feat: Add Linux runners for all supported architectures

This change expands the existing CI/CD pipeline to include Linux builds for all supported, non-x86-32 architectures.

The following changes were made:
- Added `ubuntu-20.04` runners for `x86_64`, `aarch64`, `ppc64le`, and `s390x`.
- Integrated the `uraimo/run-on-arch-action` to facilitate builds on emulated, non-x86 architectures.
- Updated the build matrix and steps in `.github/workflows/build.yml` to support the new runners.
- Dropped support for the `x86-32` architecture as requested.

Author: google-labs-jules[bot]

.github/workflows/build.yml

@@ -56,18 +56,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-# for now I'm disabling linux building as we don't have the tooling to support it
-#        os: [ ubuntu-latest ]
-#        cpu:
-#          - k8  # this build 'linux-x86_64', is currently working but not useful without the other architectures
-# would need some kind of CROSSTOOL chain to build the other architectures
-# or we'd have to use the https://github.com/uraimo/run-on-arch-action (which lacks support for x86_32) to build these
-#          - x86_32
-#          - systemz
-#          - aarch64
-#          - ppc64
         include:
 # to ensure backwards compatibility as long as possible, use earliest versions of OSs available on Github Actions
+          - os: ubuntu-20.04
+            cpu: x86_64
+            bazel_target: dist_zip
+          - os: ubuntu-20.04
+            cpu: aarch64
+            bazel_target: dist_zip
+            arch: aarch64
+          - os: ubuntu-20.04
+            cpu: ppc64le
+            bazel_target: dist_zip
+            arch: ppc64le
+          - os: ubuntu-20.04
+            cpu: s390x
+            bazel_target: dist_zip
+            arch: s390x
           - os: windows-2022
             cpu: x64_windows
             bazel_target: dist_zip
@@ -96,13 +101,26 @@ jobs:
 
       - run: mkdir out
 
-        # setup-bazelisk fails when running in ACT because the cache is not available so we need to ignore to let the bazel step run
-      - if: success() || env.ACT && failure()
-        run: bazel build --cpu=${{ matrix.cpu }} ${{ matrix.bazel_target || 'dist_all' }}
-        shell: bash
-
-      # need to copy to output directory as `bazel-bin` is a symlink and cannot be read by the actions/upload-artifact action
-      - run: cp bazel-bin/protobuf-javascript-* out/
+      - name: Build on emulated arch
+        uses: uraimo/run-on-arch-action@v3
+        if: matrix.arch
+        with:
+          arch: ${{ matrix.arch }}
+          distro: ubuntu20.04
+          githubToken: ${{ secrets.GITHUB_TOKEN }}
+          run: |
+            # setup-bazelisk fails when running in ACT because the cache is not available so we need to ignore to let the bazel step run
+            bazel build --cpu=${{ matrix.cpu }} ${{ matrix.bazel_target || 'dist_all' }}
+            # need to copy to output directory as `bazel-bin` is a symlink and cannot be read by the actions/upload-artifact action
+            cp bazel-bin/protobuf-javascript-* out/
+
+      - name: Build on native arch
+        if: ${{ !matrix.arch }}
+        run: |
+          # setup-bazelisk fails when running in ACT because the cache is not available so we need to ignore to let the bazel step run
+          bazel build --cpu=${{ matrix.cpu }} ${{ matrix.bazel_target || 'dist_all' }}
+          # need to copy to output directory as `bazel-bin` is a symlink and cannot be read by the actions/upload-artifact action
+          cp bazel-bin/protobuf-javascript-* out/
 
       - uses: actions/upload-artifact@v4
         with: