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Add amd64/arm64 cross-compilation for the rax binary

Aiho Tehisaru requested to merge feature/multiarch-build into trunk

Summary

  • New make build-amd64 / build-arm64 / build-all targets cross-compile the rax binary for either architecture from either an amd64 or arm64 build host. Pure GOOS/GOARCH env vars, CGO_ENABLED=0 pinned explicitly — no cross C toolchain, no qemu needed, since modernc.org/sqlite has no cgo dependency. Verified both binaries build and make clean removes all of them (rax, rax-linux-amd64, rax-linux-arm64).
  • .gitignore updated for the new arch-suffixed binary names.
  • README documents the cross-compile targets.

Docker image: still amd64-only, and why

I initially tried making the Dockerfile itself multi-arch (--platform=$BUILDPLATFORM + TARGETOS/TARGETARCH build args) but hit a real problem: hop179's own base images (cr.klab.sh/base/go:1.26.3, cr.klab.sh/base/abi:edge) are published as single-arch amd64 manifests, no arm64 variant. Building with --platform linux/arm64 against them doesn't fail — buildx silently falls back to the amd64 base under QEMU emulation and mislabels the resulting image as arm64 (Docker itself warns InvalidBaseImagePlatform — confirmed by actually running the build). The binary inside would likely still run (it's static), but the image is not a real multi-arch image and the mismatch is exactly the kind of thing that bites someone later.

That's a base-image gap outside this repo — either cr.klab.sh/base/go/abi:edge need an arm64 variant published, or the runner stage would need to move off them to a genuinely multi-arch minimal base (e.g. scratch/distroless, since the binary is fully static). Left the Dockerfile as-is (amd64-only, unchanged) and documented the binary cross-build as the current arm64 deployment path in the README, with the base-image gap noted as a follow-up for whoever maintains cr.klab.sh.

Test plan

  • gofmt -l . clean
  • go build ./..., go vet ./..., go test ./...
  • make build-amd64 / make build-arm64 / make build-all — both binaries build successfully
  • make clean removes all built binaries
  • Confirmed via docker buildx build --platform linux/arm64 . that the Dockerfile's base images are amd64-only (reverted that experiment; not shipping it)

🤖 Generated with Claude Code

https://claude.ai/code/session_01U9buZPRQy7YXLodkSPFFik

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