CodeDeploy fundamentals and appspec.yml

Automating Deployments on AWS

Dunieski Otano

Amazon Web Services Solutions Architect

What CodeDeploy does

• Releases code to EC2, Lambda, or ECS
• Pulls the build artifact from S3, GitHub, or Bitbucket
• Runs your deployment script through lifecycle events
• Rolls back automatically if something fails

CodeDeploy core components

• Application: a name that groups deployments
• Deployment group: which targets receive the release
• Deployment configuration: how the rollout proceeds (instance batches or traffic shift)
• Revision: the artifact bundle being deployed

Meet appspec.yml

• YAML file at the root of the revision
• version: 0.0 and os: linux required at the top
• Tells CodeDeploy which files go where
• Tells CodeDeploy what to run, and when

Lifecycle events on EC2

• You write: ApplicationStop, BeforeInstall, AfterInstall
• You write: ApplicationStart, ValidateService
• System runs: DownloadBundle, Install
• Each hook is a shell or PowerShell script on the instance

Lifecycle events on Lambda

• Lambda has only two hooks: BeforeAllowTraffic, AfterAllowTraffic
• Hooks are Lambda functions, not shell scripts
• CodeDeploy shifts the alias to the new version
• No instances to log into; no files to copy

A real appspec.yml for EC2

• version: 0.0 and os: linux at the top
• files: copy app.zip contents to /var/www/app
• BeforeInstall, AfterInstall, ApplicationStart: lifecycle scripts
• ValidateService: smoke-test confirms success

Let's practice!

Automating Deployments on AWS