feat(build): raise BuildKit cache-mount budget for remote builders #112

Merged

pat-s merged 1 commit from fix/buildkit-cache-mount-budget into main

2026-07-08 08:22:04 +00:00

pat-s commented

2026-07-08 08:20:46 +00:00

Owner

BuildKit's default GC caps the ephemeral cache tier — RUN --mount=type=cache mounts, local build context, git checkouts — at a hardcoded 512 MB (shown as 488.3 MiB in buildx inspect).
Across our 7-distro build matrix that fills instantly and forces re-downloads of system + R packages on every rebuild.

Changes

docker/buildkitd.toml (new) — GC config passed via --config when creating the docker-container builders artemis (amd64) and gaia (arm64):
- cache-mount tier: 512 MB → 8 GB, retained 7 days
- total cache bounded at 40 GB with 20 GB min-free
justfile — document the --config docker/buildkitd.toml flag on the builder-create commands so a recreate does not silently revert to the 512 MB default.

Notes

Limits are absolute (not %) because the two hosts differ ~6× in free space (Hetzner ~42 GiB free vs Mac mini ~279 GiB). The 20 GB min-free is the safety valve on the disk-tight Hetzner host; the old default wanted 64 GiB free, which does not exist there.
Both live builders were already recreated with this config and verified running.

BuildKit's default GC caps the ephemeral cache tier — `RUN --mount=type=cache` mounts, local build context, git checkouts — at a hardcoded **512 MB** (shown as `488.3 MiB` in `buildx inspect`). Across our 7-distro build matrix that fills instantly and forces re-downloads of system + R packages on every rebuild. ## Changes - **`docker/buildkitd.toml`** (new) — GC config passed via `--config` when creating the `docker-container` builders `artemis` (amd64) and `gaia` (arm64): - cache-mount tier: **512 MB → 8 GB**, retained 7 days - total cache bounded at **40 GB** with **20 GB min-free** - **`justfile`** — document the `--config docker/buildkitd.toml` flag on the builder-create commands so a recreate does not silently revert to the 512 MB default. ## Notes - Limits are absolute (not `%`) because the two hosts differ ~6× in free space (Hetzner ~42 GiB free vs Mac mini ~279 GiB). The 20 GB min-free is the safety valve on the disk-tight Hetzner host; the old default wanted 64 GiB free, which does not exist there. - Both live builders were already recreated with this config and verified running.

pat-s added 1 commit

2026-07-08 08:20:46 +00:00

feat(build): raise BuildKit cache-mount budget for remote builders 474a7fe62d

BuildKit's default GC caps the ephemeral cache tier (RUN
--mount=type=cache mounts, local context, git checkouts) at a hardcoded
512 MB.
Across the 7-distro build matrix that fills instantly and forces
re-downloads of system and R packages on every rebuild.

Add docker/buildkitd.toml and pass it via --config when creating the
docker-container builders (artemis/amd64, gaia/arm64):

- cache-mount tier raised 512 MB -> 8 GB, retained 7 days
- total cache bounded at 40 GB with 20 GB min-free (safe on the
  disk-tight Hetzner host, modest on the Mac mini)

Limits are absolute rather than percentages because the two hosts differ
~6x in free space. Document the --config flag in the justfile so a future
recreate does not silently revert to the 512 MB default.

pat-s merged commit 09536cddd6 into main

2026-07-08 08:22:04 +00:00

pat-s referenced this pull request from a commit

2026-07-08 08:22:04 +00:00

feat(build): raise BuildKit cache-mount budget for remote builders (#112)

pat-s deleted branch fix/buildkit-cache-mount-budget

2026-07-08 08:22:05 +00:00