aws codedeploy features

CodeDeploy offers CICD in various ways, these were covered in a previous note that had an overview of the different code hosting solutions that AWS offers.

More nitty gritty features

• In-place deployment:
  • capacity is reduced during the deployment
  • Lambda is not supported
  • Rolling back involves a re-deploy
  • Great when deploying the first time
• Blue/Green deployment:
  • No capacity reduction (safest option)
  • Green instances can be created ahead of time
  • Easy to switch between old and new
  • You pay for 2 environments until you terminate the old servers

CodeDeploy AppSpec file

• AppSpec file - Configuration file for the parameters to be used during the CodeDeploy

deployment

• For EC2 and on-premises systems the file is YAML only
• For Lambda YAML and JSON are supported

EC2 AppSpec file structure

• version - reserved for future use (0.0 is only value now)
• OS - operating system version you're using (linux, windows, etc.)
• files - config files, packages, locations of where files are and should be copied to
• hooks - lifecycle event hooks, aka scripts that need to run during the deployment

lifecycle. Hooks have a specific run order

Example scripts during a deployment:

• Unzip application files
• Run tests on a newly deployed application
• Deal with load balancing - de-register and re-register instances with a load balancer

Example EC2 appspec.yml:

Typical folder structure for CodeDeploy is:

• appspec.yml
• /Scripts
• /Config
• /Source

Note: The appspec.yml file needs to be in the root directory

AppSpec lifecycle event hooks

Lifecycle event hooks happen in 3 phases during a deployment.

• Phase 1:
  • De-register instances from a load balancer
• Phase 2:
  • Nuts and bolts of the application deployment
• Phase 3:
  • Re-register instances with the load balancer

Phase 1

The following are in order of execution for lifecycle event hooks before deployment:

• BeforeBlockTraffic:
  • Tasks that youw ant to run on instances before they are deregistered from
  a load balancer
• BlockTraffic:
  • Block - de-register instances from a load balancer
• AfterBlockTraffic:
  • Tasks you want to run on instances after they are de-registered from a load
  balancer

Phase 2

Run order for an in-place deployment:

• ApplicationStop - gracefully stop the application
• DownloadBundle - CodeDeploy agent copies application files to a temp location
• BeforeInstall - pre-installation scripts, like backing up a current version, decrypting files
• Install - copy application revision files to final location
• AfterInstall - post-install scripts like configuration, file permissions, etc.
• ApplicationStart - start any services that were stopped during ApplicationStop
  • Could be a script or set of commands to run
• ValidateService - run tests to validate the service

Phase 3

The following hooks are run after the app is installed:

• BeforeAllowTraffic - tasks to run on instances before they're registered with the

load balancer

• AllowTraffic - register instances with the load balancer
• AfterAllowTraffic - things to run after registering with the load balancer