actions (such as s3:CreateBucket). An IAM policy can be applied only to IAM users, groups, or roles, and it can never restrict the root identity of the AWS account.

Web Identity Federation and Cognito

Cognito gives web identity federation service in AWS. It allows you to sign in and sign up. Acts as broker so you don’t need to write code. Synchronizes data between different devices. Recommended for all mobile applications. It maps a role from open id to AWS IAM Role and gives temporary access to resources

AWS supports identity federation with SAML 2.0, an open standard that many identity providers (IdPs) use. This feature enables federated single sign-on (SSO), so users can log into the AWS Management Console or call the AWS APIs without you having to create an IAM user for everyone in your organization. By using SAML, you can simplify the process of configuring federation with AWS, because you can use the IDP service instead of writing custom identity proxy code.

Option 1 is incorrect because web identity federation is primarily used to let users sign in via a well-known external identity provider (IdP), such as Login with Amazon, Facebook, Google. It does not utilize Active Directory.

Cognito

When it comes to mobile and web apps, you can use Amazon Cognito so that you don’t have to manage a back-end solution to handle user authentication, network state, storage, and sync. Amazon Cognito generates unique identifiers for your users. Those identifiers can be referenced in your access policies to enable or restrict access to other AWS resources on a per-user basis. Amazon Cognito provides temporary AWS credentials to your users, allowing the mobile application running on the device to interact directly with AWS Identity and Access Management (IAM)-protected AWS services. For example, using IAM you can restrict access to a folder in an S3 bucket to a particular end user.

User Pool

User pools are used for users logging in. Successful auth generates JWT. Users can also login directly in User Pools.

Say you were creating a new web or mobile app and you were thinking about how to handle user registration, authentication, and account recovery. This is where Cognito User Pools would come in. Cognito User Pool handles all of this and as a developer you just need to use the SDK to retrieve user related information.

Identity Pool

Identity pools provide temporary access to AWS resources.

Cognito monitors different devices you use. It then uses SNS to push updates to all devices.

Cognito Identity Pool (or Cognito Federated Identities) on the other hand is a way to authorize your users to use the various AWS services. Say you wanted to allow a user to have access to your S3 bucket so that they could upload a file; you could specify that while creating an Identity Pool. And to create these levels of access, the Identity Pool has its own concept of an identity (or user). The source of these identities (or users) could be a Cognito User Pool or even Facebook or Google.

AWS Directory Service

• AWS Managed Microsoft AD is best for current AD or LDAP
• Deployed to two AZ and connected to your VPC
• Fully managed, no access to powershell or ssh/rdp.
• A VPC with at least 2 subnets required
• Seamless domain join can be used for connecting EC2 instance to your AD at launch time
• Trust relationship to sync between on premise and AWS AD

Simple AD

Fully managed, mini AD with smaller feature set but good for use when needed for simple AD features. Based on Samba 4. Does not have MFA, Trust Relations, Powershell cmdlets.

Amazon Cloud Directory

Allows storage of hierarchical objects with relations and schema. Can organize in multiple hierarchies.

AD Connector

Helps connect existing AD on premise to AWS

Exam Tips

• Service Accounts = Roles. No federation even if it’s on premises.
• IAM trust policy allows EC2 instances to assume a role
• IAM policy or S3 Bucket policy allows get/put from buckets in S3. Note: No S3 Trust Policy. Also IAM trust policy is required but it’s not required for S3.
• IAM Certificate Store and Certificate Manager let you manage SSL certs

References

https://tutorialsdojo.com/aws-cheat-sheet-aws-identity-and-access-management-iam/

https://tutorialsdojo.com/aws-cheat-sheet-aws-directory-service/

http://jayendrapatil.com/aws-iam-overview/ 

https://docs.aws.amazon.com/autoscaling/ec2/userguide/control-access-using-iam.html 

https://aws.amazon.com/premiumsupport/knowledge-center/iam-policy-service-control-policy/

https://aws.amazon.com/organizations/getting-started/ 

https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_policies_scp.html

S3

Buckets

• Name must be unique globally
• Can create 100 buckets in one account.
• Can’t change region or name once created
• Fomat: Host Style: http://bucket.s3-aws-region.amazonaws.com
• Format: Path Style: http://s3-aws-region.amazonaws.com/bucket 

Consistency

• Read After Write for new PUTS
• Eventual for overwrite PUTS and DELETES in all regions

Storage Classes

S3 Standard: For general purpose. Highly redundant and available 99.99% of the time. Durability: 11 9s.

S3 RRS: Reduced redundancy but not recommended because S3 Standard is cheaper.

S3 IA: Infrequently Accessed Data. Available 99.9%

S3 IA One Zone: Same as S3 IA but redundancy only in one AZ. Available 99.5%. Durable 11 9s but in one Zone.

These two are good for objects that are more than 128 KB and can be stored for a minimum of 30 days. Otherwise Amazon charges you for one month and 128 KB.

Glacier: For archival. Can not specify glacier at object creation time. Must use lifecycle transition with 0 days to immediately transition. Must be at least 6 months storage. That’s what AWS charges for minimum.

Glacier Retrieval Options:

Expedited: Available within 1-5 Minutes

Standard: Retrieves within 3-5 hours

Bulk: Within 5-12 hours.

Minimum 3 AZ used for standard,d IA and glacier.

Transfer Acceleration

Transfer Acceleration enables fast, easy, and secure transfers of files over long distances between your client and an S3 bucket. It takes advantage of Amazon CloudFront’s globally distributed edge locations.

Transfer Acceleration cannot be disabled, and can only be suspended.

Objects

• You can upload and copy objects of up to 5 GB in size in a single operation. For objects greater than 5 GB up to 5 TB, you must use the multipart upload API
• You can associate up to 10 tags with an object. Tags associated with an object must have unique tag keys.

Security

Bucket Policies

• Provides centralized access control to buckets and objects based on a variety of conditions, including S3 operations, requesters, resources, and aspects of the request (e.g., IP address).
• Can either add or deny permissions across all (or a subset) of objects within a bucket.
• IAM users need additional permissions from root account to perform bucket operations.
• Bucket policies are limited to 20 KB in size.
• Can restrict based on time of day, CIDR block range, and by IP address.

Access Control Lists

• A list of grants identifying grantee and permission granted.
• ACLs use an S3–specific XML schema.
• You can grant permissions only to other AWS accounts, not to users in your account.
• You cannot grant conditional permissions, nor explicitly deny permissions.
• Object ACLs are limited to 100 granted permissions per ACL.
• The only recommended use case for the bucket ACL is to grant write permissions to the S3 Log Delivery group

Versioning

• Need to explicitly enable it
• When you delete, a  delete marker is created
• Can’t disable versioning
• Can enable MFA delete

Notifications

Can notify on create/delete or loss of object in RRS to following:

• SNS
• SQS
• Lambda

Cross Region Replication

• Both source and destination buckets must have versioning enabled.
• S3 must have permissions to replicate objects from the source bucket to the destination bucket on your behalf.
• If the owner of the source bucket doesn’t own the object in the bucket, the object owner must grant the bucket owner READ and READ_ACP permissions with the object ACL.
• Only copies Objects created after you add a replication configuration.
• Objects created with server-side encryption using customer-provided (SSE-C) encryption keys are not replicated
• Objects created with server-side encryption using AWS KMS–managed encryption (SSE-KMS) keys are not replicated by default. You must enable it.
• You can replicate objects from a source bucket to only one destination bucket.
• Deletes are not replicated. You must delete versions in both regions. A delete marker is replicated.

Encryption

• Server-side Encryption using

• Amazon S3-Managed Keys (SSE-S3)
• AWS KMS-Managed Keys (SSE-KMS)
• Customer-Provided Keys (SSE-C)

• Client-side Encryption using

• AWS KMS-managed customer master key
• client-side master key
• S3 supports either S3 supplied encryption key or client provided encryption key. For Client provided, user must send encryption key for each API call. S3 never stores client provided key.

Exam Tips

• Objects in S3 are stored in different partitions based on name from left to right. To improve performance add random characters at the start of object name to put it in different partitions to improve performance.
• Domain used for s3 bucket: amazonaws.com
• http://mynewbucket.s3-aws-region.amazonaws.com 
• http://s3-aws-region.amazonaws.com/mynewbucket 
• Headers have x-amz-* headers. Note: no x-aws
• Here are the prerequisites for routing traffic to a website that is hosted in an Amazon S3 Bucket:
• • An S3 bucket that is configured to host a static website. The bucket must have the same name as your domain or subdomain. For example, if you want to use the subdomain portal.tutorialsdojo.com, the name of the bucket must be portal.tutorialsdojo.com.
• • A registered domain name. You can use Route 53 as your domain registrar, or you can use a different registrar.
• • Route 53 as the DNS service for the domain. If you register your domain name by using Route 53, we automatically configure Route 53 as the DNS service for the domain.

• Objects must be stored at least 30 days in the current storage class before you can transition them to STANDARD_IA or ONEZONE_IA. For example, you cannot create a lifecycle rule to transition objects to the STANDARD_IA storage class one day after you create them. Amazon S3 doesn’t transition objects within the first 30 days because newer objects are often accessed more frequently or deleted sooner than is suitable for STANDARD_IA or ONEZONE_IA storage.
• If you are transitioning noncurrent objects (in versioned buckets), you can transition only objects that are at least 30 days noncurrent to STANDARD_IA or ONEZONE_IA storage.

References

A Cloud Guru — S3 Masterclass https://acloud.guru/learn/s3-masterclass 

https://tutorialsdojo.com/aws-cheat-sheet-amazon-s3/ 

https://docs.aws.amazon.com/AmazonS3/latest/dev/ObjectVersioning.html

https://docs.aws.amazon.com/AmazonS3/latest/dev/crr-what-is-isnot-replicated.html 

https://aws.amazon.com/solutions/cross-region-replication-monitor/ 

https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region 

https://docs.aws.amazon.com/AmazonS3/latest/dev/crr-add-config.html 

Cloudfront

• CDN service for Amazon
• Uses Edge Locations
• When user request comes, it serves from lowest latency edge location
• Cloudfront distribution is for telling cloudfront which origin servers to fetch objects from and whether it should be enabled as soon as it’s creation. A distribution is then sent to all edge locations.
• You can use lambda@edge to modify content at edge location and perform different operations.
• Can use signed URLs or signed cookies
• Cloudfront origin group can be used for origin failover. You can choose a combination of HTTP 4xx/5xx status codes that, when returned from the primary origin, trigger the failover to the backup origin.
• Cached for 24 hours by default but you can invalidate. Invalidation has charges. First 1000 invalidations are free.
• It’s a global service so to enable logs in Cloudtrail you must enable global services
• With origin access identity feature you can restrict access to S3 so it would only be accessible from cloudfront.
• Field Level Encryption allows users to upload sensitive info like cc numbers to your origin securely with cloudfront.
• Max file size that can be served is 20 GB.
• Can use zone APEX with help of route 53 Alias record.
• You can integrate your CloudFront distribution with AWS WAF, a web application firewall that helps protect web applications from attacks by allowing you to configure rules based on IP addresses, HTTP headers, and custom URI strings. Using these rules, AWS WAF can block, allow, or monitor (count) web requests for your web application. Please see AWS WAF Developer Guide for more information.
• S3 Transfer acceleration can be used to upload faster using cloudfront edge locations
• Signed URLs and Signed Cookies can be used for temporary access to cloudfront urls
• OAI: Origin access identity so users can’t access S3 bucket directly. They can only do so via cloudfront.
• You have to use an Application Load Balancer instead or a CloudFront web distribution to allow the SNI feature.

https://tutorialsdojo.com/aws-cheat-sheet-amazon-cloudfront/

https://s3-accelerate-speedtest.s3-accelerate.amazonaws.com/en/accelerate-speed-comparsion.html 

https://tutorialsdojo.com/aws-cheat-sheet-s3-pre-signed-urls-vs-cloudfront-signed-urls-vs-origin-access-identity-oai/ 

https://aws.amazon.com/cloudfront/features/ 

https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/PrivateContent.html 

https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-signed-urls.html 

https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-signed-cookies.html 

https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-restricting-access-to-s3.html 

AWS Shield

•  AWS Shield Standard is free of cost
• Enterprise is cool but needs business support contract. Also gives you access to DDoS response team.

https://tutorialsdojo.com/aws-cheat-sheet-aws-shield/

Storage Gateway

AWS Storage Gateway AWS Storage Gateway is a hybrid storage service that enables your on-

premises applications to seamlessly use AWS cloud storage. You can use the service for backup and archiving, disaster recovery, cloud data processing, storage tiering, and migration. Your applications connect to the service through a virtual machine or hardware gateway appliance using standard storage protocols, such as NFS, SMB and iSCSI. The gateway connects to AWS storage services, such as Amazon S3, Amazon Glacier, and Amazon EBS,

providing storage for files, volumes, and virtual tapes in AWS. The service includes a highly-optimized data transfer mechanism, with bandwidth management, automated network resilience, and efficient data transfer, along with a local cache for low-latency on-premises access to your most active data.

The service stores files as native S3 objects, archives virtual tapes in Amazon Glacier, and stores EBS Snapshots generated by the Volume Gateway with Amazon EBS.

