Amazon ECS blue/green deployments
A blue/green deployment is a release methodology that reduces downtime and risk by running two identical production environments called blue and green. With Amazon ECS blue/green deployments, you can validate new service revisions before directing production traffic to them. This approach provides a safer way to deploy changes with the ability to quickly roll back if needed.
Benefits
The following are benefits of using blue/green deployments:
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Reduces risk through testing with production traffic before switching production. You can validate the new deployment with test traffic before directing production traffic to it.
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Zero downtime deployments. The production environment remains available throughout the deployment process, ensuring continuous service availability.
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Easy rollback if issues are detected. If problems arise with the green deployment, you can quickly revert to the blue deployment without extended service disruption.
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Controlled testing environment. The green environment provides an isolated space to test new features with real traffic patterns before full deployment.
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Predictable deployment process. The structured approach with defined lifecycle stages makes deployments more consistent and reliable.
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Automated validation through lifecycle hooks. You can implement automated tests at various stages of the deployment to verify functionality.
Terminology
The following are Amazon ECS blue/green deployment terms:
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Bake time - The duration when both blue and green service revisions are running simultaneously after the production traffic has shifted.
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Blue deployment - The current production service revision that you want to replace.
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Green deployment - The new service revision that you want to deploy.
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Lifecycle stages - A series of events in the deployment operation, such as "after production traffic shift".
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Lifecycle hook - A Lambda function that verifies the deployment at a specific lifecycle stage.
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Listener - A Elastic Load Balancing resource that checks for connection requests using the protocol and port that you configure. The rules that you define for a listener determine how Amazon ECS routes requests to its registered targets.
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Rule - An Elastic Load Balancing resource associated with a listener. A rule defines how requests are routed and consists of an action, condition, and priority.
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Target group - An Elastic Load Balancing resource used to route requests to one or more registered targets (for example, EC2 instances). When you create a listener, you specify a target group for its default action. Traffic is forwarded to the target group specified in the listener rule.
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Traffic shift - The process Amazon ECS uses to shift traffic from the blue deployment to the green deployment. For Amazon ECS blue/green deployments, all traffic is shifted from the blue service to the green service at once.
Considerations
Consider the following when choosing a deployment type:
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Resource usage: Blue/green deployments temporarily run both the blue and green service revisions simultaneously, which may double your resource usage during deployments.
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Deployment monitoring: Blue/green deployments provide more detailed deployment status information, allowing you to monitor each stage of the deployment process.
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Rollback: Blue/green deployments make it easier to roll back to the previous version if issues are detected, as the blue revision is kept running until the bake time expires.