ci: cross-compile aarch64-apple-darwin from Linux (drop macos-latest lane) by zackees · Pull Request #771 · FastLED/fbuild

zackees · 2026-06-28T01:12:24Z

Summary

Replaces the macos-latest runner for the aarch64-apple-darwin release lane with the existing ubuntu-latest runner already shared by every other target. Uses soldr + cargo-zigbuild + soldr's managed Apple SDK to produce real Mach-O arm64 binaries from Linux x86_64. Removes the last cross-platform-runner dependency from the release matrix.

What landed

.github/workflows/release-auto.yml — aarch64-apple-darwin lane swaps to ubuntu-latest + new mac_cross_linux: true flag
.github/workflows/template_native_build.yml — adds the mac_cross_linux boolean + matching build / PyO3 / staging / strip branches
ci/docker-mac-arm64-cross/ — minimal ubuntu:24.04-based docker image + build.sh that reproduces the GHA flow locally and asserts via file(1) that all three artifacts are valid Mach-O arm64. The "NO CHEATING" local-validation gate.

How it was validated

Local docker run against current main:

staging/fbuild:          Mach-O 64-bit arm64 executable
staging/fbuild-daemon:   Mach-O 64-bit arm64 executable
staging/_native.abi3.so: Mach-O 64-bit arm64 dynamically linked shared library

Sizes: 23 MB / 25 MB / 14 MB — comparable to the macOS-native lane.

Test plan

Local docker validation: 3 Mach-O arm64 artifacts produced and verified by file(1)
Trigger GHA release; verify the aarch64-apple-darwin matrix entry succeeds on ubuntu-latest
Verify uploaded artifacts in the resulting GitHub Release are unchanged in shape (same binaries, same _native.abi3.so layout)

🤖 Generated with Claude Code

Summary by CodeRabbit

New Features
- Added support for building macOS ARM64 release artifacts from Linux, improving build flexibility and speed.
- Enabled cross-platform packaging for the app’s command-line tools and Python extension on the same release lane.
- Added a containerized workflow for reproducing the macOS ARM64 build process locally.
Documentation
- Added setup and usage instructions for the new cross-build container, including verification steps for generated binaries.

…lane) Replaces the `macos-latest` runner for the `aarch64-apple-darwin` release lane with the existing `ubuntu-latest` runner already shared by every other target. The Linux runner uses soldr + cargo-zigbuild + soldr's managed Apple SDK to produce real Mach-O arm64 binaries — closing the last cross-platform-runner dependency in the release matrix. ## What landed * `.github/workflows/release-auto.yml` — `aarch64-apple-darwin` lane swaps `runner: macos-latest` for `runner: ubuntu-latest` plus the new `mac_cross_linux: true` flag. * `.github/workflows/template_native_build.yml` — adds the `mac_cross_linux: true` boolean input + the matching build / PyO3 / staging / strip branches. When set: - `soldr prepare --target aarch64-apple-darwin` fetches the Apple SDK ahead of cargo so the SDKROOT export is debuggable independently - `soldr cargo zigbuild --release --target aarch64-apple-darwin` builds `fbuild-cli` + `fbuild-daemon` - `PYO3_NO_PYTHON=1 soldr cargo zigbuild ...` builds the `fbuild-python` PyO3 extension with the same target-dir layout the macOS native lane produced (no rename needed in stage step) - strip step is a no-op (Linux's binutils `strip` would silently corrupt a Mach-O; the binaries ship unstripped at ~25 MB each) * `ci/docker-mac-arm64-cross/` — a minimal `ubuntu:24.04`-based docker image + `build.sh` that reproduces the GHA flow locally and asserts via `file(1)` that all three output artifacts are `Mach-O 64-bit ... arm64`. The "NO CHEATING" gate that locked the workflow design. ## How it was validated Local run inside the docker image, against the current tip of FastLED/fbuild#main: ``` staging/fbuild: Mach-O 64-bit arm64 executable staging/fbuild-daemon: Mach-O 64-bit arm64 executable staging/_native.abi3.so: Mach-O 64-bit arm64 dynamically linked shared library ``` Sizes: 23 MB / 25 MB / 14 MB — comparable to the macOS-native lane. ## Known soft warnings (non-blocking) * `rust-objcopy` fails to load `libLLVM.so` during the strip-debuginfo post-link step on aarch64-apple-darwin — cargo's `profile.release.strip` knob calls rust-objcopy which expects libLLVM next to the rustc binary. Cargo treats this as a warning and the binaries are produced correctly. soldr#934's `llvm-tools-preview` work covers this when the catalogue ingest cycle wires it up. * `soldr prepare` warns about a failed internal `rustup target add` — cosmetic, the explicit `soldr rustup target add` in build.sh already added the target. Tracked separately as a soldr bug. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

coderabbitai · 2026-06-28T01:12:39Z

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The pull request is closed.

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📥 Commits

Reviewing files that changed from the base of the PR and between 15551a6 and b2e6368.

📒 Files selected for processing (5)

.github/workflows/release-auto.yml
.github/workflows/template_native_build.yml
ci/docker-mac-arm64-cross/Dockerfile
ci/docker-mac-arm64-cross/README.md
ci/docker-mac-arm64-cross/build.sh

📝 Walkthrough

Walkthrough

The aarch64-apple-darwin release lane is moved from a macOS runner to ubuntu-latest using soldr + cargo-zigbuild for cross-compilation. A new mac_cross_linux boolean flag threads through the release matrix and the native build template to gate Apple SDK preparation, zigbuild invocations, artifact staging, and strip skipping. A local Docker simulator (ci/docker-mac-arm64-cross/) with build.sh and README is added to reproduce this lane without GitHub Actions.

