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lora.vegas/Dockerfile
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Run every lint-class check inside Docker (closes #38)
Add a root Dockerfile.lint that carries the checks as build steps -- a
`lint` stage running `hugo --minify --printPathWarnings` and a
`fmt-check` stage running the prettier check -- and reduce script/lint
and script/fmt-check to building their stage. A successful build is a
clean check. There is no host path and deliberately no "am I already
inside a container?" branch, which would be a host lint path in
disguise.

The two stages share a `base` whose first four instructions are
byte-identical to the main Dockerfile's, so the expensive
`RUN script/bootstrap` layer that compiles the pinned Hugo from source
is a cache hit against the main image instead of a second build of the
same thing.

Resolve the resulting recursion by splitting the checks by where they
run, not with an escape hatch. `make check` runs script/lint, so the
main Dockerfile can no longer `RUN make check`: that would be
docker-in-docker inside a bare Alpine with no docker client and no
daemon socket, and script/cibuild is what CI runs on every push. The
main Dockerfile therefore runs `make test`, the production build, and
script/cibuild builds it and then calls script/lint and
script/fmt-check. CI still covers the production build, lint and the
format check, and it runs exactly what a developer runs.

script/fmt stays on the host because it rewrites the working tree,
which a container build cannot do. That makes it the authoritative
copy of the prettier version, scope and flags that the fmt-check stage
duplicates; both sides carry a keep-in-sync note. The duplication is
forced: any `RUN script/fmt-check` inside the image is the recursion
again.

Caching is waived for the checks in the shape this repo already
settled: `ARG CHECK_EPOCH` with no default, declared and guarded
separately in each stage because ARG does not cross a FROM, with the
value expanded into the checked command as well as the guard so
invalidation does not rest on BuildKit's treatment of an unreferenced
ARG. All four image-building entrypoints now generate and pass it --
script/cibuild, script/docker, script/lint, script/fmt-check.

Verified: two consecutive script/lint runs on an unchanged tree both
executed hugo for real, with script/bootstrap CACHED; a constant-epoch
counterfactual restored the false green (exit 0, lint layer CACHED, no
hugo output); an empty epoch failed closed on the guard; a broken
template failed the lint stage and an unformatted README failed the
fmt-check stage, both reverted and re-run clean; script/cibuild and
`make check` are green with all three checks demonstrably executing.
2026-08-10 12:52:56 +00:00

56 lines
2.7 KiB
Docker

# Hugo static-site build image. The build runs `make test` -- a clean
# `hugo --minify` production build -- so the image build fails on any
# template, content or config error.
#
# It deliberately does NOT run `make check`. `make check` runs
# script/lint, and script/lint is a `docker build` of Dockerfile.lint,
# so `RUN make check` here would be docker-in-docker inside a bare
# alpine with no docker client and no daemon socket. The checks are
# therefore split by where they run: the production build here, lint and
# the prettier format check in Dockerfile.lint. Do not reintroduce a
# `make check` (or a `make lint` / `make fmt-check`) line in this file.
#
# CI coverage is unaffected: script/cibuild builds this image and then
# calls script/lint and script/fmt-check, so every check in `make check`
# still runs on every push -- see script/cibuild.
#
# Build this only via script/cibuild or script/docker: both pass the
# CHECK_EPOCH build argument that this file requires, and a bare
# `docker build .` fails by design. See the guard below for why.
# alpine 3.21, 2026-02-28
FROM alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
WORKDIR /src
# Install build dependencies first so the layer caches until the
# scripts change (script/bootstrap installs git, make, go, hugo,
# node/npm). Hugo is not an apk package here: script/bootstrap builds
# the exact pinned version with `go install`, hash-verified against
# sum.golang.org, so the published artifact does not depend on whatever
# hugo this base image's repos happen to serve.
COPY script/ script/
RUN script/bootstrap
COPY . .
# CHECK_EPOCH is a per-invocation nonce supplied by script/cibuild and
# script/docker. Without it an unchanged tree serves this layer from
# cache and the build reports a green it never ran. ARG is stage-scoped,
# so it must be redeclared in every stage that runs checks - this image
# has one stage, so one declaration. Declared with no default: a default
# would be a constant, and a constant is a stable cache key. The guard
# makes a bare `docker build .` fail loudly instead of silently reusing
# the empty (and therefore stable) cache key. Expand the value into the
# command so the cache miss does not depend on BuildKit's handling of an
# unreferenced ARG. Both the guard and the check RUN reference the value,
# so both are value-keyed: there are two independent invalidation points
# here, not one. Keep both.
#
# Everything above this point still caches, so the script/bootstrap
# layer - which compiles Hugo from source - is not rebuilt.
ARG CHECK_EPOCH
RUN [ -n "$CHECK_EPOCH" ] || exit 1
# Run the production build - build fails if the site does not build.
RUN echo "check epoch: ${CHECK_EPOCH}" && make test