CodeDeploy Overview¶

• We want to deploy our application automatically to many EC2 instances
• These EC2 instances are not managed by ElasticBeanstalk
• There are several ways to handle deployments using open-source tools (Ansible, Terraform, Chef, Puppet,...)
• We can use the managed service AWS CodeDeploy

Steps to make it work¶

• Each EC2 instance/on-premises server must be running CodeDeploy Agent
• The agent is continously polling AWS CodeDeploy for work to do
• Application + appspec.yml is pulled from GitHub or S3
• EC2 instances will run the deployment instructions in appspec.yml
• CodeDeploy Agent will report of success/failure of the deployment

Primary Components¶

• Application - a unique name functions as a container (revision, deployment, configuration)
• Compute Platform - EC2/On-Premises, AWS Lambda, or Amazon ECS
• Deployment Configuration - a set of deployment rules for success/failure
  • 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, or dev, test, prod...)
• Deployment Type - method used to deploy the application to a Deployment Group
  • In-place Deployment - supports EC2/On-Premises
  • Blue/Green Deployment - supports EC2 instances only, AWS Lambda and Amazon ECS
• IAM Instance Profile - give EC2 instances the permissions to access both S3 / GitHub
• Application Revision - application code + appspec.yml file
• Service Role - an IAM Role for CodeDeploy to perform operations on EC2 instances, ASGs, ELBs...
• Target Revision - the most recent revision that you want to deploy to a Deployment Group

appspec.yml¶

• files - how to source and copy from S3 / GitHub to filesystem
  • source
  • destination
• hooks - set of instructions to do to deploy the new version (hooks can have timeouts), the order is:
  • ApplicationStop
  • DownloadBundle
  • BeforeInstall
  • Install
  • AfterInstall
  • ApplicationStart
  • ValidateService (important)

version: 0.0
os: linnux

files:
    - source: Config/config.txt
      destination: /webapps/Config
    - source: source
      destination: /webapps/myApp
hooks:
    BeforeInstall:
        - location: Scripts/UnzipResourceBundle.zip
        - location: Scripts/UnzipDataBundle.zip
    AfterInstall:
        - location: Scripts/RunResourceTests.sh
          timeout: 180
    ApplicationStart:
        - location: Scripts/RunFunctionalTests.sh
          timeout: 3600
    ValidateService:
        - location: Scripts/MonitorService.sh
          timeout: 3600
          runas: codedeployuser

Deployment Configurations¶

• Configurations:
  • On at A Time - one EC2 instance at a time, of one instance fails, then deployment stops
  • Half At A Time - 50%
  • All At Once - quick but no healthy host, downtime. Good for dev
  • Custom - min, healthy host = 75%
• Failures:
  • EC2 instances stay in failed stated
  • New deployments will first be deployed to failed instances
  • To rollback, redeploy old deployment or enable automated rollback for failures
• Deployment Groups:
  • A set of tagged EC2 instances
  • Directly to an ASG
  • Mix of ASG / Tags so you can build deployment segments
  • Customization in scripts with DEPLOYTMENT_GROUP_NAME environment variables