fix: improve CI cache (#7)

.bazeliskrc

@@ -1,2 +1 @@
-BAZELISK_HOME=.cache/bazelisk
 USE_BAZEL_VERSION=7.1.1

.github/workflows/unit-tests.yml

@@ -10,6 +10,12 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  # Location to store the bazelisk executable
+  BAZELISK_BIN_DIR: .bazelisk-bin
+  # Version of the bazelisk to use
+  BAZELISK_VERSION: v1.19.0/bazelisk-linux-amd64
+
 jobs:
   unit-tests:
     runs-on: ubuntu-22.04
@@ -18,12 +24,42 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ github.head_ref }}
-      - name: Install bazelisk
+      - name: Get build cache key
+        id: build-cache-key
+        run: |
+          echo "key=${{ runner.os }}-build-${{ hashFiles('**') }}" \
+            >> "${GITHUB_OUTPUT}"
+      - name: Try to restore build cache
+        uses: actions/cache/restore@v4
+        with:
+          path: .cache
+          key: ${{ steps.build-cache-key.outputs.key }}
+          restore-keys: ${{ runner.os }}-build-
+      - name: Try to restore bazelisk binary
+        id: cache-bazelisk-bin
+        uses: actions/cache/restore@v4
+        with:
+          path: ${{ env.BAZELISK_BIN_DIR }}
+          key: ${{ env.BAZELISK_VERSION }}-bazelisk-bin
+      - name: Install bazelisk if it's needed
+        if: steps.cache-bazelisk-bin.outputs.cache-hit != 'true'
         run: |
-          bazelisk_dir="$(realpath "$(mktemp -d -p .)")"
-          wget https://github.com/bazelbuild/bazelisk/releases/download/v1.19.0/bazelisk-linux-amd64 \
-            -O "${bazelisk_dir}/bazelisk"
-          chmod +x "${bazelisk_dir}/bazelisk"
-          echo "${bazelisk_dir}" >> "${GITHUB_PATH}"
+          mkdir -p ${{ env.BAZELISK_BIN_DIR }}
+          wget https://github.com/bazelbuild/bazelisk/releases/download/${{ env.BAZELISK_VERSION }} \
+            -O "${{ env.BAZELISK_BIN_DIR }}/bazelisk"
+          chmod +x "${{ env.BAZELISK_BIN_DIR }}/bazelisk"
+      - name: Save bazelisk binary
+        uses: actions/cache/save@v4
+        if: steps.cache-bazelisk-bin.outputs.cache-hit != 'true'
+        with:
+          path: ${{ env.BAZELISK_BIN_DIR }}
+          key: ${{ env.BAZELISK_VERSION }}-bazelisk-bin
+      - name: Add bazelisk to PATH
+        run: echo "${{ env.BAZELISK_BIN_DIR }}" >> "${GITHUB_PATH}"
       - name: Run unit tests
         run: ./execute_tests.bash
+      - name: Save build cache
+        uses: actions/cache/save@v4
+        with:
+          path: .cache
+          key: ${{ steps.build-cache-key.outputs.key }}

.gitignore

@@ -1,3 +1,6 @@
 # Bazel
 /bazel-*
 MODULE.bazel.lock
+
+# For CI
+/.bazelisk-bin

execute_tests.bash

@@ -9,6 +9,7 @@ BAZEL_EXECUTABLE=(
     "env"
     "-i"
     BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
+    BAZELISK_HOME=.cache/bazelisk
     "HOME=${HOME}"
     "PATH=${PATH}"
     bazelisk