Issue Summary

In Bitbucket Pipelines, docker-cached layers from previous builds are not being used in subsequent builds.

The docker cache is successfully generated and uploaded in the initial pipeline. It's downloaded in the next step, but it's not used by docker, which is building the layers from scratch.

Steps to Reproduce

1. Create a pipeline and have a step configured to do a docker build , and to use the docker pre-defined cache

   pipelines:
     custom:
       test-build-docker-image:
         - step:
             name: Build Docker image
             script:
               - docker build .
             caches:
               - docker
             services:
               - docker
   

2. Run the pipeline the first time. It will generate a cache with the docker image built layers and upload it to Bitbucket.
3. Run the pipeline a second time. It will now download the previously generated cache, but docker will not use the cache layers and will build each layer again from scratch.

Expected Results

Docker should use the cached layers from the previous build if no change was applied to that layer in the Dockerfile

Actual Results

Docker is using the previous cache layers.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available