ECS Changes? #198
Description
Keep an eye on these upcoming changes and see if we need to do anything:
Hello,
We are reaching out to inform you about an upcoming change to Amazon Elastic Container Service (ECS) that enhances how ECS services maintain high availability across Availability Zones (AZs).
Effective June 30, 2025, Availability Zone (AZ) rebalancing will be enabled by default for all newly created ECS services that are compatible with the feature.
What is AZ Rebalancing?
AZ rebalancing helps improve application availability by automatically monitoring and distributing ECS tasks evenly across Availability Zones. When ECS detects an imbalanced task distribution across AZs, it will proactively launch tasks in the AZs with the fewest tasks and terminate excess tasks in the AZs with the most tasks.
What is Changing?
* Starting June 30, 2025, ECS will default enableAvailabilityZoneRebalancing to true for all new ECS Services that are compatible with the feature.
* Existing services (created before June 30, 2025) will not be affected by this change.
* Services that are not compatible — such as those using the binpack placement strategy — will default to false to ensure backward compatibility.
Important Considerations:
* AZ rebalancing may involve stopping and starting tasks as part of the rebalancing process. If you have workloads that are sensitive to task termination or require strict control over task placement, you may want to opt out by setting enableAvailabilityZoneRebalancing to false when creating new services.
* To enable AZ rebalancing on existing compatible services, update Service and set enableAvailabilityZoneRebalancing to true.
We encourage you to review your ECS service configurations to determine compatibility and decide if any changes are needed for your specific workloads.
For detailed documentation on AZ rebalancing, including compatibility requirements and usage examples, please refer to the ECS Developer Guide [1].
If you have any questions or need support, please do not hesitate to contact AWS Support [2].
[1] https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-rebalancing.html
[2] https://aws.amazon.com/support
Sincerely,
Amazon Web Services