File Gateway

Supports a file interface into S3 and combines a service and a virtual software appliance.

With a file gateway, you can do the following:

• You can store and retrieve files directly using the NFS version 3 or 4.1 protocol.
• You can store and retrieve files directly using the SMB file system version, 2 and 3 protocol.
• You can access your data directly in S3 from any AWS Cloud application or service.
• You can manage your S3 data using lifecycle policies, cross-region replication, and versioning.

File Gateway now supports Amazon S3 Object Lock, enabling write-once-read-many (WORM) file-based systems to store and access objects in Amazon S3.

Any modifications such as file edits, deletes or renames from the gateway’s NFS or SMB clients are stored as new versions of the object, without overwriting or deleting previous versions.

Gateway-Cached and File Gateway volumes retain a copy of frequently accessed data subsets locally

Volume Gateway

Provides cloud-backed storage volumes that you can mount as iSCSI devices from your on-premises application servers.

Cached volumes

You store your data in S3 and retain a copy of frequently accessed data subsets locally. Cached volumes can range from 1 GiB to 32 TiB in size and must be rounded to the nearest GiB. Each gateway configured for cached volumes can support up to 32 volumes

Stored volumes

If you need low-latency access to your entire dataset, first configure your on-premises gateway to store all your data locally. Then asynchronously back up point-in-time snapshots of this data to S3.

Tape Gateway

Archive backup data in Amazon Glacier. Has a virtual tape library (VTL) interface to store data on virtual tape cartridges that you create. Deploy your gateway on an EC2 instance to provision iSCSI storage volumes in AWS.

References

https://tutorialsdojo.com/aws-storage-gateway/ 

https://aws.amazon.com/storagegateway/faqs/ 

EBS

• New EBS volumes receive their maximum performance the moment that they are available and do not require initialization (formerly known as pre-warming). However, storage blocks on volumes that were restored from snapshots must be initialized (pulled down from Amazon S3 and written to the volume) before you can access the block.
• Termination protection is turned off by default and must be manually enabled (keeps the volume/data when the instance is terminated)
• Different types of storage options: General Purpose SSD (gp2), Provisioned IOPS SSD (io1), Throughput Optimized HDD (st1), and Cold HDD (sc1) volumes up to 16 TiB in size.
• Volumes are created in a specific AZ, and can then be attached to any instances in that same AZ. To make a volume available outside of the AZ, you can create a snapshot and restore that snapshot to a new volume anywhere in that region.
• You can detach an EBS volume from an instance explicitly or by terminating the instance. However, if the instance is running, you must first unmount the volume from the instance.
• You can use AWS Backup, an automated and centralized backup service, to protect EBS volumes and your other AWS resources. AWS Backup is integrated with Amazon DynamoDB, Amazon EBS, Amazon RDS, Amazon EFS, and AWS Storage Gateway to give you a fully managed AWS backup solution.

Types of EBS Volumes

General Purpose SSD (gp2)

• Base performance of 3 IOPS/GiB, with the ability to burst to 3,000 IOPS for extended periods of time.
• Support up to 10,000 IOPS and 160 MB/s of throughput.

Provisioned IOPS SSD (io1)

• Designed for I/O-intensive workloads, particularly database workloads, which are sensitive to storage performance and consistency.
• Allows you to specify a consistent IOPS rate when you create the volume
• Max IOPS: 32000

An io1 volume can range in size from 4 GiB to 16 TiB. You can provision from 100 IOPS up to 64,000 IOPS per volume on Nitro system instance families and up to 32,000 on other instance families. The maximum ratio of provisioned IOPS to requested volume size (in GiB) is 50:1.

For example, a 100 GiB volume can be provisioned with up to 5,000 IOPS. On a supported instance type, any volume 1,280 GiB in size or greater allows provisioning up to the 64,000 IOPS maximum (50 × 1,280 GiB = 64,000).

An io1 volume provisioned with up to 32,000 IOPS supports a maximum I/O size of 256 KiB and yields as much as 500 MiB/s of throughput. With the I/O size at the maximum, peak throughput is reached at 2,000 IOPS. A volume provisioned with more than 32,000 IOPS (up to the cap of 64,000 IOPS) supports a maximum I/O size of 16 KiB and yields as much as 1,000 MiB/s of throughput.

Therefore, for instance, a 10 GiB volume can be provisioned with up to 500 IOPS. Any volume 640 GiB in size or greater allows provisioning up to a maximum of 32,000 IOPS (50 × 640 GiB = 32,000).

Throughput Optimized HDD (st1)

• Low-cost magnetic storage that focuses on throughput rather than IOPS.
• Throughput of up to 500 MiB/s.

Cold HDD (sc1)

• Low-cost magnetic storage that focuses on throughput rather than IOPS.
• Throughput of up to 250 MiB/s.

Monitoring

• Volume status checks provide you the information that you need to determine whether your EBS volumes are impaired, and help you control how a potentially inconsistent volume is handled. List of statuses include:

• Ok – normal volume
• Warning – degraded volume
• Impaired – stalled volume
• Insufficient-data –  insufficient data

RAID

Some EC2 instance types can drive more I/O throughput than what you can provision for a single EBS volume. You can join multiple gp2, io1, st1, or sc1 volumes together in a RAID 0 configuration to use the available bandwidth for these instances.

For greater I/O performance than you can achieve with a single volume, RAID 0 can stripe multiple volumes together; for on-instance redundancy, RAID 1 can mirror two volumes together.

Creating Snapshots of Volumes in a RAID Array

If you want to back up the data on the EBS volumes in a RAID array using snapshots, you must ensure that the snapshots are consistent. This is because the snapshots of these volumes are created independently. To restore EBS volumes in a RAID array from snapshots that are out of sync would degrade the integrity of the array.

To create a consistent set of snapshots for your RAID array, use EBS multi-volume snapshots. Multi-volume snapshots allow you to take point-in-time, data coordinated, and crash-consistent snapshots across multiple EBS volumes attached to an EC2 instance. You do not have to stop your instance to coordinate between volumes to ensure consistency because snapshots are automatically taken across multiple EBS volumes.

Amazon DLM

You can use Amazon Data Lifecycle Manager (Amazon DLM) to automate the creation, retention, and deletion of snapshots taken to back up your Amazon EBS volumes.

Exam Tips

Take note that HVM AMIs are required to take advantage of enhanced networking and GPU processing.

Although the Enhanced Networking feature can provide higher I/O performance and lower CPU utilization to your EC2 instance, you have to use an HVM AMI instead of PV AMI.

You can perform live migration as long as instance root volume is EBS. Instance store can’t migrate.

Decreasing the size of an EBS volume is not supported.

To attach volume attached in one instance to other, detach and attach to other.

Instance Type = hardware capacity. Instance type has memory, cpu and storage. OS and software loaded is decided by AMI

Max Volume Size for magnetic tape = 1 TB. for SSD it’s 16 TB.

Instance started with EBS is faster than instance store. Instance store requires all parts retrieved from S3. EBS only requires stuff for boot before instance is available.

To avoid initial performance we must warm up volume by reading all blocks

when you create an EBS volume in an Availability Zone, it is automatically replicated within that zone only to prevent data loss due to a failure of any single hardware component. After you create a volume, you can attach it to any EC2 instance in the same Availability Zone. Note: EBS is single AZ and can tolerate hardware failures but not AZ failure.

Encryption

encrypt root volumes:

• take snapshot

• copy snapshot and encrypt

• create image of snapshot

• then launch ami

• can encrypt at startup

• can share only if volume is unencrypted

There is no direct way to encrypt an existing unencrypted volume, or to remove encryption from an encrypted volume. However, you can migrate data between encrypted and unencrypted volumes.

References

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/raid-config.html#ebs-snapshots-raid-array 

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-creating-snapshot.html 

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/raid-config.html 

https://tutorialsdojo.com/aws-cheat-sheet-amazon-ebs/ 

https://aws.amazon.com/blogs/aws/new-infrequent-access-storage-class-for-amazon-elastic-file-system-efs/ 

https://docs.aws.amazon.com/efs/latest/ug/limits.html 

EFS

• NFS share mount
• Can be mounted to multiple EC2 instances unlike EBS which can only be used on one at a time
• Stores data in Multi AZ
• Can mount to on-premise using Direct Connect and VPN
• To access your EFS file system in a VPC, you create one or more mount targets in the VPC. A mount target provides an IP address for an NFSv4 endpoint.
• You can create one mount target in each Availability Zone in a region.
• You mount your file system using its DNS name, which will resolve to the IP address of the EFS mount target. Format of DNS is
  File-system-id.efs.aws-region.amazonaws.com
• Up to thousands of EC2 instances, from multiple AZs, can connect concurrently to a file system.
• On Windows, can’t be mounted as drive. But can be mounted as folder.

Exam Tips

• EFS != S3. Don’t select EFS when asked for S3 enabled service.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-efs/ 

https://tutorialsdojo.com/aws-cheat-sheet-amazon-s3-vs-ebs-vs-efs/

EC2

Exam tips

• Pricing only for Spot, On demand and Reserved instances. No Dedicated.
• If instance shutdown behavior is set to terminate, then instance will terminate regardless of whether termination protection is on.
• EC2 items to monitor

• CPU utilization, Network utilization, Disk performance, Disk Reads/Writes using EC2 metrics
• Memory utilization, disk swap utilization, disk space utilization, page file utilization, log collection using a monitoring agent/CloudWatch Logs

• You can pass two types of user data to EC2: shell scripts and cloud-init directives.
• User data is limited to 16 KB.
• If you stop an instance, modify its user data, and start the instance, the updated user data is not executed when you start the instance.
• Retrieve user data from within a running instance at http://169.254.169.254/latest/user-data
• AMI = hardware type + OS. Notice: No Licenses
• Instance Type = Storage + CPU + Memory
• When user receives InsufficientInstanceCapacity Error, while launching Ec2, it means that AWS does not currently have enough available capacity to service user request. User can try later or use different AZ.
• Stopping and Starting instance fixes status checker errors because unless you have dedicated instance, it usually starts on a different AWS hardware.
• EC2 is limited to 20 instances for new accounts. Use form for increasing.
• Keep Spot instances primary and on demand secondary. On demand only provision when the spot are gone to save costs.

Instance Types

On Demand

fix rate by hour or second

Reserved

contract terms 1 or 3 years. provides discount and capacity reservation

Spot

Bid on instance capacity. Greater saving for when there’s no fix start or end time.

not charged if it’s terminated in partial hour by AWS. But if you terminate it, you will be charged

Dedicated Host

Can help in using server based license or regulation saying you cant use virtualization

Three tenancy options:

Dedicated Instance

Shared Tenancy

Dedicated Host

Security Groups

• security group changes are effective immediately

• security groups are stateful i.e outbound and inbound rules apply

• ACLs are stateless they need to be added for both inbound and outbound traffic

• can attach one or more security groups to an instance

• all inbound is blocked

• all outbound is allowed

• Can’t block specific IP addresses. Need to use ACLs to do that

• You can allow rules but can’t deny rules using security groups

roles are easier to manage and dont store on ec2

are recommended instead of using access key and secret key

roles are universal

instance store is ephemeral storage. You cant stop Instance Store volumes, you lose data when it terminates

meta data is available on 169.254.169.254/latest/meta-data or /user-data

EFS: shared file system between ec2 instances. Can grow based on usage. Supports NFSv4. Need to configure security groups between instances and EFS volume.

EC2 Placement groups

Exam tip: Use enhanced networking instances for placement groups

Clustered group all instances in one rack

Low network latency high throughput

cant be in multiple AZ

recommended same instance types

Spread group put all instances in different racks

individual crtical instances

can be in multiple AZ

Partitioned group mix of above two. Put N instances on one rack and N on other

can be in multiple AZ

can’t merge placement groups and can’t move existing instance to placement group. You can create AMI and then launch instance in placement group

HDFS/HFS/Cassandra

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-elastic-compute-cloud-amazon-ec2/ 

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/building-shared-amis.html 

https://aws.amazon.com/blogs/security/new-attach-an-aws-iam-role-to-an-existing-amazon-ec2-instance-by-using-the-aws-cli/ 

https://aws.amazon.com/blogs/security/easily-replace-or-attach-an-iam-role-to-an-existing-ec2-instance-by-using-the-ec2-console/ 

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-lifecycle.html 

Auto Scaling

Features

• Launch or terminate EC2 instances in an Auto Scaling group.
• Enable a DynamoDB table or a global secondary index to increase or decrease its provisioned read and write capacity to handle increases in traffic without throttling.
• Dynamically adjust the number of Aurora read replicas provisioned for an Aurora DB cluster to handle changes in active connections or workload.

Dynamic Vs Predictive Scaling

• Use Dynamic Scaling to add and remove capacity for resources to maintain resource utilization at the specified target value.
• Use Predictive Scaling to forecast your future load demands by analyzing your historical records for a metric. It also allows you to schedule scaling actions that proactively add and remove resource capacity to reflect the load forecast, and control maximum capacity behavior. Only available for EC2 Auto Scaling groups.

EC2 Auto Scaling

• Ensuring you have the correct number of EC2 instances available to handle your application load using Auto Scaling Groups.

