Intro

• AWS managed CD server to automatically deploy the latest version of the application.
• To use CodeDeploy, we first need to create an Application (in CodeDeploy console) with the correct compute platform configured. Then, create a Deployment Group with the compute resource tagged. Then, we can create a deployment with the correct application build artifact.

Components

• Application - the build artifact (archived) we want to deploy
• Compute Platform - what platform the application will be deployed to
  • EC2 or On-Premises (CodeDeploy Agent must be installed)
  • AWS Lambda
  • Amazon ECS
• Deployment Configuration - set of deployment rules for successful deployment
  • EC2/On-premises - specify the minimum number of healthy instances for the deployment
  • AWS Lambda or Amazon ECS - specify how traffic is routed to your updated versions
• Deployment Group - group of tagged EC2 instances (allows to deploy gradually, ex: first deploy to dev, then test and then prod)
• IAM Instance Profile - give EC2 instances the permissions to access S3 or GitHub
• Application Revision = build artifact + appspec.yaml file
• Service Role - IAM Role for CodeDeploy to perform operations on EC2 instances, ASGs, ELBs for deployment
• Target Revision - the most recent revision that you want to deploy to a Deployment Group

Workflow

• The developer or CI server builds and pushes the application revision (build artifact + appspec.yaml) on S3 or GitHub.
• The developer triggers a new deployment in CodeDeploy.
• The CodeDeploy Agent running on the compute resource continuously polls CodeDeploy to check if a new deployment needs to be done.

• The build artifact and appspec.yaml are downloaded to the compute resource and the CodeDeploy Agent runs the deployment instructions mentioned in appspec.yaml.

appspec.yaml

• Specifies how the build artifact should be deployed.
• Should be present at the root of the bundle.
• files - what to copy from S3 or GitHub into the deployment server
• hooks - set of instructions to deploy the new application version:
  • ValidateService (checks if the application is running properly after installation)
• Can have timeouts in any step (hook)
• hooks section for EC2 instances is shown to the right.

• Order of hooks for different compute resources
  • Lambda: BeforeAllowTraffic > AfterAllowTraffic
  • EC2: BeforeInstall → AfterInstall → ApplicationStart → ValidateService
  • ECS: BeforeInstall → AfterInstall → AfterAllowTestTraffic → BeforeAllowTraffic → AfterAllowTraffic