Blue/Green deployment is a powerful strategy for minimizing downtime and mitigating risks during application updates. By running two environments—one active (Blue) and one staging (Green)—you can switch traffic seamlessly between versions, allowing quick rollbacks if needed. This blog provides a step-by-step guide on implementing a Blue/Green deployment strategy on AWS using CodeCommit, CodeBuild, CodeDeploy, Lambda, and Systems Manager.

1. Introduction to Blue/Green Deployment Strategy

In a Blue/Green deployment, two separate but identical environments (Blue and Green) are used. The Blue environment represents the current production version, while the Green environment hosts the new version. Once the new version (Green) is verified, traffic will shift from Blue to Green. If any issues arise, the traffic can easily be reverted to Blue, ensuring zero downtime and a seamless rollback process.

2. Setting Up CodeCommit Repository

First, you must set up a repository to store your application code. AWS CodeCommit provides a scalable, managed source control service.

  • Steps:
    1. Open the AWS Management Console and navigate to CodeCommit.
    2. Create a new repository and push your application’s code into this repository using Git.
    3. Use branches (e.g., green for the new deployment) to facilitate code changes without impacting the primary blue production environment.

3. Configuring CodeBuild for Continuous Integration

AWS CodeBuild is responsible for building your application after each commit.

  • Steps:
    1. Create a building project in CodeBuild.
    2. Define a buildspec.yml file with the commands to compile, test, and package your application.
    3. Configure CodeBuild to trigger automatically on commits to the green branch.
    4. Integrate CodeBuild with CodeCommit to ensure continuous integration.

4. Creating Blue and Green Environments

The Blue and Green environments must be identical. You can use AWS services like EC2, Elastic Beanstalk, or ECS to set up these environments.

  • Steps:
    1. Use AWS CloudFormation or Terraform to create infrastructure templates.
    2. Ensure both environments are set up in different environments, such as Elastic Beanstalk applications or ECS clusters.
    3. Keep your Blue environment live and Green as the testing environment for the new version.

5. Automating Deployment with AWS CodeDeploy

AWS CodeDeploy enables automated deployments and helps manage Blue/Green transitions.

  • Steps:
    1. Configure a deployment group in CodeDeploy with Blue/Green as the deployment type.
    2. Define lifecycle hooks to ensure CodeDeploy switches traffic from Blue to Green gradually or all at once.
    3. Specify the target revision, which could be the code in the green branch of your CodeCommit repository.

6. Implementing Lambda Functions for Traffic Switching

Lambda functions can automate traffic switching between Blue and Green environments, adding flexibility and programmability to the traffic control process.

  • Steps:
    1. Write a Lambda function that updates the Route 53 DNS records to point to the Blue or Green environment.
    2. Use the AWS SDK within Lambda to switch DNS entries dynamically based on environment readiness.
    3. Ensure the Lambda function is tied to your deployment process to trigger after the Green environment is validated.

7. Orchestrating Lambda Execution with Systems Manager

AWS Systems Manager allows you to automate the execution of Lambda functions and other tasks during deployment.

  • Steps:
    1. Set up a Systems Manager document to invoke the Lambda function for traffic switching.
    2. Define a step in your deployment process that triggers this document after the Green environment passes all tests.
    3. Use Systems Manager to automate traffic switching, rollback, or other operational tasks.

8. Initiating and Monitoring Deployment

Once the setup is complete, initiate the deployment and monitor its progress.

  • Steps:
    1. Use CodeDeploy to start the Blue/Green deployment process.
    2. Monitor the deployment using CloudWatch metrics and CodeDeploy logs.
    3. Ensure health checks are performed on the Green environment before traffic is entirely shifted.

9. Efficient Rollback Procedure

Blue/Green deployment offers an easy rollback mechanism in case of any issues.

  • Steps:
    1. If a deployment to Green fails, simply invoke the Lambda function to shift traffic back to Blue.
    2. Use AWS CodeDeploy’s rollback features, which will automatically revert to the previous environment if a failure occurs.
    3. Monitor CloudWatch logs to ensure the rollback is successful and no errors persist in the Blue environment.

10. Conclusion and Best Practices

Blue/Green deployment is an effective way to deploy new application versions with minimal downtime and risk. You can automate and streamline the process by leveraging AWS services like CodeCommit, CodeBuild, CodeDeploy, Lambda, and Systems Manager. Essential best practices include:

  • Always test the Green environment thoroughly before switching traffic.
  • Automate as many processes as possible to reduce manual errors.
  • Monitor performance metrics and logs in real-time to detect issues early.

References.

Achieving Zero-downtime deployments with Amazon CloudFront using blue/green continuous deployments

Blue/Green Deployment Methodology