• You specify the minimum, maximum and desired number of instances in each Auto Scaling group.
• Launch Configuration: Your group uses a launch configuration as a template for its EC2 instances. When you create a launch configuration, you can specify information such as the AMI ID, instance type, key pair, security groups, and block device mapping for your instances.
• Lifecycle: Pending, In-Service, Detached, Terminated
• You can add a lifecycle hook to your Auto Scaling group to perform custom actions when instances launch or terminate.
• The cooldown period is a configurable setting that helps ensure to not launch or terminate additional instances before previous scaling activities take effect.
• You can create launch templates that specifies instance configuration information when you launch EC2 instances, and allows you to have multiple versions of a template.
• A launch configuration is an instance configuration template that an Auto Scaling group uses to launch EC2 instances, and you specify information for the instances.
• CloudWatch Events – Auto Scaling can submit events to CloudWatch Events when your Auto Scaling groups launch or terminate instances, or when a lifecycle action occurs.
• SNS notifications – Auto Scaling can send Amazon SNS notifications when your Auto Scaling groups launch or terminate instances.
• Auto Scaling Group:  Launches instances based on config provided

• Can provision new when instance terminates. Check type: EC2
• Can provision new if ELB Health check fails. Check type: ELB
• Launch Configuration: Configuration of EC2 instances in auto scaling group

Instance Termination Policy

• If Multi A-Z, select AZ with most instances
• Find instance with oldest launch config
• If multiple instances have oldest, then pick one near billing hour
• If still, multiple then pick randomly

Exam Tips

Auto Scaling Lifecycle Hook, didn’t know before today’s exam, so please have a look by googling it.

The default termination policy is designed to help ensure that your network architecture spans Availability Zones evenly. With the default termination policy, the behavior of the Auto Scaling group is as follows:

1. If there are instances in multiple Availability Zones, choose the Availability Zone with the most instances and at least one instance that is not protected from scale in. If there is more than one Availability Zone with this number of instances, choose the Availability Zone with the instances that use the oldest launch configuration.

2. Determine which unprotected instances in the selected Availability Zone use the oldest launch configuration. If there is one such instance, terminate it.

3. If there are multiple instances to terminate based on the above criteria, determine which unprotected instances are closest to the next billing hour. (This helps you maximize the use of your EC2 instances and manage your Amazon EC2 usage costs.) If there is one such instance, terminate it.

4. If there is more than one unprotected instance closest to the next billing hour, choose one of these instances at random.

Amazon Autoscaling, please note that there are 4 Autoscaling plans namely, Main Current Instance Levels, Manual Scaling, Scheduled Scaling, and Dynamic Scaling. Remember if you want AS to launch different AMI’s than the one set up please remember you can’t modify Launch Configuration, which is the template for AS you must create new LC and then assign it to your AS, all the new instances will be launched with new AMI and all the previous one will still be running.

• Dedicated host = complete host, non virtualized for customer
• Dedicated instance = dedicated isolated instance running on hardware. More instances for same customer can run on this host.
• Use time based and load based scaling to have optimum and cost effective performance. There’s no price based or vendor based scaling.

References

https://tutorialsdojo.com/aws-cheat-sheet-aws-auto-scaling/ 

ELB

• Slow Start Mode gives targets time to warm up before the load balancer sends them a full share of requests.

Application Load Balancer

• Enable cross zone load balancing to start load balancing between cross zones
• Path patterns: Can route traffic based on path in URL
• Targets: EC2 instances or Auto Scaling group to load balance traffic to
• When you create a load balancer, you must specify one public subnet from at least two Availability Zones. You can specify only one public subnet per Availability Zone.
• Can do sticky sessions with load balancer generated cookies

Network Load Balancer

• Functions at the fourth layer of the Open Systems Interconnection (OSI) model. Uses TCP connections.
• At least 1 subnet must be specified when creating this type of load balancer, but the recommended number is 2.
• In the event that your Network load balancer is unresponsive, integration with Route 53 will remove the unavailable load balancer IP address from service and direct traffic to an alternate Network Load Balancer in another region.
• Can work with 1 public subnet but 2 recommended

Classic Load Balancer

• For use with EC2 classic only.
• Support for sticky sessions using application-generated cookies

Http Headers

• Application Load Balancers and Classic Load Balancers support X-Forwarded-For, X-Forwarded-Proto, and X-Forwarded-Port headers.

Exam Tips

• X-ForwardedFor has user’s ip address
• ELB Faq for classic load balancer is must and others. They come in exam a lot

• Disable sticky sessions if traffic is always going to one instance
• Reliability: It is what it is
• Durability: Stored
• Availability: Available when needed
• Resiliency: In case of failures, recovers
• AutoScaling, CloudWatch, EC2 Instances used for scalability. EFS is not required for it.
• Perfect Forward Secrecy is a feature that provides additional safeguards against the eavesdropping of encrypted data, through the use of a unique random session key. This prevents the decoding of captured data, even if the secret long-term key is compromised.
• CloudFront and Elastic Load Balancing are the two AWS services that support Perfect Forward Secrecy.
• You have to use an Application Load Balancer instead or a CloudFront web distribution to allow the SNI feature.
• Amazon EC2 Auto Scaling supports the following types of scaling policies:
• Target tracking scaling - Increase or decrease the current capacity of the group based on a target value for a specific metric. This is similar to the way that your thermostat maintains the temperature of your home – you select a temperature and the thermostat does the rest.
• Step scaling - Increase or decrease the current capacity of the group based on a set of scaling adjustments, known as step adjustments, that vary based on the size of the alarm breach.
• Simple scaling - Increase or decrease the current capacity of the group based on a single scaling adjustment.

Load Balancers in a VPC

• To ensure that your load balancer can scale properly, verify that each subnet for your load balancer has a CIDR block with at least a /27 bitmask (for example,10.0.0.0/27) and has at least 8 free IP addresses. Your load balancer uses these IP addresses to establish connections with the instances.
• ClassicLink enables your EC2-Classic instances to communicate with VPC instances using private IP addresses, provided that the VPC security groups allow it. If you plan to register linked EC2-Classic instances with your load balancer, you must enable ClassicLink for your VPC, and then create your load balancer in the ClassicLink-enabled VPC.

References

https://acloud.guru/learn/aws-application-loadbalancer 

https://tutorialsdojo.com/aws-cheat-sheet-aws-elastic-load-balancing-elb/ https://tutorialsdojo.com/aws-cheat-sheet-ec2-instance-health-check-vs-elb-health-check-vs-auto-scaling-and-custom-health-check-2/

https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-backend-instances.html 

ECS

• When using the EC2 launch type, then your clusters are a group of container instances you manage. These clusters can contain multiple different container instance types, but each container instance may only be part of one cluster at a time.

Components

Containers and Images: Your application components must be architected to run in containers. Containers are created from a read-only template called an image.

Task Components

• Task definitions specify various parameters for your application. It is a text file, in JSON format, that describes one or more containers, up to a maximum of ten, that form your application

Fargate

AWS Fargate is a compute engine for Amazon ECS that allows you to run containers without having to manage servers or clusters.

Amazon ECS has two modes: Fargate launch type and EC2 launch type. With Fargate launch type, all you have to do is package your application in containers, specify the CPU and memory requirements, define networking and IAM policies, and launch the application. EC2 launch type allows you to have server-level, more granular control over the infrastructure that runs your

container applications.

• Fargate only supports container images hosted on Elastic Container Registry (ECR) or Docker Hub.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-elastic-container-service-amazon-ecs/

AWS Systems Manager

Overview

• Create logical groups of resources such as applications, different layers of an application stack, or production versus development environments.

• You can select a resource group and view its recent API activity, resource configuration changes, related notifications, operational alerts, software inventory, and patch compliance status.

• Provides a browser-based interactive shell and CLI for managing Windows and Linux EC2 instances, without the need to open inbound ports, manage SSH keys, or use bastion hosts.
• SSM Agent is the tool that processes Systems Manager requests and configures your machine as specified in the request. SSM Agent must be installed on each instance you want to use with Systems Manager. On some instance types, SSM Agent is installed by default. On others, you must install it manually.

Systems Manager provides predefined automation documents for common operational tasks, such as stopping and restarting an EC2 instance, that you can customize to your own specific use cases. Systems Manager also has built-in safety controls, allowing you to incrementally roll out new changes and automatically halt the roll-out when errors occur.

With Systems Manager, you can view detailed system configurations, operating system patch levels, software installations, application configurations, and other details about your environment through the Systems Manager dashboard.

With AWS Systems Manager, you can manage servers running on AWS and in your on-premises data center through a single interface. Systems Manager securely communicates with a lightweight agent installed on your servers to execute management tasks.

Exam Tips

Amazon ECS enables you to inject sensitive data into your containers by storing your sensitive data in either AWS Secrets Manager secrets or AWS Systems Manager Parameter Store parameters and then referencing them in your container definition. This feature is supported by tasks using both the EC2 and Fargate launch types.

References

https://tutorialsdojo.com/aws-cheat-sheet-aws-systems-manager/ 

Well Architected Framework whitepaper - Operational Excellence

Databases

https://aws.amazon.com/products/databases/ 

RDS

• RDS is all OLTP and comes in six different DBs. Postgres, MySql, Mariadb, MSSQL, Oracle, Aurora
• You can get high availability with a primary instance and a synchronous secondary instance that you can fail over to when problems occur.
• Provisioned storage limits restrict the maximum size of a MySQL table file to 16 TB.
• The Point-In-Time Restore and snapshot restore features of Amazon RDS for MySQL require a crash-recoverable storage engine and are supported for the InnoDB storage engine only.
• InnoDB is the recommended and supported storage engine for MySQL DB instances on Amazon RDS.
• You can now create Amazon RDS for Oracle database instances with up to 64 TiB of storage (32 TiB originally) and provisioned I/O performance of up to 80,000 IOPS.
• Max SQL Server: 16 TB
• You can’t stop an Amazon RDS for SQL Server DB instance in a Multi-AZ configuration.
• MySQL and PostgreSQL both support IAM database authentication.

• Restored RDS has new endpoint url so you need to change that
• Take note that there are certain differences between CloudWatch and Enhanced Monitoring Metrics.  CloudWatch gathers metrics about CPU utilization from the hypervisor for a DB instance, and Enhanced Monitoring gathers its metrics from an agent on the instance. As a result, you might find differences between the measurements, because the hypervisor layer performs a small amount of work.
• Enhanced Monitoring metrics are useful when you want to see how different processes or threads on a DB instance use the CPU.
• When zone is gone, it fails over automatically and updates dns it’s not for performance.

• For performance, we need read replicas

• can force failover by rebooting rds instance
• CloudWatch gathers metrics about CPU utilization from the hypervisor for a DB instance, and Enhanced Monitoring gathers its metrics from an agent on the instance.
• RDS Performance Insights monitors your DB instance load so that you can analyze and troubleshoot your database performance. You can visualize the database load and filter the load by waits, SQL statements, hosts, or users.
• DB Security groups are used in Classic EC2. VPN security groups are used in RDS.
• By default, customers are allowed to have up to a total of 40 Amazon RDS DB instances. Of those 40, up to 10 can be Oracle or SQL Server DB instances under the “License Included” model. All 40 can be used for Amazon Aurora, MySQL, MariaDB, PostgreSQL and Oracle under the “BYOL” model.
• Amazon RDS reserved instances are purchased for a Region rather than for a specific Availability Zone.
• You can use AWS Config to continuously record configurations changes to Amazon RDS DB Instances, DB Subnet Groups, DB Snapshots, DB Security Groups, and Event Subscriptions and receive notification of changes through Amazon Simple Notification Service (SNS).

Backups

• By default, Amazon RDS enables automated backups of your DB Instance with a 7 day retention period. Free backup storage is limited to the size of your provisioned database and only applies to active DB Instances.
• There is no I/O suspension for Multi-AZ DB deployments, since the backup is taken from the standby.

VPC

• A DB Subnet Group is a collection of subnets that you may want to designate for your RDS DB Instances in a VPC. Each DB Subnet Group should have at least one subnet for every Availability Zone in a given Region. When creating a DB Instance in VPC, you will need to select a DB Subnet Group.

Automatic Backups

• The automated backup feature of Amazon RDS enables point-in-time recovery of your DB instance. When automated backups are turned on for your DB Instance, Amazon RDS automatically performs a full daily snapshot of your data (during your preferred backup window) and captures transaction logs (as updates to your DB Instance are made).

• Amazon RDS retains backups of a DB Instance for a limited, user-specified period of time called the retention period, which by default is 7 days but can be set to up to 35 days. You can initiate a point-in-time restore and specify any second during your retention period, up to the Latest Restorable Time.

DB Snapshots

• DB Snapshots are user-initiated and enable you to back up your DB instance in a known state as frequently as you wish, and then restore to that specific state at any time.

Encryption

• At rest and in-transit.
• Manage keys used for encrypted DB instances using the AWS KMS. KMS encryption keys are specific to the region that they are created in.
• You can’t have an encrypted Read Replica of an unencrypted DB instance or an unencrypted Read Replica of an encrypted DB instance.
• You can’t restore an unencrypted backup or snapshot to an encrypted DB instance.
• Amazon RDS supports encryption at rest for all database engines, using keys you manage using AWS Key Management Service (KMS). On a database instance running with Amazon RDS encryption, data stored at rest in the underlying storage is encrypted, as are its automated backups, read replicas, and snapshots.

