engine-build.yml

# Engine CI workflow that compiles engine using build-docker-v2 scripts with
# https://namespace.so/ GitHub Actions Runners.
#
# The worklow has multiple layers of caching for ccache compilation objects:
#
# - Local cache on runner's machine SSD disk, very efficient but prone to
#   cache misses when workflow can't be scheduled next to the storage
# - Remote, higher latency, S3 based storage using Cloudflare R2 bucket
# - For pull requests only: GitHub Actions Cache archive build by mounting
#   overlay filesystem on top of two other read-only caches (because pull
#   requests can't have write access for security reasons) to reduce build
#   times for subsequent pushes to the same PR branch.
#
# Because ccache can't use S3 based storage directly, we are leveraging
# bazel-remote project that supports it, and ccache supports storing artifacts
# in bazel remote caching HTTP layout.

name: Build Engine v2
on:
  workflow_dispatch:
    inputs:
      recache:
        description: "Recache ccache build objects"
        type: boolean
        default: false
  pull_request:
    paths-ignore:
      - 'doc/**'
  push:
    branches:
      - master
      # TODO: add release branches once their naming is finalized
    paths-ignore:
      - 'doc/**'
jobs:
  build-engine:
    if: github.repository == 'beyond-all-reason/spring' || github.event_name == 'workflow_dispatch'
    strategy:
      matrix:
        system:
          - amd64-linux
          - amd64-windows
    runs-on:
      # Run on 8 core, 16GiB ubuntu 24.04 machine.
      - nscloud-ubuntu-24.04-amd64-8x16-with-cache
      # Mount named cache volume `engine-${{ matrix.system }}`.
      - nscloud-cache-tag-engine-${{ matrix.system }}
      # The cache volume should be 20GiB (minimal size).
      - nscloud-cache-size-20gb
      # Also cache the git checkouts in datacenter local namespace git mirror
      # to speed them up.
      - nscloud-git-mirror-5gb
      # Also cache docker pulls in volume so images don't have to be pulled
      # and unpacked every time.
      - nscloud-exp-container-image-cache
    steps:
      - name: Checkout code
        uses: namespacelabs/nscloud-checkout-action@v5
        with:
          # We fetch full history because engine automatic version naming uses
          # that.
          fetch-depth: 0
          submodules: recursive
          dissociate: true
          path: src
      - name: Setup ccache cache
        uses: namespacelabs/nscloud-cache-action@v1
        with:
          path: |
            bazel-remote-data
            tools
      - name: Restore pull request's bazel remote cache overlay
        id: pr-cache-restore
        if: github.event_name == 'pull_request'
        uses: actions/cache/restore@v4
        with:
          path: bazel-remote-data-overlay.tar
          key: pr-bazel-remote-data-${{ matrix.system }}-${{ github.run_id }}
          restore-keys: pr-bazel-remote-data-${{ matrix.system }}-
      - name: Mount bazel remote overlay
        id: mount-overlay
        if: github.event_name == 'pull_request'
        run: |
          sudo apt-get install --yes fuse-overlayfs
          sudo tar --acls --xattrs --xattrs-include='*' -xf bazel-remote-data-overlay.tar || mkdir bazel-remote-data-overlay
          mkdir -p overlay-workdir bazel-remote-data-merged
          sudo fuse-overlayfs -o lowerdir=bazel-remote-data,upperdir=bazel-remote-data-overlay,workdir=overlay-workdir bazel-remote-data-merged
      - name: Start remote ccache fetcher
        uses: JarvusInnovations/background-action@2428e7b970a846423095c79d43f759abf979a635  # v1.0.7
        env:
          BAZEL_REMOTE_S3_ENDPOINT: ${{ vars.R2_ACCOUNT_ID }}.r2.cloudflarestorage.com
          BAZEL_REMOTE_S3_BUCKET: ${{ vars.R2_BUCKET_BUILD_CACHE }}
          BAZEL_REMOTE_S3_ACCESS_KEY_ID: ${{ github.event_name == 'pull_request' && vars.R2_RO_ACCESS_KEY_ID || vars.R2_ACCESS_KEY_ID }}
          BAZEL_REMOTE_S3_SECRET_ACCESS_KEY: ${{ github.event_name == 'pull_request' && vars.R2_RO_ACCESS_KEY_SECRET || secrets.R2_ACCESS_KEY_SECRET }}
        with:
          run: |
            if ! sha256sum --status -c <<< "8679a76074b1408a95d2b3ec0f5b1a6d0c20500cfc24c3a87ef08c1b60200f8c tools/bazel-remote"; then
              curl -L https://github.com/buchgr/bazel-remote/releases/download/v2.4.4/bazel-remote-2.4.4-linux-x86_64 -o bazel-remote
              chmod +x bazel-remote
              mv bazel-remote tools/bazel-remote
            fi

