Summary
Layers built inside a FROM DOCKERFILE block do not benefit from --save-inline-cache / --use-inline-cache. Local BuildKit layer caching works fine — the issue is specifically that the inline cache mechanism does not appear to cover layers produced by the Dockerfile frontend.
Minimal reproduction
# images/node/Dockerfile
FROM public.ecr.aws/amazonlinux/amazonlinux:2023-minimal@sha256:13bffb7...
RUN microdnf -y install ca-certificates curl-minimal jq && \
microdnf clean allVERSION 0.8
node-image:
FROM DOCKERFILE -f ./images/node/Dockerfile .
SAVE IMAGE --push ghcr.io/example/node:latestearthly --use-inline-cache --save-inline-cache --push +node-image
On a fresh runner (no local BuildKit cache), the microdnf install layer rebuilds every time despite nothing in the Dockerfile having changed.
Question
Is there something we need to pass through to BuildKit (e.g. BUILDKIT_INLINE_CACHE=1 or equivalent) so that the Dockerfile frontend embeds inline cache metadata into its layers? Or is this a known limitation of FROM DOCKERFILE?
Workaround
Converting to native Earthfile FROM + RUN commands makes inline caching work as expected.
Summary
Layers built inside a
FROM DOCKERFILEblock do not benefit from--save-inline-cache/--use-inline-cache. Local BuildKit layer caching works fine — the issue is specifically that the inline cache mechanism does not appear to cover layers produced by the Dockerfile frontend.Minimal reproduction
On a fresh runner (no local BuildKit cache), the
microdnf installlayer rebuilds every time despite nothing in the Dockerfile having changed.Question
Is there something we need to pass through to BuildKit (e.g.
BUILDKIT_INLINE_CACHE=1or equivalent) so that the Dockerfile frontend embeds inline cache metadata into its layers? Or is this a known limitation ofFROM DOCKERFILE?Workaround
Converting to native Earthfile
FROM+RUNcommands makes inline caching work as expected.