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AWS CodeDeploy

Updated Jul 26, 2020 ·
NOTES

This is not an exhaustive documentation of all the existing AWS Services. These are summarized notes that I used for the AWS Certifications.

To see the complete documentation, please go to: AWS documentation

Overview​

AWS CodeDeploy is a fully managed deployment service that automates software deployments to various compute services, such as Amazon Elastic Compute Cloud (EC2), Amazon Elastic Container Service (ECS), AWS Lambda, and your on-premises servers. Use CodeDeploy to automate software deployments, eliminating the need for error-prone manual operations.

  • Deploy our application automatically to multiple EC2 instances.

  • These instances are not managed by Elastic Beanstalk.

  • There are several ways to handle deployments using open source tools (Ansible, Terraform, Chef, Puppet, etc...).

  • CodeDeploy is the alternative to these tools.

How it works​

  • Each EC2 Machine (or On Premise machine) must be running the CodeDeploy Agent.
  • The agent is continuously polling AWS CodeDeploy for work to do.
  • CodeDeploy sends appspec.yml file.
  • Application is pulled from GitHub or S3.
  • EC2 will run the deployment instructions.
  • CodeDeploy Agent will report of success/failure of deployment on the instance.

Additional information​

  • EC2 instances are grouped by deployment group (dev/test/prod).
  • Lots of flexibility to define any kind of deployments.
  • CodeDeploy can be chained into CodePipeline and use artifacts from there.
  • CodeDeploy can re-use existing setup tools, works with any application, auto scaling integration.
  • Note: Blue / Green only works with EC2 instances (not on premise).
  • Support for AWS Lambda deployments (we’ll see this later).
  • CodeDeploy does not provision resources.

Primary Components​

  • Application: unique name
  • Compute platform: EC2/On-Premise or Lambda.
  • Deployment configuration: Deployment rules for success / failures.
    • EC2/On-Premise: we can specify the minimum number of healthy instances for the deployment.
    • AWS Lambda: specify how traffic is routed to our updated Lambda function versions.
  • Deployment group: group of tagged instances (allows to deploy gradually).
  • Deployment type: In-place deployment or Blue/green deployment:
  • IAM instance profile: need to give EC2 the permissions to pull from S3 / GitHub.
  • Application Revision: application code + appspec.yml file.
  • Service role: Role for CodeDeploy to perform what it needs.
  • Target revision: Target deployment application version.

CodeDeploy AppSpec​

  • File section: how to source and copy from S3 / GitHub to filesystem
  • 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: really important
    • BeforeAllowTraffic
    • AllowTraffic
    • AfterAllowTraffic

Deployment Config​

  • Configs

    • One a time: one instance at a time, one instance fails => 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

    • Instances stay in “failed state”.
    • New deployments will first be deployed to “failed state” instances.
    • To rollback: redeploy old deployment or enable automated rollback for failures.

  • Deployment Targets

    • Set of EC2 instances with tags.
    • Directly to an ASG.
    • Mix of ASG / Tags so we can build deployment segments.
    • Customization in scripts with DEPLOYMENT_GROUP_NAME environment variables.

Deployment types​

  • In place deployment

  • Blue / Green Deployment

    • Attached to one auto scaling group of instances.
    • New auto scaling group of instances created (green).
    • If it passes the health checks, version 1 (original asg) is deleted (blue).

CodeDeploy to EC2​

  • We define how to deploy the application using appspec.yml + deployment strategy.
  • CodeDeploy will do in-place updates to EC2 our fleet of instances.
  • We can use hooks to verify the deployment after each deployment phase.

CodeDeploy to ASG​

  • In place updates

    • CodeDeploy updates the current EC2 instances.
    • Instances newly created by ASG will also get automated deployments.

  • Blue / green deployment

    • A new auto-scaling group is created (settings are copied from the existing one).
    • We can choose for how long we keep the old instances.
    • Blue/Green deployment in order to work we must be using an ELB.

Rollbacks​

  • In some situation we have to roll back our deployment to a previous working version.
  • We can specify automated rollback options:
    • We may want to rollback when deployment fails.
    • We may want to rollback when a CloudWatch alarm threshold is met.
    • We can disable rollbacks entirely.
  • If a rollback happens, CodeDeploy will redeploy the last known good revision as a new deployment - new version number.