scale builder tmpfs with VM memory instead of fixed 3G#207
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sjmiller609 wants to merge 1 commit intomainfrom
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scale builder tmpfs with VM memory instead of fixed 3G#207sjmiller609 wants to merge 1 commit intomainfrom
sjmiller609 wants to merge 1 commit intomainfrom
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The /var/lib/buildkit tmpfs that BuildKit's overlayfs snapshotter writes into was hardcoded at 3GB. That's enough for small alpine-based images but too tight for any build whose base image extracts to >3GB on its own — e.g. GPU-driver bases like onkernel/chromium-headful-vgpu, where the FROM extraction alone leaves no room for a single apt install. Size the tmpfs at 75% of the builder VM's MemTotal so callers who request more memory_mb actually get more snapshot headroom. Keeps the 3G fallback for tiny builders or unreadable /proc/meminfo. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
The builder agent mounts a tmpfs at
/var/lib/buildkitfor BuildKit's overlay snapshotter, hardcoded tosize=3G. That's tight: any base image plus install layer that exceeds ~3GB extracted hitsno space left on devicemid-build, even when the VM was provisioned with 16GB+ of RAM.This change scales the tmpfs to 75% of VM memory (read from
/proc/meminfo) with a 1GiB floor and a 3G fallback, so callers who pay for a larger builder VM actually get the disk budget they expect.Test plan
go vet ./...andgo build ./...inlib/builds/builder_agent(already passing locally)