AWS Developer Tools


CI and CD are best practices for software development and deployment. They enable frequent software changes whilst maintaining system and service stability.

Continuous Integration (CI)

Let's say that developers are frequently interacting with a shared codebase. We need a way to ensure that any code change does not break the build or introduce new bugs into the application. With continuous integration, a build and a test framework is automatically triggered for every push. CI encourages frequent merging of code changes.

Continuous Delivery/Deployment (CD)

Continuous delivery is a development practice where merged changes are automatically build, tested, and prepared for release into staging and eventually production environments. There is usually a manual decision process to initiate deployment of new code. Continuous deployment takes this one step further and automatically deploys the new code following successful build and testing.


CodeCommit is a fully managed source control service that enables git repository hosting. With CodeCommit, data is encrypted in transit and at rest. CodeCommit has a visual interface with an online editor, repository browser, and pull requests. Note that to connect using git on command line, you'll need to give your AWS IAM user the correct permissions.


CodeDeploy is an automated deployment service which allows you to deploy application code automatically to EC2 instances, on-premise systems, and Lambda functions.

CodeDeploy integrates with various CI/CD tools like Jenkins, GitHub, Atlassian, AWS CodePipeline as well as configuration management tools like Ansible, Puppet, and Chef.


  1. Install CodeDeploy agents on your EC2 instances.
  2. Give CodeDeploy permissions to your IAM user.
  3. Create a new application and deployment group in CodeDeploy.
  4. Deploy using the CodeDeploy console!

CodeDeploy Deployment Approaches

In-Place Deployment

A rolling update, the application is stopped on each instance in turn and the latest revision is installed. The instance is out of service during this time and your capacity will be reduced. If the instances are behind a load balancer, you can configure the load balancer to stop sending requests to the instances which are being upgraded.

Blue/Green Deployment

New instances are provisioned and the latest revision is installed on the new instances. Blue represents the active deployment, green is the new release. The new instances are registered with an Elastic Load Balancer, traffic is routed to the new instances, and the original instances will be terminated.

Switching back to the original environment is faster and more reliable and is just a case of routing the traffic back to the original servers (as long as you haven't already terminated them).

CodeDeploy Terminology

  • Deployment Group: A set of EC2 instances or Lambda functions to which a new revision of the software is to be deployed.
  • Deployment: The process and components used to apply a new revision.
  • Deployment Configuration: A set of deployment rules as well as success/failure conditions used during a deployment.
  • AppSpec File: A definition of deployment actions you want AWS CodeDeploy to execute.
  • Revision: Everything needed to deploy the new version: AppSpec file, application files, executables, config files.
  • Application: Unique identifier for the application you want to deploy. To ensure the correct combination of revision, deployment configuration, and deployment group are referenced during a deployment.

CodeDeploy AppSpec File

The AppSpec File is used to define the parameters that will be used for deployment. The file structure depends on whether you are deploying to Lambda or EC2/On Premises.

AppSpec for Lambda Deployments

For Lambda deployments, the AppSpec File may be written in YAML or JSON and contains the following fields:

  • version: Reserved for future use (currently only allows 0.0).
  • resources: The name and properties of the Lambda function.
  • hooks: Lambda functions to run as validation tests.

Two hooks are available for use: BeforeAllowTraffic and AfterAllowTraffic. These are both validation tests.

AppSpec for EC2/On Premises

For EC2 and On Premises systems, the AppSpec file must be in YAML and has a slightly different set of fields:

  • version: Reserved for future use (currently only allows 0.0).
  • os: The operation system you are using.
  • files: Source and destination folders for application files.
  • hooks: Lifecycle event hooks that allow you to specify scripts that need to run at set points in the deployment lifecycle.

There are a series of hooks that are in a specific run order: BeforeBlockTraffic, BlockTraffic, AfterBlockTraffic, ApplicationStop, DownloadBundle, BeforeInstall, Install, AfterInstall, ApplicationStart ValidateService, BeforeAllowTraffic, AllowTraffic, and AfterAllowTraffic.


CodePipeline orchestrate the build, test, and even deployment of your application every time there is a change (CI/CD). With CodePipeline you model your release process as a workflow which integrates with CodeCommit, CodeBuild, CodeDeploy, Lambda, Elastic Beanstalk, CloudFormation, ECS, as well as third party tools, like GitHub and Jenkins.


CodeBuild is a fully managed build service that compiles source code, runs tests, and produces software packages that are ready to deploy.