Shard CI (bazel-contrib#266)

CI is currently unbearably slow because it runs each config
sequentially.

Instead, run them in parallel. This also opens up matrix support to be
able to run more OSes (because we should test on Windows, which
increasingly is starting to work :))

.github/workflows/examples.yaml

@@ -0,0 +1,41 @@
+name: Examples
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  examples:
+    strategy:
+      matrix:
+        runs-on:
+          - ubuntu-latest
+
+    runs-on: ${{ matrix.runs-on }}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: bazelbuild/setup-bazelisk@v2
+
+      - name: Mount bazel action cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel"
+          key: bazel
+
+      - name: Mount bazel repo cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel-repo"
+          key: bazel-repo
+
+      - name: bzlmod tests and lints
+        env:
+          # Bazelisk will download bazel to here, ensure it is cached between runs.
+          XDG_CACHE_HOME: ~/.cache/bazel-repo
+        run: (cd examples/tests_and_lints && bazel --bazelrc=../../.github/workflows/ci.bazelrc test --enable_bzlmod //...)

.github/workflows/gazelle_examples.yaml

@@ -0,0 +1,41 @@
+name: Gazelle Examples
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  gazelle_examples:
+    strategy:
+      matrix:
+        runs-on:
+          - ubuntu-latest
+
+    runs-on: ${{ matrix.runs-on }}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: bazelbuild/setup-bazelisk@v2
+
+      - name: Mount bazel action cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel"
+          key: bazel
+
+      - name: Mount bazel repo cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel-repo"
+          key: bazel-repo
+
+      - name: bzlmod gazelle
+        env:
+          # Bazelisk will download bazel to here, ensure it is cached between runs.
+          XDG_CACHE_HOME: ~/.cache/bazel-repo
+        run: (cd examples/gazelle && bazelisk --bazelrc=../../.github/workflows/ci.bazelrc run --enable_bzlmod //:gazelle && bazelisk --bazelrc=../../.github/workflows/ci.bazelrc test --enable_bzlmod //...)

.github/workflows/tests.yaml

@@ -0,0 +1,55 @@
+name: Tests
+
+# Controls when the action will run.
+on:
+  # Triggers the workflow on push or pull request events but only for the main branch
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        runs-on:
+          - ubuntu-latest
+        flags:
+          - ""
+          - --config=jdk11
+          - --noenable_bzlmod
+
+    # The type of runner that the job will run on
+    runs-on: ${{ matrix.runs-on }}
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-java@v4
+        with:
+          distribution: "zulu"
+          java-version: "21"
+
+      - uses: bazelbuild/setup-bazelisk@v2
+
+      - name: Mount bazel action cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel"
+          key: bazel
+
+      - name: Mount bazel repo cache
+        uses: actions/cache@v2
+        with:
+          path: "~/.cache/bazel-repo"
+          key: bazel-repo
+
+      - name: bazel test //... (Java ${{ matrix.java-major-version }})
+        env:
+          # Bazelisk will download bazel to here, ensure it is cached between runs.
+          XDG_CACHE_HOME: ~/.cache/bazel-repo
+        run: bazelisk --bazelrc=.github/workflows/ci.bazelrc test ${{ matrix.flags }} //...