Enhanced Metrics

CloudWatch gathers metrics about CPU utilization from the hypervisor for a DB instance, and Enhanced Monitoring gathers its metrics from an agent on the instance.

In RDS, the Enhanced Monitoring metrics shown in the Process List view are organized as follows:

-RDS child processes – Shows a summary of the RDS processes that support the DB instance

-RDS processes – Shows a summary of the resources used by the RDS management agent, diagnostics monitoring processes, and other AWS processes that are required to support RDS DB instances.

-OS processes – Shows a summary of the kernel and system processes, which generally have minimal impact on performance.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-relational-database-service-amazon-rds/ 

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Overview.DBInstance.Modifying.html 

https://aws.amazon.com/rds/faqs/#reserved-instances 

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Overview.RDSSecurityGroups.html

RDS Cloud Guru Course: https://acloud.guru/learn/aws-rds 

Aurora

• Starts with 10GB and scales upto 64 TB in 10 GB increments
• Can scale upto 32 CPU and 244 GB RAM
• 2 copies of data in each AZ min 3 AZ. So 6 copies of data. Only available with 3 AZ regions.
• Super high availability.
• Low latency replication.
• Backups don’t impact db performance
• Snapshots also don’t impact db performance
• To migrate mysql to aurora, create read replica then promote it
• compatible with both postgres and mysql
• Aurora Serverless is Serverless
• Amazon Aurora is up to five times faster than standard MySQL databases and three times faster than standard PostgreSQL databases. Amazon Aurora features a distributed, fault-tolerant, self-healing storage system that auto-scales up to 64TB per database instance. It delivers high performance and availability with up to 15 low-latency read replicas, point-in-time recovery, continuous backup to Amazon S3, and replication across three Availability Zones (AZs).
• Amazon Aurora Multi-Master is a new feature of the Aurora MySQL-compatible edition that adds the ability to scale out write performance across multiple Availability Zones, allowing applications to direct read/write workloads to multiple instances in a database cluster and operate with higher availability.
• Amazon Aurora Serverless is an on-demand, autoscaling configuration for the MySQL-compatible and PostgreSQL-compatible editions of Amazon Aurora. An Aurora Serverless DB cluster automatically starts up, shuts down, and scales capacity up or down based on your application’s needs. Aurora Serverless provides a relatively simple, cost-effective option for infrequent, intermittent, or unpredictable workloads.
• Cluster endpoint – connects to the current primary DB instance for a DB cluster. This endpoint is the only one that can perform write operations.
• Reader endpoint – connects to one of the available Aurora Replicas for that DB cluster. Each Aurora DB cluster has one reader endpoint. The reader endpoint provides load-balancing support for read-only connections to the DB cluster. Use the reader endpoint for read operations, such as queries. You can’t use the reader endpoint for write operations.
• Custom endpoint – represents a set of DB instances that you choose. When you connect to the endpoint, Aurora performs load balancing and chooses one of the instances in the group to handle the connection.
• Instance endpoint – connects to a specific DB instance within an Aurora cluster.
• Aurora MySQL parallel query is an optimization that parallizes some of the I/O and computation involved in processing data-intensive queries.

References

https://tutorialsdojo.com/amazon-aurora/ 

https://aws.amazon.com/rds/aurora/faqs/ 

DynamoDB

• NoSQL
• Stored on SSD
• Spread across 3 regions
• eventually consistent (within 1 second)
• Can do strongly consistent
• Provides on-demand backup capability as well as enable point-in-time recovery for your DynamoDB tables. With point-in-time recovery, you can restore that table to any point in time during the last 35 days.
• You can create tables that are automatically replicated across two or more AWS Regions, with full support for multi-master writes.
• Primary Key – uniquely identifies each item in the table, so that no two items can have the same key. Must be scalar.

• Partition key – a simple primary key, composed of one attribute.
• Partition key and sort key (composite primary key) – composed of two attributes.
• DynamoDB uses the partition key value as input to an internal hash function. The output from the hash function determines the partition in which the item will be stored. All items with the same partition key are stored together, in sorted order by sort key value. If no sort key is used, no two items can have the same partition key value.

• DynamoDB Streams – an optional feature that captures data modification events in DynamoDB tables.
• Stream records have a lifetime of 24 hours; after that, they are automatically removed from the stream.
• You can use DynamoDB Streams together with AWS Lambda to create a trigger, which is a code that executes automatically whenever an event of interest appears in a stream.
• Throttling prevents your application from consuming too many capacity units. DynamoDB can throttle read or write requests that exceed the throughput settings for a table, and can also throttle read requests exceeds for an index.
• When a request is throttled, it fails with an HTTP 400 code (Bad Request) and a ProvisionedThroughputExceededException.
• You create a scaling policy for a table or a global secondary index. The scaling policy specifies whether you want to scale read capacity or write capacity (or both), and the minimum and maximum provisioned capacity unit settings for the table or index. The scaling policy also contains a target utilization, which is the percentage of consumed provisioned throughput at a point in time.
• You can use the UpdateItem operation to implement an atomic counter – a numeric attribute that is incremented, unconditionally, without interfering with other write requests.
• DynamoDB optionally supports conditional writes for these operations: PutItem, UpdateItem, DeleteItem. A conditional write will succeed only if the item attributes meet one or more expected conditions.
• Conditional writes can be idempotent if the conditional check is on the same attribute that is being updated. DynamoDB performs a given write request only if certain attribute values in the item match what you expect them to be at the time of the request.
• Encrypts your data at rest using an AWS Key Management Service (AWS KMS) managed encryption key for DynamoDB.
• Encryption at rest can be enabled only when you are creating a new DynamoDB table.
• DynamoDB Accelerator (DAX) delivers microsecond response times for accessing eventually consistent data.
• An item collection is all the items in a table and its local secondary indexes that have the same partition key. No item collection can exceed 10 GB, so it’s possible to run out of space for a particular partition key value.

Best Practices

• Provisioned capacity can be increased as long as one partition key doesn’t exceed 3000 RCUs or 1000 WCUs.
• Burst capacity is capacity reserved for 5 minutes when you’re not using your full capacity.
• Partition keys should be distinct. More keys you access while retrieving data, more distributed your load will be.
• Sharding Using Random Suffixes: One strategy for distributing loads more evenly across a partition key space is to add a random number to the end of the partition key values. Then you randomize the writes across the larger space.
• Sharding Using Calculated Suffixes: A randomizing strategy can greatly improve write throughput. But it’s difficult to read a specific item because you don’t know which suffix value was used when writing the item. To make it easier to read individual items, you can use a different strategy. Instead of using a random number to distribute the items among partitions, use a number that you can calculate based upon something that you want to query on.
• Composite keys should represent one to many relationships.
• In Secondary indexes,  Avoid projecting attributes that you know will rarely be needed in queries. Every time you update an attribute that is projected in an index, you incur the extra cost of updating the index as well. You can still retrieve non-projected attributes in a Query at a higher provisioned throughput cost, but the query cost may be significantly lower than the cost of updating the index frequently
•  Consider projecting fewer attributes to minimize the size of items written to the index. However, this only applies if the size of projected attributes would otherwise be larger than a single write capacity unit (1 KB). For example, if the size of an index entry is only 200 bytes, DynamoDB rounds this up to 1 KB. In other words, as long as the index items are small, you can project more attributes at no extra cost.
• Adjacency List Pattern is dope
• Overload global secondary indexes for more swag (See best practices documentation. It’s awesome.)

Scan and Query Operation Optimization

• Scan operations read full items and have to read all items. A scan can consume upto 1MB or 1 data page so 1MB / 4KB / 2 = 128 RCU. A strongly consistent scan will consume 256 RCUs. It can cause throttling to partition.

Reduce page size

Because a Scan operation reads an entire page (by default, 1 MB), you can reduce the impact of the scan operation by setting a smaller page size. The Scan operation provides a Limit parameter that you can use to set the page size for your request. Each Query or Scan request that has a smaller page size uses fewer read operations and creates a “pause” between each request. For example, suppose that each item is 4 KB and you set the page size to 40 items. A Query request would then consume only 20 eventually consistent read operations or 40 strongly consistent read operations. A larger number of smaller Query or Scan operations would allow your other critical requests to succeed without throttling.

Isolate scan operations

DynamoDB is designed for easy scalability. As a result, an application can create tables for distinct purposes, possibly even duplicating content across several tables. You want to perform scans on a table that is not taking “mission-critical” traffic. Some applications handle this load by rotating traffic hourly between two tables—one for critical traffic, and one for bookkeeping. Other applications can do this by performing every write on two tables: a “mission-critical” table, and a “shadow” table.

A parallel scan can be the right choice if the following conditions are met:

• The table size is 20 GB or larger.

• The table’s provisioned read throughput is not being fully used.

• Sequential Scan operations are too slow.

Secondary Indexes

Global secondary index—An index with a partition key and a sort key that can be different from those on the base table. A global secondary index is considered “global” because queries on the index can span all of the data in the base table, across all partitions. A global secondary index has no size limitations and has its own provisioned throughput settings for read and write activity that are separate from those of the table.

Local secondary index—An index that has the same partition key as the base table, but a different sort key. A local secondary index is “local” in the sense that every partition of a local secondary index is scoped to a base table partition that has the same partition key value. As a result, the total size of indexed items for any one partition key value can’t exceed 10 GB. Also, a local secondary index shares provisioned throughput settings for read and write activity with the table it is indexing.

Each table in DynamoDB is limited to 20 global secondary indexes (default limit) and 5 local secondary indexes.

Exam Tips

• If you enable DynamoDB Streams on a table, you can associate the stream ARN with a Lambda function that you write. Immediately after an item in the table is modified, a new record appears in the table’s stream. AWS Lambda polls the stream and invokes your Lambda function synchronously when it detects new stream records. The Lambda function can perform any actions you specify, such as sending a notification or initiating a workflow.
• Indexes are sparse and only contain items from table which applies to index. They can be useful to limit the size and cost of reads. Regardless of what attributes are read, read costs are for the full item.
• Each read is 4 KB, Writes are 1 KB. One RCU = 2 reads per second. Once RCU = 8 kbs data read per second. Eventual consistency reads are half the cost.
• DynamoDB allows for the storage of large text and binary objects, but there is a limit of 400 KB.
• Headers sent to DynamoDB API:

• X-Amz-Target
• X-Amz-Date
• Host
• Authorization

• Headers received in response:

• x-Amz-RequestID
• x-amz-crc32

Limits

• One read capacity unit = one strongly consistent read per second, or two eventually consistent reads per second, for items up to 4 KB in size.
• One write capacity unit = one write per second, for items up to 1 KB in size.
• Transactional read requests require two read capacity units to perform one read per second for items up to 4 KB.
• Transactional write requests require two write capacity units to perform one write per second for items up to 1 KB.
• 20 Global Secondary Indexes
• 40000 max RCUs and WCUs per table
• 80000 RCUs/WCUs per account
• Total number of non key attributes must not exceed
  1. Same attribute in GSI is counted twice.
• For every distinct partition key value, the total sizes of all table and index items cannot exceed 10 GB.
• A transaction cannot contain more than 25 unique items.
• A transaction cannot contain more than 4 MB of data.

Encryption

 AWS owned CMK – Default encryption type. The key is owned by DynamoDB (no additional charge).

 AWS managed CMK – The key is stored in your account and is managed by AWS KMS (AWS KMS charges apply).

Pricing

Provisioned throughput (write):

One write capacity unit (WCU) provides up to one write per second of upto 1 KB data or 2 WCUs for 1 KB transactional write, enough for 2.5 million writes per month. As low as $0.47 per month per WCU.

Provisioned throughput (read)

One read capacity unit (RCU) provides up to two reads per second with eventual consistency and one read per second for strongly consistent read, enough for 5.2 million reads per month. As low as $0.09 per RCU.

Indexed data storage

DynamoDB charges an hourly rate per GB of disk space

that your table consumes. As low as $0.25 per GB.

References

https://acloud.guru/learn/aws-dynamodb 

https://tutorialsdojo.com/aws-cheat-sheet-amazon-dynamodb/

https://aws.amazon.com/dynamodb/faqs/ 

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html 

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html 

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/CapacityUnitCalculations.html 

See https://www.youtube.com/watch?v=HaEPXoXVf2k 

And https://www.youtube.com/watch?v=jzeKPKpucS0 

Redshift

• 1000$ per TB per year
• Single Node 160 GB or Multi node
• Leader node handles client connections and queries and compute nodes handle work. Can have upto 128 compute nodes.
• Backups are default to 1 day retention period
• maintains at least three copies. One your master then replica on compute nodes and then on S3
• Can snapshot data to s3 async
• Charged per compute node hour
• Only available in one AZ at a time
• Max backup retention is 35 days
• Redshift spectrum can be used to query exabytes of data in S3.
• Node Type

• Dense storage (DS) node type – for large data workloads and use hard disk drive (HDD) storage.
• Dense compute (DC) node types – optimized for performance-intensive workloads. Uses SSD storage.

Exam Tips

• No Auto Scaling. Nodes can be added as read only while cluster remains in service.

