aws-ecs-codedeploy-blue-green

To set up ECS blue/green deployments with ALB, define two target groups (blue and green) and configure a single listener rule to shift traffic by weight. This approach uses ALB-native weighted routing to enable zero-downtime rollouts.

ALB weighted routing minimizes operational overhead by using native listener rules for traffic shifting, whereas CodeDeploy provides reference patterns for deployment configs and rollback strategies. You should prefer ALB routing unless your existing CI/CD pipelines explicitly require CodeDeploy.

Yes, you can achieve canary-style traffic shifting by configuring weighted target groups on your ALB. This setup supports gradual traffic shifts and optional sticky sessions to safely roll out new ECS service versions.

When using Terraform for ECS blue/green deployments, apply lifecycle.ignore_changes to prevent Terraform from reverting deployment configurations managed by CodeDeploy or ALB weight updates. This ensures your automated rollouts remain stable.

CodeDeploy is not strictly required if you use ALB-native weighted routing for traffic management. However, CodeDeploy reference patterns are included to support automated rollback strategies and canary-like traffic shifts when integrated with existing deployment pipelines.