# BuildKit GC config for the remote buildx builders (artemis/amd64, gaia/arm64).
#
# Apply when creating the docker-container builders:
#   docker buildx create --name artemis --driver docker-container \
#     --config docker/buildkitd.toml ssh://<user@host-amd64>
#   docker buildx create --name gaia    --driver docker-container \
#     --config docker/buildkitd.toml ssh://<user@host-arm64>
#
# Why: 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 every rebuild. The first rule below raises that tier.
#
# Limits are absolute (not %) on purpose: artemis and gaia have very
# different free space (Hetzner ~42 GiB free vs Mac mini ~279 GiB), so a
# percentage would mean wildly different real budgets. minFreeSpace = 20 GB
# keeps the tight Hetzner host safe while staying modest on the Mac mini.

[worker.oci]
  gc = true

  # Tier 1 — ephemeral caches (cache mounts, local context, git checkouts).
  # Raised from the 512 MB default to 8 GB, retained for 7 days so weekly
  # rebuilds reuse downloaded packages instead of re-fetching them.
  [[worker.oci.gcpolicy]]
    filters = [
      "type==source.local",
      "type==exec.cachemount",
      "type==source.git.checkout",
    ]
    keepDuration = "168h"
    maxUsedSpace = "8GB"

  # Tier 2 — everything else (image layers, RUN exec results). Bounds the
  # whole buildkit cache and always leaves 20 GB free on the host disk.
  [[worker.oci.gcpolicy]]
    all = true
    reservedSpace = "2GB"
    maxUsedSpace = "40GB"
    minFreeSpace = "20GB"