References

Check out this Amazon Redshift Cheat Sheet:

https://tutorialsdojo.com/aws-cheat-sheet-amazon-redshift/

Redshift Course on A Cloud Guru:

https://acloud.guru/learn/aws-redshift-table-design

https://aws.amazon.com/redshift/faqs/ 

Elasticache

• Memsql scales horizontally and has multi threaded performance. It doesn’t support Multi AZ
• Redis doesn’t scale horizontally but has a lot of features.
• Can do backup and restores of Redis but not of memsql
• Cache is used to increase db/web performance.
• Can be placed between RDS and Application to cache queries

• Can have upto 15 replicas
• Can failover automatically to read replica

ElastiCache Redis

• Automatic detection and recovery from cache node failures.
• Multi-AZ with automatic failover of a failed primary cluster to a read replica in Redis clusters that support replication.
• Redis (cluster mode enabled) supports partitioning your data across up to 90 shards.
• Redis supports in-transit and at-rest encryption with authentication so you can build HIPAA-compliant applications.
• Flexible Availability Zone placement of nodes and clusters for increased fault tolerance.
• Data is persistent.
• Auth by providing redis auth header

Memcached

• Automatic discovery of nodes within a cluster enabled for automatic discovery, so that no changes need to be made to your application when you add or remove nodes.
• Flexible Availability Zone placement of nodes and clusters.
• ElastiCache Auto Discovery feature for Memcached lets your applications identify all of the nodes in a cache cluster and connect to them.
• ElastiCache node access is restricted to applications running on whitelisted EC2 instances. You can control the instances that can access your cluster by using subnet groups or security groups.
• It is not persistent.
• Supports large nodes with multiple cores or threads.
• Does not support multi-AZ failover or replication

Caching Strategies

Lazy Loading – a caching strategy that loads data into the cache only when necessary.

Write Through – adds data or updates data in the cache whenever data is written to the database.

• Data in the cache is never stale.

By adding a time to live (TTL) value to each write, we are able to enjoy the advantages of each strategy and largely avoid cluttering up the cache with superfluous data.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-elasticache/

Athena

Amazon Athena is an interactive query service that

makes it easy for you to analyze data in Amazon S3 using standard SQL. Athena is

serverless, so there is no infrastructure to manage, and you pay only for the queries

that you run.

See https://aws.amazon.com/athena/faqs/ 

Elastic Search

• Amazon ES lets you search, analyze, and visualize your data in real-time. This service manages the capacity, scaling, patching, and administration of your Elasticsearch clusters for you, while still giving you direct access to the Elasticsearch APIs.
• The service offers open-source Elasticsearch APIs, managed Kibana, and integrations with Logstash and other AWS Services. This combination is often coined as the ELK Stack.
• An Amazon ES domain is synonymous with an Elasticsearch cluster. Domains are clusters with the settings, instance types, instance counts, and storage resources that you specify.
• Kibana, an open-source analytics and visualization platform. Kibana is automatically deployed with your Amazon Elasticsearch Service domain.
• You can load streaming data from the following sources using AWS Lambda event handlers:

• Amazon S3
• Amazon Kinesis Data Streams and Data Firehose
• Amazon DynamoDB
• Amazon CloudWatch
• AWS IoT

• Amazon ES uses Amazon Cognito to offer username and password protection for Kibana. (Optional feature)

• You can deploy your Amazon ES instances across multiple AZs (up to three).

• Even if you select two Availability Zones when configuring your domain, Amazon ES automatically distributes dedicated master nodes across three Availability Zones. This distribution helps prevent cluster downtime if a zone experiences a service disruption. It also assists in electing a new master node through a quorum between the two remaining nodes.
• Use Cases

• Log Analytics
• Real-Time Application Monitoring
• Security Analytics
• Full Text Search
• Clickstream Analytics

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-elasticsearch-amazon-es/

Route 53

Alias Records

• You can create special Route 53 records, called alias records, that route traffic to S3 buckets, CloudFront distributions, and other AWS resources.
• Queries to Alias records are provided at no additional cost to current Route 53 customers when the records are mapped to the following AWS resource types:

• Elastic Load Balancers
• Amazon CloudFront distributions
• AWS Elastic Beanstalk environments
• Amazon S3 buckets that are configured as website endpoints
• Alias with type A possible for domains. Alias with type AAAA for ipv6. No Alias with type CNAME.

Exam tips

• ELB doesn’t have ipv4 address. We always need a DNS record to resolve to it. More about it in ELB section.
• Alias Record vs CNAME: Can’t have cname for naked domain name like acloud.guru. CNAME must be some subdomain.
• When given the choice between Alias Record vs CNAME always choose Alias Record.
• When creating a record in Route 53 to other AWS resources, including ALB’s, you should use Alias records where available.
• Route 53 has a security feature that prevents internal DNS from being read by external sources. The work around is to create a EC2 hosted DNS instance that does zone transfers from the internal DNS, and allows itself to be queried by external servers.

DNS record types

• SOA => TTL, zone, administrator of zone, current version of data file
• NS => which name server is primary
• A Record => A record resolves to ip
• CNAME => Alias to other domain
• MX Records => mail
• PTR Records => Reverse of A record, resolves name of ip

Simple Routing Policy

• One record with multiple ip address
• All IP addresses are returned in random order to user

Weighted Routing Policy

• Split traffic based on weight
• 10% to EAST 1 and 90% to WEST
• Health checks can help eliminate unhealthy instances. Can also setup SNS notifications

Latency Based Routing

• Routes based on how much latency will user face when connecting to a server. So if user is in London, he will get Irish web server.

Failover Policy

• It fails over to passive server depending on health check

Geolocation Routing Policy

• Routes to specific ips depending on where the user is coming from. A default must be set otherwise all requests with no geolocation record set will fail.

Geo proximity Routing

• Can route traffic based on the locations of your users as well as resources. You must use Route 53 Traffic Flow for this. Not tested in exam.

Multivalue Answer Policy

• Same as Simple Routing policy but you can put health checks so only healthy ips will be given to the client.

Keep in mind AWS use ALIAS record for zone apex (naked domain) not CNAME.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-route-53/ 

https://aws.amazon.com/route53/faqs/ 

VPC

The first four IP addresses and the last IP address in each subnet CIDR block are not available for you to use, and cannot be assigned to an instance.

Route table, ACL, and Network Security group when you create new VPC

No subnet or internet gateway

one subnet = one AZ

Availability zones are randomized

One internet gateway per VPC. Can’t attach multiple

Security groups are specific to VPC

Amazon reserves 5 ip addresses in your subnet

If there is more than one rule for a specific port, we apply the most permissive rule. For example, if you have a rule that allows access to TCP port 22 (SSH) from IP address 203.0.113.1 and another rule that allows access to TCP port 22 from everyone, everyone has access to TCP port 22.

• AWS PrivateLink enables you to privately connect your VPC to supported AWS services, services hosted by other AWS accounts (VPC endpoint services), and supported AWS Marketplace partner services. You do not require an internet gateway, NAT device, public IP address, AWS Direct Connect connection, or VPN connection to communicate with the service. Traffic between your VPC and the service does not leave the Amazon network.
• You can create a VPC peering connection between your VPCs, or with a VPC in another AWS account, and enable routing of traffic between the VPCs using private IP addresses. You cannot create a VPC peering connection between VPCs that have overlapping CIDR blocks.

NAT instance vs NAT Gateway

NAT instance is single instance and Gateway is multiple highly available instances

Must disable src and dst ip check for nat instance

NAT instance is behind a security group

Must be route out of private subnet to nat instance to allow traffic

If bottleneck, increase instance size

Instance Gateways

Gateway is managed by amazon

Redundant among an AZ. Can be made multi AZ

Starts at 5 GBps and can scale upto 45 GBPs

Not associate with security group

Network ACLS

New network ACL denies everything

Deny must be before allow for a ip range

One subnet has one ACL but one ACL can be associated with many subnets

Network ACLs are first and then security groups come

Default ACL comes with VPC and it allows all
If you dont associate an ACL to subnet, it goes to default ACL

Network ACLs run lowest number rule first and return when first rule matches

Stateless, so need to do it for both inbound and outbound.

Load Balancers and Custom VPC

We need at least two public facing subnets to create a load balancer.

Flow logs

Can’t enable flow logs for VPN which is peered to your VPC unless peered VPC is in your account

Can’t tag a flow log.

Once flow log is created, you can’t modify its configuration

Amazon DNS traffic is not monitored

Traffic to 169.254.169.254 is not monitored

DHCP is not monitored

Traffic to default VPC router is not monitored

Flow logs on VPC, subnet and network interface level

Bastion Host

Bastions are used to administer EC2 instances and are the only way to get in the cluster. They are created to reduce surface area of attack. Can’t use NAT gateway as bastion

Direct Connect

Directly connects your data center to aws

Useful for high throughput

If you need stable and reliable connection

For VPN question dropping, use Direct Connect

VPC Endpoints

Allow you to connect to Amazon Services without needing NAT or Internet gateway.

Two types:

Interface Endpoints

Elastic Network Interface with private IP which can be used to reach other amazon services

VPC endpoints are enabled by PrivateLink

5vpc per region

Routes/Internet Gateway must be before launching instance

NAT instance must be in public subnet and route of private subnet has a rule saying 0.0.0.0/0 will go through NAT gateway

Interface endpoints

Attach ENI with private IP to instance

Gateway Endpoints

They’re supported for dynamodb and S3 currently

To ensure that only you can bring your address range to your AWS account, you must authorize Amazon to advertise the address range and provide proof that you own the address range.

A Route Origin Authorization (ROA) is a document that you can create through your Regional internet registry (RIR), such as the American Registry for Internet Numbers (ARIN) or Réseaux IP Européens Network Coordination Centre (RIPE). It contains the address range, the ASNs that are allowed to advertise the address range, and an expiration date.

ENI

An elastic network interface (ENI) is a logical networking component in a VPC that represents a virtual network card. You can attach a network interface to an EC2 instance in the following ways:

1. When it’s running (hot attach)
2. When it’s stopped (warm attach)
3. When the instance is being launched (cold attach).

Exam Tips

• Please know if an instance is configured properly on custom VPC with Internet Gateway routing the traffic to internet in public subnet and Security Group and Network ACLs defining right ports for connection and still not able to connect to your instance consider assigning Public IP/Elastic IP.
• Please know how Virtual Private Network (VPN) connection works and Direct Gateway for private connections, don’t mix with PRIVATE SUBNET, you can use public subnet with VPN.
• While if you using a NAT instance and you have configured it all correct but when connecting your private subnet instance to internet for outbound traffic it’s connecting, but WHY? You forgot to Disable Source/Destination checks flag, exactly this was question on my exam. Wait do you know what we can use other than NAT instance and NAT gateway to give secure outbound internet connect to our private subnet, that’s bastion host or call it jump server, and it resides in public subnet, got 2 questions on this single point with different scenarios.
• AWS provides instances launched in a non-default VPC with private DNS hostname and possibly a public DNS hostname, depending on the DNS attributes you specify for the VPC and if your instance has a public IPv4 address.
• Set VPC attributes enableDnsHostnames and enableDnsSupport to true so that your instances receive a public DNS hostname and Amazon-provided DNS server can resolve Amazon-provided private DNS hostnames.

• If you use custom DNS domain names defined in a private hosted zone in Route 53, the enableDnsHostnames and enableDnsSupport attributes must be set to true.

• Max 5 VPC per region
• 200 Subnets per VPC
• Once a VPC is set to Dedicated hosting, it can be changed back to default hosting via the CLI, SDK or API. Note that this will not change hosting settings for existing instances, only future ones. Existing instances can be changed via CLI, SDK or API but need to be in a stopped state to do so. Note dedicated VPC != Dedicated EC2 tenancy
• NAT instances are for internet. They have nothing to do with VPN.
• Direct Connect is carrier, but VPN still needs to be configured. Assign ASN for VPN.

VPC Endpoints

• Privately connect your VPC to supported AWS services and VPC endpoint services powered by PrivateLink without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect connection.
• Endpoints are virtual devices.

Interface Endpoints: An elastic network interface with a private IP address that serves as an entry point for traffic destined to a supported service.

Gateway Endpoints: A gateway that is a target for a specified route in your route table, used for traffic destined to a supported AWS service.

• You can create multiple endpoints in a single VPC, for example, to multiple services. You can also create multiple endpoints for a single service, and use different route tables to enforce different access policies from different subnets to the same service.

• Endpoints support IPv4 traffic only.

• ClassicLink: Allows you to link an EC2-Classic instance to a VPC in your account, within the same region. This allows you to associate the VPC security groups with the EC2-Classic instance, enabling communication between your EC2-Classic instance and instances in your VPC using private IPv4 addresses.

Remember that for S3 and DynamoDB service, you have to use a Gateway VPC Endpoint and not an Interface VPC Endpoint.