Changes

aarch64-apple-darwin Linux Cross-Compile Lane

Layer / File(s)	Summary
Release matrix: switch aarch64 to ubuntu + mac_cross_linux flag `.github/workflows/release-auto.yml`	`aarch64-apple-darwin` matrix entry changed from `macos-latest` to `ubuntu-latest` with `mac_cross_linux: true`; the flag is passed into the template workflow call.
template_native_build: mac_cross_linux input and build/stage/strip branches `.github/workflows/template_native_build.yml`	Declares `mac_cross_linux` boolean input; adds `soldr prepare` step for Apple SDK; routes `fbuild-cli`, `fbuild-daemon`, and `fbuild-python` through `soldr cargo zigbuild`; copies `lib_native.dylib` into `staging/_native.abi3.so`; skips binary stripping for Mach-O.
Docker image for local cross simulation `ci/docker-mac-arm64-cross/Dockerfile`, `ci/docker-mac-arm64-cross/README.md`	New `ubuntu:24.04`-based Dockerfile that installs `uv`, pinned `soldr` binaries, `cargo-zigbuild`, and `zig`, setting required env defaults. README explains purpose, build/run commands, and the Mach-O validation check.
build.sh: cross-compile, stage, and validate `ci/docker-mac-arm64-cross/build.sh`	Script bootstraps Rust via `soldr`, pre-fetches Apple SDK, builds all three crates with `soldr cargo zigbuild`, stages artifacts (renaming dylib to `_native.abi3.so`), and validates each is a Mach-O ARM64 binary via `file(1)`.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

FastLED/fbuild#760: Modifies the same release-auto.yml and template_native_build.yml for cross-compiling the aarch64-apple-darwin lane from Linux with cargo zigbuild, including the same lib_native.dylib → staging/_native.abi3.so staging pattern.
FastLED/fbuild#153: Introduces soldr integration into template_native_build.yml build workflows, directly underpinning the soldr prepare and soldr cargo zigbuild calls added in this PR.
FastLED/fbuild#16: Overlaps on the cross-compilation staging of _native.abi3.so and Mach-O-specific strip logic in template_native_build.yml for other cross targets.

Poem

🐇 Hop hop, no Mac in sight,
Ubuntu builds the ARM just right,
zigbuild soars, the Apple SDK found,
Mach-O binaries, arm64-bound!
"NO CHEATING," the file check cries—
A rabbit's cross-compile, Linux-skies! ✨

✨ Finishing Touches

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch feat/linux-cross-mac-arm64

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Triggers the autonomous release workflow. First release that cross-compiles `aarch64-apple-darwin` from `ubuntu-latest` instead of running on a `macos-latest` runner (#771). Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

setup-soldr@v0.9.62 defaults to soldr 0.7.51, which predates the \`soldr prepare\` builtin used by the new \`mac_cross_linux: true\` lane (landed in #771). The lane was failing with \`soldr: tool not found: prepare: not found on crates.io\` — soldr 0.7.51 treated \`prepare\` as a tool name and tried to fetch it from crates.io. Fix: * Bump action pin v0.9.62 → v0.9.63 (which defaults to 0.7.59) * Pin \`version: "0.7.59"\` explicitly so a future action default change doesn't silently shift build behavior. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

) soldr#1006 Lane 3. Closes the easiest remaining gap from the meta: \`x86_64-apple-darwin\` is now built from \`ubuntu-latest\` via the same \`mac_cross_linux: true\` template branch the arm64 lane already uses (landed in #771). Soldr's apple_sdk fetcher auto-picks the \`darwin-x86_64\` thin shape when the target triple matches, and \`cargo zigbuild --target x86_64-apple-darwin\` resolves SDKROOT + frameworks identically. Net effect: - fbuild's release matrix gains a 5th target (mac Intel) for the same per-release runner cost (just adds another ubuntu-latest job). - Zero \`macos-latest\` runners left in the matrix — both Apple targets cross-compile from Linux. ## Docker harness changes * Renamed \`ci/docker-mac-arm64-cross/\` → \`ci/docker-mac-cross/\` since the same image now validates both Apple targets. * \`build.sh\` takes a target as positional arg or \`TARGET=\` env var (default: aarch64-apple-darwin); per-target arch verification — \`arm64|aarch64\` for arm64 lane, \`x86_64\` for Intel lane. * Image tag bumped from \`fbuild-mac-arm64-cross\` → \`fbuild-mac-cross\` to match. ## Test plan - [x] Build docker image - [ ] Run \`bash ci/docker-mac-cross/build.sh x86_64-apple-darwin\`, verify 3 Mach-O x86_64 artifacts under staging/ - [ ] Trigger a release via version bump; verify new matrix entry ships \`fbuild-v<ver>-x86_64-apple-darwin.tar.gz\` Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

zackees merged commit a8b001c into main Jun 28, 2026
87 of 91 checks passed

zackees mentioned this pull request Jun 28, 2026

release: 2.3.4 (first Linux-cross-mac-arm64 release) #772

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zackees mentioned this pull request Jun 28, 2026

fix(rustup): discover rustup at $CARGO_HOME/bin/rustup zackees/soldr#1005

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fastled-project-sync Bot added this to FastLED Tracker Jun 28, 2026

fastled-project-sync Bot moved this to Triage in FastLED Tracker Jun 28, 2026

zackees mentioned this pull request Jun 28, 2026

Meta: complete fbuild cross-compile — all release lanes on Linux runners zackees/soldr#1006

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coderabbitai Bot mentioned this pull request Jun 28, 2026

ci: add x86_64-apple-darwin lane (Linux cross via mac_cross_linux) #775

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ci: cross-compile aarch64-apple-darwin from Linux (drop macos-latest lane)#771

ci: cross-compile aarch64-apple-darwin from Linux (drop macos-latest lane)#771
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