Docker Layer Caching FAQ

Docker Layer Caching (DLC) can reduce Docker image build times on CircleCI by caching individual layers of any Docker images built as part of your jobs. Here are some frequently asked questions around DLC:

Is DLC available between different workflows under the same project?

Yes, DLC is not locked to workflows or jobs. You can create a maximum of 50 DLC volumes per project (including any parallelism).

Why are subsequent builds not able to access the cache consistently?

If a job fails while calling a specific DLC volume, it would require rebuilding when calling it again, causing inconsistencies. It is worth noting that different jobs may also use different volumes. An example being if two machine jobs are run in parallel, they will get different DLC volumes.

How can I delete my DLC cache instance?

DLC caches are immutable, so they cannot be selectively deleted. However, a cache will be deleted after 3 days of not being used in a project.

Is DLC guaranteed? 

DLC is not guaranteed. If you are experiencing issues with cache-misses or need high-parallelism, consider try caching using docker build, which you can optionally implement using the CircleCI Docker orb.

As an admin, can I see the content of a DLC volume?

While you can see what volume is used for each job, at this time, the content is unavailable.

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