feat: Add disk cache garbage collection to setup-bazel-cache

.github/workflows/test-setup-bazel-cache.yml

@@ -50,6 +50,13 @@ jobs:
         with:
           unique-cache-name: ${{ github.workflow }}-${{ github.job }}
 
+      - name: Print ~/.bazelrc
+        shell: bash
+        run: |
+          set -euo pipefail
+          echo "~/.bazelrc contents:"
+          cat "${HOME}/.bazelrc"
+
       - name: Verify ~/.bazelrc was written by action with cache configuration
         shell: bash
         run: |
@@ -70,8 +77,20 @@ jobs:
             exit 1
           fi
 
-          echo "~/.bazelrc contents:"
-          cat "${HOME}/.bazelrc"
+          if ! grep -Fq -- "--experimental_disk_cache_gc_max_age=" "${HOME}/.bazelrc"; then
+            echo "ERROR: ~/.bazelrc does not contain experimental_disk_cache_gc_max_age configuration"
+            exit 1
+          fi
+
+          if ! grep -Fq -- "--experimental_disk_cache_gc_max_size=" "${HOME}/.bazelrc"; then
+            echo "ERROR: ~/.bazelrc does not contain experimental_disk_cache_gc_max_size configuration"
+            exit 1
+          fi
+
+          if ! grep -Fq -- "--experimental_disk_cache_gc_idle_delay=" "${HOME}/.bazelrc"; then
+            echo "ERROR: ~/.bazelrc does not contain experimental_disk_cache_gc_idle_delay configuration"
+            exit 1
+          fi
 
       - name: Run bazel info to verify workspace and cache configuration are valid
         shell: bash

setup-bazel-cache/README.md

@@ -8,10 +8,20 @@ Bazel builds can be slow. Caching helps — but only if the cache is set up corr
 steps:
   - uses: eclipse-score/cicd-actions/setup-bazel-cache@<sha>
     with:
-      unique-cache-name: ${{ github.workflow }}-${{ github.job }} [-matrix-uid]
+      unique-cache-name: [${{ github.workflow }}-]${{ github.job }}[-<matrix-uid>]
+      # Optional parameters with default values:
+      main-branch: main
+      disk_cache_gc_max_size: 5G
 ```
 
-Using `github.workflow` and `github.job` together gives each job its own cache automatically. Append a matrix identifier if the same job runs with different configurations that produce different build outputs.
+Parameters:
+
+- unique-cache-name: A unique name for the cache. This is required to avoid conflicts between different jobs and workflows.
+  Using `github.workflow` and `github.job` together gives each job its own cache automatically.
+  Append a matrix identifier if the same job runs with different configurations that produce different build outputs.
+  Omit `github.workflow` if you use `workflow_call` triggers and want to avoid nesting caches under the caller's workflow name.
+- main-branch: The branch that is allowed to save the cache. Override if your default branch has a different name.
+- disk_cache_gc_max_size: Maximum size of the Bazel disk cache. Set to 0 for unlimited.
 
 ## Required permissions
 

setup-bazel-cache/action.yml

@@ -24,6 +24,11 @@ inputs:
     required: false
     default: "main"
 
+  disk_cache_gc_max_size:
+    description: Maximum size of the Bazel disk cache. Set to 0 for unlimited. Default is 5G, which is big enough for a standard build of communication (uses 3.6GB).
+    required: false
+    default: "5G"
+
   # Non stable API, subject to change without deprecation. Not intended for public use.
   _bazelisk_cache:
     description: For debugging purposes only.
@@ -60,3 +65,12 @@ runs:
         repository-cache: ${{ inputs._repository_cache }} # true
         cache-optimized: ${{ inputs._cache_optimized }} # true
         external-cache: ${{ inputs._external_cache }} # false
+
+    - name: Setup Bazel Cache
+      shell: bash
+      run: |
+        echo "Bazel Cache: Configuring Bazel disk cache retention time (60 days)..."
+        echo "common --experimental_disk_cache_gc_max_age=60d" >> ~/.bazelrc
+        echo "Bazel Cache: Configuring Bazel disk cache max size (${{ inputs.disk_cache_gc_max_size }})..."
+        echo "common --experimental_disk_cache_gc_max_size=${{ inputs.disk_cache_gc_max_size }}" >> ~/.bazelrc
+        echo "common --experimental_disk_cache_gc_idle_delay=0m" >> ~/.bazelrc