BuildKit Cache Warming

BuildKit Cache Warming

How it works

Use remote images to warm the cache

Image layers will be downloaded as needed

Same syntax using --cache-from


Cache information must be embedded during build

Docker 19.03

Demo: BuildKit Cache Warming

Build image with cache information:

docker build \
    --tag localhost:5000/test:1 \
    --build-arg BUILDKIT_INLINE_CACHE=1 \
docker push localhost:5000/test:1

Build with remote cache:

docker system prune --all
docker build \
    --cache-from localhost:5000/test:1 \

Demo: BuildKit Cache Internals

Check manifest for cache information:

curl --silent \
    -H "Accept: application/vnd.docker.distribution.manifest.v2+json" \
    localhost:5000/v2/test/manifests/1 \
    | jq --raw-output '.config.digest' \
    | while read CONFIG_DIGEST; do \
        curl --silent \
            -H "Accept: application/vnd.docker.container.image.v1+json" \
            localhost:5000/v2/test/blobs/${CONFIG_DIGEST} \
        | jq --raw-output '."moby.buildkit.cache.v0"' \
        | base64 -d \
        | jq; \