References

FAQ https://aws.amazon.com/vpc/faqs/ 

https://tutorialsdojo.com/aws-cheat-sheet-amazon-vpc/

 

https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Subnets.html 

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstancesConnecting.html 

https://aws.amazon.com/blogs/security/securely-connect-to-linux-instances-running-in-a-private-amazon-vpc/ 

https://docs.aws.amazon.com/vpc/latest/userguide/VPC_NAT_Instance.html 

https://docs.aws.amazon.com/vpc/latest/userguide/vpc-network-acls.html#nacl-ephemeral-ports 

https://docs.aws.amazon.com/vpn/latest/s2svpn/VPC_VPN.html 

https://docs.aws.amazon.com/directconnect/latest/UserGuide/direct-connect-gateways.html 

https://docs.aws.amazon.com/directconnect/latest/UserGuide/Colocation.html 

VPC labs: https://learn.acloud.guru/labs/search?service=VPC 

SQS

• Is a queue. It can store upto 256KB of text. Can scale upto 2 GB but data is stored in S3 Standard and FIFO queues

• Standard queues guarantee delivery but may deliver more than once occasionally. They give almost unlimited transactions per second

• FIFO queues are strictly ordered and always deliver once
• Can store messages from 1 minute to 14 days. Default retention period is 4 day.
• Visibility timeout is time a message is invisible in queue after reader picks it up. Provided a reader completes task and acknowledges, messages is then deleted. If readers doesn’t acknowledge in time, then messages reappears and is delivered to a reader which can result in duplicate message delivery.
• Visibility timeout is max 12 hours
• Long poll doesn’t return until a message arrives or long poll timeouts
• SQS is pull based.
• Note message must be deleted before visibility timeout
• Amazon MQ can serve multiple subscribers at once. SQS can’t.

• You can include structured metadata (such as timestamps, geospatial data, signatures, and identifiers) with messages using message attributes.
• Message timers let you specify an initial invisibility period for a message added to a queue. The default (minimum) invisibility period for a message is 0 seconds. The maximum is 15 minutes.
• You can configure an existing SQS queue to trigger an AWS Lambda function when new messages arrive in a queue.
• You can delete all the messages in your queue by purging them.
• SQS supports dead-letter queues, which other queues can target for messages that can’t be processed successfully.
• Delay queues let you postpone the delivery of new messages to a queue for a number of seconds.
• Send, receive, or delete messages in batches of up to 10 messages or 256KB.

Limits

• 256 kb batch limit
• 10 messages batch limit
• One request = 64 KB
• Charges per million requests
• Default delay for queue is 0 minutes, Max is 15.
• Fifo queues name must end with .fifo
• Queue names can’t be more than 80 chars
• Max 10 attributes per message
• Standard queue has unlimited TPS
• FIFO supports 3000 messages per second with batch or 300 without batch
• Visibility timeout max is 12 hours
• Longpoll max timeout is 20 seconds

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-sqs/

https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-how-it-works.html 

SWF

SWF is workflow service. You can have flows consisting of code => service calls => humans => scripts. SWF is used by Amazon in Order processing

SWF flows can last upto 1 year

SWF Actors

• WOrkflow starters => Application that can start a workflow
• Deciders => Control flow. Decides what to do when a workflow is finished or failed
• Activity Workers => Do the actual work

SNS

Can push notifications to SQS, Mobile Devices. Can send SMS or emails. Or call any HTTP endpoint

A SNS topic is way to organize multiple recipients. Topic can be subscribed to by recipients

SNS is push based

SNS vs SQS

SNS is push based SQS is pull based

Can filter subscription based on message attribute

Direct addressing allows you to deliver notifications directly to a single endpoint, rather than sending identical messages to all subscribers of a topic. This is useful if you want to deliver precisely targeted messages to each recipient.

SMS messages that are of high priority to your business should be marked as Transactional. This ensures that messages such as those that contain one-time passwords or PINs get delivered over routes with the highest delivery reliability.

SMS messages that carry marketing messaging should be marked Promotional. Amazon SNS ensures that such messages are sent over routes that have a reasonable delivery reliability but are substantially cheaper than the most reliable routes.

Limits

• A single SMS message can contain a maximum of 140 bytes of information.
• With the exception of SMS messages, SNS messages can contain up to 256 KB of text data.

Elastic Transcoder

It converts your media files to other format. Images not supported. Only audio + Video

KINESIS

Streaming data. Stock Market, Games, Social Network data, Geospatial data like Uber, iOT sensor data.

Kinesis is a place to send your streaming data to in AWS.

Kinesis has three types:

Kinesis Streams

Shards are 5 transactions per second for reads. Can read upto 2 MB data per second. Can write 1000 records per second and max 1 MB write.

Stores data from 24 hours to 24 x 7. Data is sharded. Then shards are analyzed by EC2 Consumers. Then EC2 can store it in separate places like s3/redshift,dynamodb.

One shard can ingest up to 1000 data records per second, or 1MB/sec. Add more shards to increase your ingestion capability.

You will specify the number of shards needed when you create a stream and can change the quantity at any time.

A single shard can ingest up to 1 MiB of data per second (including partition keys) or 1,000 records per second for writes.

Each shard can support up to five read transactions per second.

Shards = Streams

Kinesis Firehose

Firehose = Streams but not persistent

No persistent storage. It triggers lambda as soon as data comes. Lambda can then send it to S3 and redshift.

Kinesis Data Firehose can convert the format of your input data from JSON to Apache Parquet or Apache ORC before storing the data in S3. Parquet and ORC are columnar data formats that save space and enable faster queries compared to row-oriented formats like JSON.

• Data delivery format:

• For data delivery to S3, Kinesis Data Firehose concatenates multiple incoming records based on buffering configuration of your delivery stream. It then delivers the records to S3 as an S3 object.
• For data delivery to Redshift, Kinesis Data Firehose first delivers incoming data to your S3 bucket in the format described earlier. Kinesis Data Firehose then issues a Redshift COPY command to load the data from your S3 bucket to your Redshift cluster.
• For data delivery to ElasticSearch, Kinesis Data Firehose buffers incoming records based on buffering configuration of your delivery stream. It then generates an Elasticsearch bulk request to index multiple records to your Elasticsearch cluster.
• For data delivery to Splunk, Kinesis Data Firehose concatenates the bytes that you send.

• Data delivery frequency

• The frequency of data delivery to S3 is determined by the S3 Buffer size and Buffer interval value that you configured for your delivery stream.
• The frequency of data COPY operations from S3 to Redshift is determined by how fast your Redshift cluster can finish the COPY command.
• The frequency of data delivery to ElasticSearch is determined by the Elasticsearch Buffer size and Buffer interval values that you configured for your delivery stream.
• Kinesis Data Firehose buffers incoming data before delivering it to Splunk. The buffer size is 5 MB, and the buffer interval is 60 seconds.

• By default, each account can have up to 50 Kinesis Data Firehose delivery streams per Region.
• The maximum size of a record sent to Kinesis Data Firehose, before base64-encoding, is 1,000 KiB.

Kinesis Analytics

• Works with firehose and streams. It can analyze data in realtime then can store it in S3 or ElasticSearch cluster.
• You can quickly build SQL queries and Java applications using built-in templates and operators for common processing functions to organize, transform, aggregate, and analyze data at any scale.
• SQL applications in Kinesis Data Analytics support two types of inputs:

• A streaming data source is continuously generated data that is read into your application for processing.
• A reference data source is static data that your application uses to enrich data coming in from streaming sources.

• Uses Apache Flink for data stream analytics
• An in-application data stream is an entity that continuously stores data in your application for you to perform processing.
• Kinesis Data Analytics provisions capacity in the form of Kinesis Processing Units (KPU). A single KPU provides you with the memory (4 GB) and corresponding computing and networking.
• Kinesis Data Analytics for Java applications provides your application 50 GB of running application storage per Kinesis Processing Unit. Kinesis Data Analytics scales storage with your application.
• The SQL code in an application is limited to 100 KB.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-kinesis/

Elastic Beanstalk

Can easily deploy applications in AWS without worrying about any infrastructure details.

You can use environment properties to pass secrets, endpoints, debug settings, and other information to your application.

You can configure your environment to use Amazon SNS to notify you of important events that affect your application.

Your environment is available to users at a subdomain of elasticbeanstalk.com. When you create an environment, you can choose a unique subdomain that represents your application.

LightSail vs Beanstalk

Lightsail is like godaddy or cpanel. It’s easier to manage things. You don’t need to know anything. Beanstalk is like heroku. It’s cloudformation template behind the scenes and creates stacks for you like RDS+EC2+Load Balancers.

Serverless / Lambda

• Lambda scales out. 1 event = 1 function. It is serverless.
• You choose the amount of memory you want to allocate to your functions and AWS Lambda allocates proportional CPU power, network bandwidth, and disk I/O.
• Supports the following languages:

• Node.js
• Java
• C#
• Go
• Python

• Lambda supports synchronous and asynchronous invocation of a Lambda function. You can control the invocation type only when you invoke a Lambda function (referred to as on-demand invocation).
• An event source is the entity that publishes events, and a Lambda function is the custom code that processes the events.
• Each Lambda function receives 500MB of non-persistent disk space in its own /tmp directory.
• AWS Lambda functions can be configured to run up to 15 minutes per execution. You can set the timeout to any value between 1 second and 15 minutes.

Lambda@Edge

• Lets you run Lambda functions to customize content that CloudFront delivers, executing the functions in AWS locations closer to the viewer. The functions run in response to CloudFront events, without provisioning or managing servers.

• You can use Lambda functions to change CloudFront requests and responses at the following points:

• After CloudFront receives a request from a viewer (viewer request)
• Before CloudFront forwards the request to the origin (origin request)
• After CloudFront receives the response from the origin (origin response)
• Before CloudFront forwards the response to the viewer (viewer response)

• You can automate your serverless application’s release process using AWS CodePipeline and AWS CodeDeploy.

Deployment Types

If you’re using the AWS Lambda compute platform, you must choose one of the following deployment configuration types to specify how traffic is shifted from the original AWS Lambda function version to the new AWS Lambda function version:

• -Canary: Traffic is shifted in two increments. You can choose from predefined canary options that specify the percentage of traffic shifted to your updated Lambda function version in the first increment and the interval, in minutes, before the remaining traffic is shifted in the second increment.
• -Linear: Traffic is shifted in equal increments with an equal number of minutes between each increment. You can choose from predefined linear options that specify the percentage of traffic shifted in each increment and the number of minutes between each increment.
• -All-at-once: All traffic is shifted from the original Lambda function to the updated Lambda function version at once.

Exam Tips

• RDS is not serverless. Dynamodb is serverless. Aurora is serverless. Functions can trigger other functions. AWS Xray allows you to debug serverless functions.

• High availability question + cost effective = serverless

• Each application is packaged with an AWS Serverless Application Model (SAM) template that defines the AWS resources used.
• Also encryption of ENV vars is done by using KMS and encryption helpers

Pricing

Duration is calculated from the time your code begins executing until it returns or otherwise terminates, rounded up to the nearest 100 milliseconds. The price depends on the amount of memory you allocate to your function.

• Free Tier: 1 million requests per month, 400,000 GB-seconds of compute time per month

• $0.20 per 1 million requests thereafter, or $0.0000002 per request

Duration pricing

• 400,000 GB-seconds per month free, up to 3.2 million seconds of compute time

• $0.00001667 for every GB-seco

References

https://docs.aws.amazon.com/lambda/latest/dg/env_variables.html#env_encrypt 

Serverless/ Lambda: https://acloud.guru/learn/aws-lambda

https://acloud.guru/learn/serverless-for-beginners

With GCP and Azure: More advanced

https://acloud.guru/learn/the-complete-serverless-course 

See this cheatsheet: https://tutorialsdojo.com/aws-cheat-sheet-aws-lambda/ 

FAQ page: https://aws.amazon.com/lambda/faqs/ 

API Gateway

• Caching capabilities
• Scales automatically
• Can throttle traffic
• Can enable CORS
• Can log requests to cloudwatch
• Together with Lambda, API Gateway forms the app-facing part of the AWS serverless infrastructure.

• API Gateway can execute Lambda code in your account, start Step Functions state machines, or make calls to Elastic Beanstalk, EC2, or web services outside of AWS with publicly accessible HTTP endpoints.
• API Gateway helps you define plans that meter and restrict third-party developer access to your APIs.
• API Gateway helps you manage traffic to your backend systems by allowing you to set throttling rules based on the number of requests per second for each HTTP method in your APIs.
• You can set up a cache with customizable keys and time-to-live in seconds for your API data to avoid hitting your backend services for each request.
• API Gateway lets you run multiple versions of the same API simultaneously with API Lifecycle.
• After you build, test, and deploy your APIs, you can package them in an API Gateway usage plan and sell the plan as a Software as a Service (SaaS) product through AWS Marketplace.
• API Gateway offers the ability to create, update, and delete documentation associated with each portion of your API, such as methods and resources.

• All of the APIs created expose HTTPS endpoints only. API Gateway does not support unencrypted (HTTP) endpoints.
• In Amazon API Gateway, stages are similar to tags. They define the path through which the deployment is accessible. For example, you can define a development stage and deploy your cars API to it. The resource will be accessible at https://www.myapi.com/dev/cars.
• Stage variables let you define key/value pairs of configuration values associated with a stage. These values, similarly to environment variables, can be used in your API configuration. For example, you could define the HTTP endpoint for your method integration as a stage variable, and use the variable in your API configuration instead of hardcoding the endpoint – this allows you to use a different endpoint for each stage (e.g. dev, beta, prod) with the same API configuration.
• Amazon API Gateway saves the history of your deployments. At any point, using the Amazon API Gateway APIs or the console, you can roll back a stage to a previous deployment.

