Exam Tips

AWS CLI

• Least Privilege
• Always give your users, the minimum amount of access required to do the job.
• Use Groups
• Create IAM policy groups and assign your users to the groups. Group permissions are assigned using IAM policy documents.
• Secret access key
• You only see this ones. If you lose it you can delete the access key and secret access key and regenerate them. You need to run AWS configure again.
• Don’t share key pairs
• Each developer should have their own access Key ID and secret access Key. Just like passwords, they should not be shared.
• Supports Linux, Windows, macOS
• You can install CLI on your Mac, Linux, or Windows PC. You can also use it on EC2 instances.

AWS CLI Pagination

• If you see errors like “ timed out”, or errors related to too many results being returned.
• Adjust the pagination of CLI results to avoid errors generated by too many results.
• aws S3 api list-objects - - bucket my-bucket  - - page-size 100.
• The CLI still retrieves the full list, but performs a large number of API calls in the background and retrieves a smaller number of items with each call.

AWS Roles

• Roles are a preferred option from security perspective.
• Roles allow us to provide access without the use of access key ID and secure access keys.
• Policies, control roles permissions.
• We can update a policy attached to a role and it will take immediate effect.
• You can attach and detach roles running EC2 instance, without having to stop or terminate the instance.

AWS RDS

• RDS database types
• SQL Server, Oracle, mySQL, PostgresSQL, Maria, DB, and Amazon Aurora.
• RDS is for 0LTP workloads
• Great for processing. Lots of small transactions, like customer orders, banking, transactions, payments and booking systems.
• Not suitable for OLAP.
• Use red shift for the data warehousing and OLAP tasks, like analysing large amounts of data, reporting, and sales forecasting.

AWS SECRETS MANAGER

• Centrally manage secrets used to access resources inside and outside AWS.
• Rotate secrets without code deployment.
• Secure secrets with control of fine, grain permissions and encryption with AWS KMS.
• Secret types
• RDS database
• Red shift cluster
• Document DB database
• Other API keys

AWS EC2 IMAGE BUILDER

• EC2 image builder automates the process of creating and maintaining AMI and container images.
• It is a 4 step process
• Select a base OS image.
• Customised by adding software.
• Test and distribute to your chosen region.
• Terminology
• Image pipeline
• Settings and process.
• Image recipe
• Image and build components.
• Build components
• The software that you want to include.

Version control with lambda

• $Latest is always the last version of Code. You want to upload to lambda.
• Versioning and aliases
• Use lambda, versioning and Alias is to point your applications to a specific version if you don’t want to use $Latest.
• Example ARN
• ARN of lambda:$Latest
• arm of lambda:prod
• If your application uses an alias instead of $Latest, remember that it will not automatically use the new code when you upload it.

Lambda Concurrent executions limit

• 1000 concurrent executions per second.
• If you hit the limit, you will see invocation being rejected – 429 HTTP status code.
• The remedy is to get the limit raised by AWS support.
• Reserve concurrency guarantees, a certain number of concurrent executions are always available to a critical function.

Lambda and VPC access

• We can have lambda to access VPC resources
• It is possible to enable lambda to access resources that are inside a private VPC.
• VPC config information
• VPC ID, private Subnet ID, security group ID.
• Network access
• Lambda creates elastic network interfaces using IP’s from the private Subnets. The security group allows your function to access the resources in the VPC.

AWS Server-less

• Server-less architectures are event driven and asynchronous
• An event or message might trigger an action, but no response is expected or required.
• Think of AWS SERVICES as building blocks that can be Integrated together to create an application.
• Event driven architectures are loosely, coupled services like SQS allows you to queue messages.
• Event bridge helps you to handle events and route them to application components.
• Flexibility and scalability
• Services and components operate and scale independently of each other.

AWS Step functions

• Great way to visualize your server-less application.
• Step functions automatically trigger and track each step.
• The output of one step is often the input of next step.
• Step functions log the state of each step, so if something goes wrong you can track what went wrong, and where.
• There are two types of step function workflows.
• Standard workflows
• Long running up to 1 year
• At most once
• Non-Idempotent
• Express workflows
• Short lived up to 5 minutes
• At least once
• Idempotent
• Synchronous express workflows
• The workflow must complete before the Next step begins example confirm successful payment before sending an order.
• Asynchronous express workflows
• Other tasks are not dependent on the completion of the workflow example a messaging system.