buildx/docs/guides/cache/inline.md

Inline cache storage

The inline cache store is the simplest way to get an external cache and is easy to get started using if you're already building and pushing an image. However, it doesn't scale as well to multi-stage builds as well as the other drivers do and it doesn't offer separation between your output artifacts and your cache output. This means that if you're using a particularly complex build flow, or not exporting your images directly to a registry, then you may want to consider the registry cache.

To export your cache using inline storage, we can pass type=inline to the --cache-to option:

$ docker buildx build --push -t <user>/<image> --cache-to type=inline .

Alternatively, you can also export inline cache by setting the build-arg BUILDKIT_INLINE_CACHE, instead of using the --cache-to flag:

$ docker buildx build --push -t <user>/<image> --arg BUILDKIT_INLINE_CACHE=1 .

To import the resulting cache on a future build, we can pass type=registry to --cache-from which lets us extract the cache from inside a docker image:

$ docker buildx build --push -t <user>/<image> --cache-from type=registry,ref=<user>/<image> .

Most of the time, you'll want to have each build both import and export cache from the cache store - to do this, specify both --cache-to and --cache-from:

$ docker buildx build --push -t <user>/<image> \
    --cache-to type=inline \
    --cache-from type=registry,ref=<user>/<image>

Further reading

For an introduction to caching see Optimizing builds with cache management.

For more information on the inline cache backend, see the BuildKit README.