Security and Authorization

When setting up a method to require authorization you can leverage AWS Signature Version 4 or Lambda authorizers to support your own bearer token auth strategy.

Signature v4

You can use AWS credentials - access and secret keys - to sign requests to your service and authorize access like other AWS services. The signing of an Amazon API Gateway API request is managed by the custom API Gateway SDK generated for your service. You can retrieve temporary credentials associated with a role in your AWS account using Amazon Cognito.

Lambda Authorizers

Lambda authorizers are AWS Lambda functions. With custom request authorizers, you will be able to authorize access to APIs using a bearer token auth strategy such as OAuth. When an API is called, API Gateway checks if a Lambda authorizer is configured, API Gateway then calls the Lambda function with the incoming authorization token. You can use Lambda to implement various authorization strategies (e.g. JWT verification, OAuth provider callout) that return IAM policies which are used to authorize the request. If the policy returned by the authorizer is valid, API Gateway will cache the policy associated with the incoming token for up to 1 hour.

API Endpoint Types

• Edge-optimized API endpoint: The default host name of an API Gateway API that is deployed to the specified region while using a CloudFront distribution to facilitate client access typically from across AWS regions. API requests are routed to the nearest CloudFront Point of Presence.
• Regional API endpoint: The host name of an API that is deployed to the specified region and intended to serve clients, such as EC2 instances, in the same AWS region. API requests are targeted directly to the region-specific API Gateway without going through any CloudFront distribution.

• You can apply latency-based routing on regional endpoints to deploy an API to multiple regions using the same regional API endpoint configuration, set the same custom domain name for each deployed API, and configure latency-based DNS records in Route 53 to route client requests to the region that has the lowest latency.

• Private API endpoint: Allows a client to securely access private API resources inside a VPC. Private APIs are isolated from the public Internet, and they can only be accessed using VPC endpoints for API Gateway that have been granted access.

Usage Plans

For web applications that offer personalized services, you can leverage API Gateway usage plans as well as Amazon Cognito user pools in order to scope what different sets of users have access to

A usage plan specifies who can access one or more deployed API stages and methods — and also how much and how fast they can access them.

Provides selected API clients with access to one or more deployed APIs. You can use a usage plan to configure throttling and quota limits, which are enforced on individual client API keys.

References

https://tutorialsdojo.com/aws-cheat-sheet-amazon-api-gateway/

https://aws.amazon.com/api-gateway/faqs/

https://docs.aws.amazon.com/apigateway/api-reference/ 

Lambda course

https://acloud.guru/learn/aws-lambda

Cloud Formation

• CloudFormation allows you to model your entire infrastructure in a text file called a template. You can use JSON or YAML to describe what AWS resources you want to create and configure. If you want to design visually, you can use AWS CloudFormation Designer.
• You can use Rollback Triggers to specify the CloudWatch alarm that CloudFormation should monitor during the stack creation and update process. If any of the alarms are breached, CloudFormation rolls back the entire stack operation to a previous deployed state.
• CloudFormation Change Sets allow you to preview how proposed changes to a stack might impact your running resources.
• AWS StackSets lets you provision a common set of AWS resources across multiple accounts and regions with a single CloudFormation template.
• CloudFormation artifacts can include a stack template file, a template configuration file, or both. AWS CodePipeline uses these artifacts to work with CloudFormation stacks and change sets.

• Stack Template File – defines the resources that CloudFormation provisions and configures. You can use YAML or JSON-formatted templates.
• Template Configuration File – a JSON-formatted text file that can specify template parameter values, a stack policy, and tags. Use these configuration files to specify parameter values or a stack policy for a stack.

• Drift detection enables you to detect whether a stack’s actual configuration differs, or has drifted from its expected configuration. Use CloudFormation to detect drift on an entire stack, or on individual resources within the stack.

Elements of Cloudformation template

AWS CloudFormation templates are JSON or YAML-formatted text files that are comprised of five types of elements:

1. An optional list of template parameters (input values supplied at stack creation time)

2. An optional list of output values (e.g. the complete URL to a web application)

3. An optional list of data tables used to lookup static configuration values (e.g., AMI names)

4. The list of AWS resources and their configuration values

5. A template file format version number

Template Parameters

With parameters, you can customize aspects of your template at run time, when the stack is built. For example, the Amazon RDS database size, Amazon EC2 instance types, database and web server port numbers can be passed to AWS CloudFormation when a stack is created. Each parameter can have a default value and description and may be marked as “NoEcho” in order to hide the actual value you enter on the screen and in the AWS CloudFormation event logs. When you create an AWS CloudFormation stack, the AWS Management Console will automatically synthesize and present a pop-up dialog form for you to edit parameter values.

Output Values

Output values are a very convenient way to present a stack’s key resources (such as the address of an Elastic Load Balancing load balancer or Amazon RDS database) to the user via the AWS Management Console, or the command line tools. You can use simple functions to concatenate string literals and value of attributes associated with the actual AWS resources.

References

Cloudformation: https://acloud.guru/learn/intro-aws-cloudformation 

Cloudformation labs: https://learn.acloud.guru/labs/search?vendor=AWS\&service=CloudFormation 

Cloudformation course:

https://acloud.guru/learn/intro-aws-cloudformation 

https://acloud.guru/learn/aws-advanced-cloudformation 

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-anatomy.html 

Cheatsheet: https://tutorialsdojo.com/aws-cheat-sheet-aws-cloudformation/ ( Recommended to do a course on cloudformation or do labs for clearing concepts. A Cloud Guru, introduction to cloudformation course is pretty good)

CloudWatch

cloudwatch monitors performance

cloudwatch monitors events every 5 minutes on EC2

cloudwatch alarm can create notifications

Metrics – represents a time-ordered set of data points that are published to CloudWatch.

• Exists only in the region in which they are created.
• Cannot be deleted, but they automatically expire after 15 months if no new data is published to them.
• As new data points come in, data older than 15 months is dropped.
• By default, several services provide free metrics for resources. You can also enable detailed monitoring, or publish your own application metrics.
• Metric math enables you to query multiple CloudWatch metrics and use math expressions to create new time series based on these metrics.

Dimensions – a name/value pair that uniquely identifies a metric.

• You can assign up to 10 dimensions to a metric.
• Whenever you add a unique dimension to one of your metrics, you are creating a new variation of that metric.

Statistics – metric data aggregations over specified periods of time.

Alarms – watches a single metric over a specified time period, and performs one or more specified actions, based on the value of the metric relative to a threshold over time.

You can create an alarm for monitoring CPU usage and load balancer latency, for managing instances, and for billing alarms.

When an alarm is on dashboard, it turns red when it is in the ALARM state.

Alarms invoke actions for sustained state changes only.

Alarm States

• OK—The metric or expression is within the defined threshold.
• ALARM—The metric or expression is outside of the defined threshold.
• INSUFFICIENT_DATA—The alarm has just started, the metric is not available, or not enough data is available for the metric to determine the alarm state.

When you create an alarm, you specify three settings:

• Period is the length of time to evaluate the metric or expression to create each individual data point for an alarm. It is expressed in seconds.
• Evaluation Period is the number of the most recent periods, or data points, to evaluate when determining alarm state.
• Data Points to Alarm is the number of data points within the evaluation period that must be breaching to cause the alarm to go to the ALARM state

All dashboards are global, not region-specific.

5 actions per alarm max

10 dimensions max per metric

https://tutorialsdojo.com/aws-cheat-sheet-amazon-cloudwatch/ 

CloudWatch Agent vs  SSM Agent vs Custom Daemon Scripts:

https://tutorialsdojo.com/aws-cheat-sheet-cloudwatch-agent-vs-ssm-agent-vs-custom-daemon-scripts/

CloudTrail

cloudtrail is audit based

cloudtrail monitors api calls like source ip/user of a call

View events in Event History, where you can view, search, and download the past 90 days of activity in your AWS account.

• Types

• A trail that applies to all regions – CloudTrail records events in each region and delivers the CloudTrail event log files to an S3 bucket that you specify. This is the default option when you create a trail in the CloudTrail console.
• A trail that applies to one region – CloudTrail records the events in the region that you specify only. This is the default option when you create a trail using the AWS CLI or the CloudTrail API.

• You can create a organization trail that will log all events for all AWS accounts in an organization created by AWS Organizations. Organization trails must be created in the master account.

5 trails per region max.

References

https://tutorialsdojo.com/aws-cheat-sheet-aws-cloudtrail/ 

AWS Data Pipeline

AWS Data Pipeline is a web service that helps you reliably process and move

data between different AWS compute and storage services, as well as on-premises data sources, at specified intervals. With AWS Data Pipeline, you can regularly access your data where it’s stored, transform and process it at scale, and efficiently transfer the results to AWS services such as Amazon S3, EMR, Redshift.

AWS Step Functions

AWS Step Functions lets you coordinate multiple AWS services into serverless workflows so you can build and update apps quickly. Using Step Functions, you can design and run workflows that stitch together services such as AWS  Lambda and Amazon ECS into feature-rich applications. Workflows are made up of a series of steps, with the output of one step acting as input into the next.

• AWS Step Functions is a web service that provides serverless orchestration for modern applications. It enables you to coordinate the components of distributed applications and microservices using visual workflows.
• Concepts

• Step Functions is based on the concepts of tasks and state machines.

• A task performs work by using an activity or an AWS Lambda function, or by passing parameters to the API actions of other services.
• A finite state machine can express an algorithm as a number of states, their relationships, and their input and output.

• You define state machines using the JSON-based Amazon States Language.

Step Functions = Visual Workflow + State Machines

SWF = Tasks, deciders and Actions

AWS Cost Explorer

AWS Cost Explorer has an easy-to-use interface that lets you visualize,

understand, and manage your AWS costs and usage over time. Get started

quickly by creating custom reports (including charts and tabular data) that

analyze cost and usage data, both at a high level (e.g., total costs and usage

across all accounts) and for highly-specific requests (e.g., m2.2xlarge costs

within account Y that are tagged “project: secretProject”).

• Forecasts are for three months in future.

AWS Budgets

AWS Budgets gives you the ability to set custom budgets that alert you when

your costs or usage exceed (or are forecasted to exceed) your budgeted

amount. You can also use AWS Budgets to set RI utilization or coverage

targets and receive alerts when your utilization drops below the threshold you

Define.

AWS Trust Advisor

Trusted Advisor checks the following four categories

• Cost Optimization
• Security
• Fault Tolerance
• Performance
• Service limits
• NOTICE: No HA or Access Control

KMS

Check out this AWS Key Management Service (KMS) Cheat Sheet:

https://tutorialsdojo.com/aws-cheat-sheet-aws-key-management-service-aws-kms/

AWS WAF

• A web application firewall that helps protect web applications from attacks by allowing you to configure rules that allow, block, or monitor (count) web requests based on conditions that you define.
• These conditions include:

• IP addresses
• HTTP headers
• HTTP body
• URI strings
• SQL injection
• cross-site scripting.

WAF lets you create rules to filter web traffic based on conditions that include IP addresses, HTTP headers and body, or custom URIs.

You can also create rules that block common web exploits like SQL injection and cross site scripting.

• Regular rules – use only conditions to target specific requests.
• Rate-based rules – are similar to regular rules, with a rate limit. Rate-based rules count the requests that arrive from a specified IP address every five minutes. The rule can trigger an action if the number of requests exceed the rate limit.

https://tutorialsdojo.com/aws-cheat-sheet-aws-waf/ 

http://docs.aws.amazon.com/waf/latest/developerguide/getting-started.html#getting-started-wizard-create-web-acl 

AWS Systems Manager

SSM Agent is the tool that processes Systems Manager requests and configures your machine as specified in the request. SSM Agent must be installed on each instance you want to use with Systems Manager. On some instance types, SSM Agent is installed by default. On others, you must install it manually.

Can work with containers too.

Parameter Store

• Provides secure, hierarchical storage for configuration data and secrets management.
• You can store values as plain text or encrypted data.
• Parameters work with Systems Manager capabilities such as Run Command, State Manager, and Automation.

References

https://tutorialsdojo.com/aws-systems-manager/ 

AWS Config

• A fully managed service that provides you with an AWS resource inventory, configuration history, and configuration change notifications to enable security and governance.
• Provides you pre-built rules to evaluate your AWS resource configurations and configuration changes, or create your own custom rules in AWS Lambda that define your internal best practices and guidelines for resource configurations.
• Config records details of changes to your AWS resources to provide you with a configuration history, and automatically deliver it to an S3 bucket you specify.
• Receive a notification whenever a resource is created, modified, or deleted.
• Config enables you to record software configuration changes within your EC2 instances and servers running on-premises, as well as servers and Virtual Machines in environments provided by other cloud providers. You gain visibility into:

• operating system configurations
• system-level updates
• installed applications
• network configuration

• Max number of AWS Config rules per region in your account is 50
• You can choose a retention period between a minimum of 30 days and a maximum of 7 years (2557 days).

Snowball Vs Snowball Edge

Although an AWS Snowball device costs less than AWS Snowball Edge, it cannot store 80 TB of data in one device. Take note that the storage capacity is different from the usable capacity for Snowball and Snowball Edge. Remember that an 80 TB Snowball appliance and 100 TB Snowball Edge appliance only have 72 TB and 83 TB of usable capacity respectively.

