Austin's SWE Notes 😭

    CodeDeploy

    • To deploy the application automatically to EC2 instances or on-premises server
      • Note: They must be running CodeDeploy Agent
    • The AWS CodeDeploy Agent will continuously polling AWS CodeDeploy for work to do
      • They pull Application and appspec.yml from Github or S3
        • appspec.yml should be at the root of the project
          • files: Copy some extra files from S3 and Github to the filesystem
            • source: The source to copy from
            • destination: destination to paste to
          • hooks: set of instructions to do to deploy the new version. Can have timeouts. Follows the following order
            • ApplicationStop
            • DownloadBundle
            • BeforeInstall
            • Install
            • AfterInstall
            • Application Start
            • ValidateService (Important)
              • To make sure the service is working correctly
    • Agent then run the deployment instruction in appspec.yml
      • And then report success/failure status
        Pasted image 20221001154023.png

    Primary components

    • Application

      • unique name for the application

    • Compute platform

      • EC2, on premises, Lambda, ECS

    • Deployment Configuration

      • Set of rules for success/failure. For example
        • EC2/On-premises: minimum of healthy instances
        • AWS Lambda / ECS: traffic is routed to the new instance
        • When Failure happens
          • EC2 instances will stay in failed
          • New deployments will first be deployed to failed instances
          • We can rollback, redeploy old deployment or enable automated rollback for failures
      • One At A time
        • Deploy 1 EC2 instance at a time. If one fails, then deployment stops
      • Custom
        • Can specify min healthy instances = 75%
      • All At Once
        • Quick but downtime, good for dev
      • Half At A time
        • We go 50% one by one
        • Pasted image 20221001155700.png

    • Deployment group

      • Group of EC2 instances (set of tagged EC2 instances)
      • ASG
      • Mix of ASG and Tags
      • Customisation in scripts with DEPLOYMENT_GROUP_NAME environment variables

    • Deployment type

      • In-place deployment
        • Supports by EC2, On-premises, ASG
        • For ASG, newly created EC2 instance will also get automatically deployed
        • For In-place deployment we have the above (all-at-one, half-at-one, one at a time)
      • Blue/Green Deployment
        • Supports by EC2, AWS Lambda and EC2
        • Use another ASG to deploy
        • If everything is healthy then v1 will be taken downPasted image 20221001160017.png

    • IAM instance profile

      • For EC2 to get permissions to access S3 and Github

    • Application Revision

      • Application code + appspect.yml

    • Service Role

      • IAM Role for CodeDeploy to perform operations on EC2 instance

    • Target Revision

      • Most recent revision that you want to deploy

    Redeploy & Rollback

    • Can be rollback
    • We can disable rollbacks to not perform rollbacks as well
    • Note: If rollback happens, it will redeploy the last known good revision.
      • If we do an in-place upgrade, we need to re-deploy the original version. Only blue-green allow you to rollback.
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