Overview

When using Docker Layer Caching (DLC) in AWS, the image layers are saved using separate external volumes of Elastic Block Store (EBS) and attached to the instances running machine and Remote Docker jobs. This allows for re-use of docker images across jobs to optimize build times.

Solution

First, confirm that projects are using docker_layer_caching.

The EBS volumes are used when docker_layer_caching is set as true for a project. To support docker layer caching, the volumes are not removed until a period of inactivity (by default, 3 days) has elapsed.

It is possible to enable faster removal of the volumes by shortening the threshold for inactivity.

In your values.yaml, you can specify under the vm_service block a dlc_lifespan_days spec which will allow the cleanup to happen more often. 

vm_service:
  dlc_lifespan_days: 3
  providers:
    ...

Please note that jobs that utilize DLC may experience fewer cache hits if you are clearing DLC faster than you can create it.

Additional Resources:

• Enabling Docker Layer Caching
• Updating Replicated
• vm_service.dlc_lifespan_days