WhitePapers

https://tutorialsdojo.com/aws-well-architected-framework-five-pillars/ 

https://tutorialsdojo.com/aws-well-architected-framework-design-principles/ 

Well Architected Framework

Operational Excellence

Design Principles

Perform operations as code

Annotate Documentation

Make frequent, small, reversible changes

Refine Operations Procedures frequently

Anticipate failure

Learn from operation failures

Key AWS Services

CloudFormation

Three areas in operational excellence:

• Prepare: AWS Config and AWS Config rules can be used to create standards for

workloads and to determine if environments are compliant with those standards

before being put into production.

• Operate: Amazon CloudWatch allows you to monitor the operational health of a

Workload. The key AWS service that helps you automate response to events is AWS Lambda.

AWS Systems Manager is a collection of capabilities that helps you automate management tasks on your EC2 instances and systems in hybrid environments.

• Evolve: Amazon Elasticsearch Service (Amazon ES) allows you to analyze your log

data to gain actionable insights quickly and securely.

Security

The AWS Shared Responsibility Model enables organizations that adopt the cloud

to achieve their security and compliance goals.

Best Practices

Identity and Access Management: Use IAM and give least privilege. For API calls, prefer temporary tokens or roles.

Infrastructure protection: Use hardened AMIs and VPC

Data Protection: Use S3 with versioning. Use encryption at rest. SSL can be used in transit and can be terminated at ELB.

Incident Response: Collect logs of important stuff and Using cloudformation make clean room and isolate affected instances

Key Services

 Identity and Access Management: IAM

Detective Controls:

Cloudtrail for audit and recording API calls. AWS Config for details of infrastructure config change. Cloudwatch can trigger events to automate security responses.

Amazon GuardDuty is a managed threat detection service that continuously monitors for malicious or unauthorized behavior.

Infrastructure Protection

VPC, Use AWS Shield with Cloudfront to enable DDos Protection. AWS WAF is firewall which can protect against common web exploits.

Data protection

Encryption capability in all storage services. AWS Macie automatically discovers, classifies and protects sensitive data while KMS makes it easy to manage and create keys for encryption

Incident Response

IAM should be used to give authorization to incident response teams. Cloudformation can be used to provision a trusted environment for conducting investigation. Cloudwatch events can trigger automatic responses including calling Lambda functions.

AWS Shared Responsibility Model

AWS and customer work together towards security objectives. AWS provides secure infrastructure and services, while you, the customer, are responsible for secure operating systems, platforms, and data.

Reliability

Foundations

IAM , VPC, AWS Trusted Advisor provides visibility into service limits. AWS Shield is a managed Distributed Denial of Service (DDoS) protection service that safeguards web applications running on AWS.

Change Management

Cloudtrail, AWS Config, Amazon Auto Scaling, Cloudwatch logs and metrics

Failure Management

AWS Cloudformation provides templates for creation of AWS resouces. S3 durable for backup services. Glacier for archival. KMS for key management.

Performance Efficiency

Best Practices

Selection

Selection depends on the type of resource.

Compute

Instances, Containers and Functions. Take advantage of elasticity mechanisms.

Storage

Use S3, move between hDD to SSD in seconds.

Database

Redshift, Dynamo, RDS.

Network

Consider location. Enhanced Networking, Amazon EBS optimized instances, S3 transfer acceleration, Dynamic Cloudfront. Network features: Route 53 latency based routing, VPC endpoints, Direct Connect.

Monitoring

Cloudwatch for metrics and trigger actions through kinesis, SQS and Lambda

Trade Offs

Amazon DynamoDB Accelerator (DAX) provides a read-through/write-through distributed caching tier in front of Amazon DynamoDB, supporting the same API, but providing sub-millisecond latency for entities that are in the cache.

Cost Optimization

Expenditure Awareness

You can use Cost explorer to track where you spend, get insights. Using AWS Budgets you can get alerts of expenses increase forecast. You can tag resources to get further insight into which units you’re spending more on.

Cost Effective Resources

Use appropriate instances and resources. On-Demand Instances

allow you to pay for compute capacity by the hour, with no minimum commitments

required. Reserved Instances allow you to reserve capacity and offer savings of up

to 75% off On-Demand pricing. With Spot Instances, you can leverage unused Amazon EC2 capacity and offer savings of up to 90% off On-Demand pricing. Spot Instances are appropriate where the system can tolerate using a fleet of servers where individual servers can come and go dynamically, such as stateless web servers, batch processing, or when using HPC and big data. Use AWS Cost Explorer and Trust Advisor to regularly review usage.

Match Supply and Demand by auto scaling

Optimize over time

Keep an eye out for new features and improvements. Running RDS can be less expensive than running EC2 based db. Aurora can reduce cost.

Key services

Key service is Cost Explorer. Use Amazon CloudWatch and Trusted Advisor to help right size your resources. You can use Amazon Aurora on RDS to remove database licensing costs.

AWS Direct Connect and Amazon CloudFront can be used to optimize data transfer.

https://tutorialsdojo.com/aws-well-architected-framework-disaster-recovery/ 

AWS Best Practices

Stateless Applications

Consider putting only unique session identifier in HTTP cookie and store more detailed information on the server side. You can store this information in DynamoDB.

Store large files in shared storage like S3 or EFS to avoid introducing stateful code.

A complex multi-step workflow is another example where you must track the

current state of each execution. You can use AWS Step Functions to centrally store

execution history and make these workloads stateless.

Stateful Applications

Session Affinity

Use sticky sessions feature of Amazon Application Load Balancer. If you control client, then you can implement health checks and use service discovery to let clients connect to the same server.

Distributed Processing

Offline batch processing can be done with the help of AWS Batch, AWS Glue, and Apache Hadoop. Amazon EMR can run a load on multiple EC2 instances without operational overload. For realtime processing use Kinesis which shards data and can be consumed by EC2 and Lambda.

Disposable Resources Instead of Fixed

With AWS, prefer starting new instance/new resource with updated configuration and problem fixes than update existing one. This ensures there’s no configuration drift. You should have immutable infrastructure. Once a server is launched it’s never updated, just replaced. This makes rollbacks easier and enables software which is in consistent state.

Golden Images

Prefer creating AMIs over boot scripts or puppet/chef. This enables to launch instances faster. Golden images can also be created for RDS, EBS.

Containers

AWS Elastic Beanstalk, Amazon ECS and Amazon Fargate let you deploy and manage multiple containers on cluster of EC2 instances. You can build docker images and manage them using ECS Container Registry. EKS can be used to use Kubernetes.

Hybrid

Beanstalk follows hybrid setup where it starts from Golden AMIs but gives you control on bootstrapping using  .ebextensions configuration files. Environment variables can also be used in Beanstalk to parameterize environment differences.

Serverless Management and Deployment

AWS CodePipeline, AWS CodeBuild, and AWS CodeDeploy support the automation of

the deployment of these processes.

Amazon EC2 auto recovery

You can create an Amazon CloudWatch alarm that monitors an EC2 instance and automatically recovers it if it becomes impaired. A recovered instance is identical to the original instance, including the instance ID, private IP addresses, Elastic IP addresses, and all instance metadata. However, this feature is only available for applicable instance configurations.

See AWS Systems Manager

Auto Scaling

You can use Auto Scaling to help make sure that you are running the desired

number of healthy EC2 instances across multiple Availability Zones. Auto Scaling can

also automatically increase the number of EC2 instances during demand spikes to maintain performance and decrease capacity during less busy periods to optimize costs.

Alarms and Events

Cloudwatch can send alarm if a metric goes beyond a threshold for specified time. This alarm is sent via SNS and SNS can kick off Lambda, add message to SQS or perform HTTP, HTTPS requests to endpoints.

Cloudwatch events can be routed to one or more targets such as lambda functions, Kinesis Streams or SNS topics.

Loose Coupling

See API Gateway

Service Discovery

ELB can be used to access a stable endpoint. This can be abstracted using Route 53 so ELB hostname can be abstracted and modified at any time. Amazon Route 53 supports auto naming to make it easier to provision instances for microservices. Auto naming lets you automatically

create DNS records based on a configuration you define.

Asynchronous Integration

The two components do not integrate through direct point-to-point interaction but usually

through an intermediate durable storage layer, such as an SQS queue or a streaming

data platform such as Amazon Kinesis, cascading Lambda events, AWS Step Functions,

or Amazon Simple Workflow Service.

• Multiple heterogeneous systems use AWS Step Functions to communicate the flow of work between them without directly interacting with each other.

• Lambda functions can consume events from a variety of AWS sources, such as Amazon DynamoDB update streams and Amazon S3 event notifications. You don’t have to worry about implementing a queuing or other asynchronous integration method because Lambda handles this for you.

Serverless Architectures

See Cognito and Athena

Databases

RDS scales up and you can create read replicas. Failover takes a while before instance is available. Multi AZ is synchronous while read replicas are asynchronous. Amazon Aurora provides multi-master capability to enable reads and writes to be scaled across Availability Zones and also supports cross-Region replication.

For high writes application, consider NoSQL database. For normalized data and data with complex joins, use RDS. Large binary files should be in S3.

Search

On AWS, you can choose between Amazon CloudSearch and Amazon Elasticsearch Service (Amazon ES). Amazon CloudSearch is a managed service that requires little configuration and will scale automatically. Amazon ES offers an open-source API and gives you more control over the configuration details. Amazon ES has also evolved to become more than just a search solution. It is often used as an analytics engine for use cases such as log analytics, real-time application monitoring, and clickstream analytics. Both Amazon CloudSearch and Amazon ES use data partitioning and replication to scale horizontally. The difference is that with Amazon CloudSearch, you don’t need to worry about how many partitions and replicas you need because the service automatically handles that.

Graph Database

Amazon Neptune is a fully-managed graph database service.

Cost Optimization

Plan to implement Auto Scaling for as many Amazon EC2 workloads as possible, so that you horizontally scale up when needed and scale down and automatically reduce your spending when you don’t need that capacity anymore. In addition, you can automate turning off non-production workloads when not in use. Ultimately, consider which compute workloads you could implement on AWS Lambda so that you never pay for idle or redundant resources. Where possible, replace Amazon EC2 workloads with AWS managed services that either don’t require you to make any capacity decisions (such as ELB, Amazon CloudFront, Amazon SQS, Amazon Kinesis Firehose, AWS Lambda, Amazon SES, Amazon CloudSearch, or Amazon EFS) or enable you to easily modify capacity as and when need (such as Amazon DynamoDB, Amazon RDS, or Amazon ES).

Security

With AWS Config rules you also know if a resource was out of compliance even for a brief period of time, making both point-in-time and period-in-time audits very effective. You can implement extensive logging for your applications (using Amazon CloudWatch Logs) and for the actual AWS API calls by enabling AWS CloudTrail.

AWS Overview of Services

Information saved in services sections of relevant services.

Exam tips

AWS Managed services let you reduce time to market and lower cost and complexity. Note: no service specialization.

AWS Serverless Lens

Too much detail about Lambda. Good paper for review but may have to come back to it during Developer Associate Certification.

Security on AWS

AWS Risk and Compliance

Use AWS Artifact to access compliance reports. SOC1, SOC2, SOC3 reports can be requested and accessed on demand.

AWS Disaster Recovery

Recovery Time Objective (RTO) and Recovery Point Objective (RPO)

RTO is the time it takes to restore system after a disruption. RPO is acceptable amount of data loss measured in time. The amount of data loss a business can tolerate usually determines the desired recovery time objective.

Backup  and Restore

This is slowest option and may not meet RTO. Can be cheapest though.

The Pilot Light Disaster Recovery Method

Requires storing critical systems as a template within database. In event of disaster, resources can be scaled out from around our ‘pilot light’. Instances can be launched using AMIs.

The term pilot light is often used to describe a DR scenario in which a minimal version of an environment is always running in the cloud. The idea of the pilot light is an analogy that comes from the gas heater. In a gas heater, a small flame that’s always on can quickly ignite the entire furnace to heat up a house. This scenario is similar to a backup-and-restore scenario.

For example, with AWS you can maintain a pilot light by configuring and running the most critical core elements of your system in AWS. When the time comes for recovery, you can rapidly provision a full-scale production environment around the critical core.

Warm Standby

Warm standby is a method of redundancy in which the scaled-down secondary system runs in the background of the primary system. Doing so would not optimize your savings as much as running a pilot light recovery since some of your services are always running in the background.

Multi Site

Multi-site is the most expensive solution out of disaster recovery solutions. You are trying to save monthly costs so this should be the least probable choice for you.

References

https://d1.awsstatic.com/whitepapers/aws-disaster-recovery.pdf

https://tutorialsdojo.com/aws-cheat-sheet-backup-and-restore-vs-pilot-light-vs-warm-standby-vs-multi-site/ 

References

http://jayendrapatil.com/tag/cheat-sheet/ 

AWS Cert prepare Guide:  

https://acloud.guru/forums/aws-certified-solutions-architect-associate/discussion/-Kgy6EyakT-cTLL6mhOo/how_can_you_score_highest_in_e 

Udemy Practice Exam https://www.udemy.com/aws-certified-solutions-architect-associate-amazon-practice-exams/