Why is my ElastiCache service update marked as "Complete" when I didn't apply the updates?

Resolution

When you don't apply an update, ElastiCache still marks a service update as Complete in the following scenarios.

You missed an optional update that expired

If you didn't apply an optional service update before the expiration date, then ElastiCache marks the update as Complete. When you set the Auto-Update after Due Date field to no, ElastiCache doesn't automatically update the service.

For clusters that are part of compliance programs, the cluster must apply all service updates. Nodes that ElastiCache launches after the release date of a service update automatically receive previous updates.

For more information, see the Can I opt out of service updates? section on Amazon ElastiCache managed maintenance and service updates help page.

ElastiCache replaced your nodes because of maintenance or a failover

If a planned maintenance event or node failover occurs, then ElastiCache provisions new nodes that include the latest service updates. ElastiCache then marks the status of the service updates for the new nodes as Complete.

The replacement nodes that ElastiCache provisions can include security patches that ElastiCache later releases as service updates to other users. For users that receive the security patches, ElastiCache marks the campaign status as Complete for the replaced nodes. After ElastiCache marks service updates as Complete, all cluster nodes have the required software patches. Your ElastiCache cluster continues to operate with the updated nodes, and you don't need to take further action.

Note: If there are existing nodes in the cluster that ElastiCache doesn't update, then it's a best practice to manually apply the updates on the existing nodes.