STAR Spack Package Repository

Build caches

The Dockerfile has two explicit Spack buildcache modes. In both modes, spack_cache_image defaults to ghcr.io/star-bnl/star-spack:spack-buildcache, which must contain a Spack binary mirror at /opt/spack-buildcache.

Consume the buildcache (default)

Normal builds use packages from the mirror first and compile cache misses from source. Successfully installed packages are also added to the local BuildKit cache mount named star-spack-buildcache, but no buildcache image is exported or included in the runtime image.

docker build \
  --build-arg starenv=root5 \
  --build-arg compiler=gcc11 \
  --tag star-spack:root5-gcc11 \
  .

Runtime binaries and libraries are stripped by default to minimize the final image. For a faster validation build that does not optimize image size, add --build-arg optimize_runtime=false.

To consume another compatible mirror image, override spack_cache_image=<image>. The image must provide /opt/spack-buildcache/build_cache/index.json and its referenced package archives.

Rebuild and export the buildcache

After a normal build compiles new packages, set rebuild_spack_buildcache=true and select the spack-buildcache target. The installation steps are identical in both modes, so this command can reuse the completed Spack layers from the normal build. It ensures all installed packages are present in the named cache mount, rebuilds the mirror index, and exports the updated mirror image.

docker build \
  --target spack-buildcache \
  --build-arg rebuild_spack_buildcache=true \
  --build-arg starenv=root5 \
  --build-arg compiler=gcc485 \
  --build-arg spack_cache_export_revision="$(date +%s)" \
  --tag ghcr.io/star-bnl/star-spack:spack-buildcache \
  --push .

Use the same builder for successive rebuilds: the star-spack-buildcache cache-mount ID and Docker layer cache are local to a builder. With the same builder and unchanged build inputs, switching to the spack-buildcache target does not compile the packages again. The exported image is a shared mirror, so repeat the rebuild command for each affected environment/compiler combination while pushing the same tag.

For the one-time creation of a cache when no prior image exists, add:

--build-arg spack_cache_image=spack-cache-empty-stage

In CI, every runtime build uses the default cache-first mode with source fallback. Pull requests build and test all environment/compiler combinations without stripping the runtime files and do not publish images or the local mirror. Pushes to main perform the size optimization, publish latest-<env>-<compiler> images in parallel, but do not update either cache. Tags also perform the size optimization and publish <tag>-<env>-<compiler> images without updating the caches. Run the Update Spack Buildcache workflow manually when package or environment changes require a refresh. Its matrix runs sequentially so each entry consumes the shared mirror published by the previous entry, and it also updates the separate buildkit-cache-<env>-<compiler> registry caches.