            cat > remote_ccache.conf <<EOF
            max_size = 10G
            cache_dir = /build/cache
            remote_storage = http://127.0.0.1:8085|layout=bazel
            remote_only = true
            EOF

            tools/bazel-remote \
              --dir bazel-remote-data${{ github.event_name == 'pull_request' && '-merged' || '' }} \
              --s3.auth_method access_key \
              --s3.region auto \
              --max_size 5 \
              --num_uploaders ${{ github.event_name == 'pull_request' && '0' || '100' }} \
              --disable_http_ac_validation \
              --http_address 127.0.0.1:8085 \
              --access_log_level none &
          # The magic URL below in wait-on is a special "empty object" cache
          # address that is always present, and exists exactly for the purpose
          # of health checking.
          wait-on: |
            http-get://127.0.0.1:8085/cas/e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
      - name: Pull builder image
        run: docker pull ghcr.io/${{ github.repository_owner }}/recoil-build-${{ matrix.system }}:latest
      - name: Build
        # Instead of manually running docker, it would be cool to just run whole GitHub actions
        # in container, but unfortunately ubuntu 18.04 is just too old to be able to do it ;(.
        run: |
          mkdir -p artifacts
          docker run -i --rm \
            -v /etc/passwd:/etc/passwd:ro \
            -v /etc/group:/etc/group:ro \
            --user="$(id -u):$(id -g)" \
            -v $(pwd)/src:/build/src:ro \
            -v $(pwd)/remote_ccache.conf:/build/ccache.conf:ro \
            -v $(pwd)/artifacts:/build/artifacts:rw \
            -e CCACHE_${{ inputs.recache && 'RECACHE' || 'NORECACHE' }}=1 \
            --network host \
            ghcr.io/${{ github.repository_owner }}/recoil-build-${{ matrix.system }}:latest \
            bash <<EOF
          set -e
          cd /build/src/docker-build-v2/scripts
          ./configure.sh
          ./compile.sh
          ./split-debug-info.sh
          ./package.sh

          EOF
      # TODO: Commented as this step is at the moment useless because artifacts
      # are neither publickly accesible nor used in any next steps so for now
      # it's more of an example that needs to be changed to something useful.
      # - name: Save
      #   if: github.event_name != 'pull_request'
      #   uses: namespace-actions/upload-artifact@v0
      #   with:
      #     name: output-${{ matrix.system }}
      #     path: ./artifacts
      - name: Unmount bazel remote overlay
        if: always() && steps.mount-overlay.outcome == 'success'
        run: |
          sudo fusermount -u bazel-remote-data-merged
          # Overlayfs depends on xattrs etc so we need to package it ourselves.
          sudo tar --acls --xattrs --xattrs-include='*' -cf bazel-remote-data-overlay.tar bazel-remote-data-overlay
      - name: Save pull request's bazel remote cache overlay
        id: pr-cache-save
        if: always() && steps.pr-cache-restore.outcome == 'success'
        uses: actions/cache/save@v4
        with:
          path: bazel-remote-data-overlay.tar
          key: ${{ steps.pr-cache-restore.outputs.cache-primary-key }}