Level up your Docker vocabulary with BuildKit's advanced features — cache mounts, linked layers, multi-stage patterns, and inline caching.
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1 / 5
A build takes 8 minutes because pip install re-runs on every push. In a PR review, you suggest adding --mount=type=cache. What does this BuildKit directive do?
RUN --mount=type=cache,target=/root/.cache/pip gives the build step a persistent directory that persists between builds on the same host, letting pip skip already-downloaded packages.
2 / 5
During a Dockerfile review, a colleague asks why you used COPY --link for static assets. The benefit is:
COPY --link makes the layer independent of previous layers — BuildKit can reuse or rebuild it in parallel without invalidating the chain, improving cache hit rates.
3 / 5
Your CI produces large images because dev dependencies end up in production. In a design discussion, the recommended BuildKit solution is:
Multi-stage builds keep build tools and dev dependencies in intermediate stages. The final stage copies only needed artifacts, producing a slim image with no build toolchain.
4 / 5
A teammate wants to share build cache between CI runners without a dedicated cache backend. In a PR, you recommend using inline cache. This means:
Inline cache (--build-arg BUILDKIT_INLINE_CACHE=1 + --cache-from) embeds cache metadata in the pushed image. A subsequent build pulling that image can reuse its layers as cache.
5 / 5
During a standup, a DevOps engineer asks how BuildKit differs from the legacy Docker builder. The most accurate summary is:
BuildKit introduces parallel stage execution, --mount types (cache, secret, ssh), COPY --link, and a content-addressable store — all unavailable in the legacy builder.