chore(ci): Avoid writing to cache in workflows triggered by the merge queue

.github/actions/cache/action.yml

@@ -0,0 +1,38 @@
+name: Cache
+description: 'A wrapper around `actions/cache` which exposes an additional `read-only` input to conditionally write new cache entries'
+
+inputs:
+  path:
+    description: 'A list of files, directories, and wildcard patterns to cache and restore'
+    required: true
+  key:
+    description: 'An explicit key for restoring and saving the cache'
+    required: true
+  read-only:
+    description: 'Do not write cache artifacts in the case of a missed cache'
+    default: 'false'
+    required: false
+
+outputs:
+  cache-hit:
+    description: 'A boolean value to indicate an exact match was found for the primary key'
+    value: ${{ steps.cache.outputs.cache-hit || steps.restore.outputs.cache-hit }}
+
+runs:
+  using: composite
+  steps:
+
+    - id: restore
+      uses: actions/cache/restore@v3
+      if: ${{ inputs.read_only }}
+      with:
+        path: ${{ inputs.path }}
+        key: ${{ inputs.key }}
+
+    - id: cache
+      uses: actions/cache@v3
+      if: ${{ !inputs.read_only }}
+      with:
+        path: ${{ inputs.path }}
+        key: ${{ inputs.key }}  
+

.github/workflows/publish.yml

@@ -79,7 +79,7 @@ jobs:
           echo "SDKROOT=$(xcrun -sdk macosx$(sw_vers -productVersion) --show-sdk-path)" >> $GITHUB_ENV
           echo "MACOSX_DEPLOYMENT_TARGET=$(xcrun -sdk macosx$(sw_vers -productVersion) --show-sdk-platform-version)" >> $GITHUB_ENV
 
-      - uses: actions/cache@v3
+      - uses: ./.github/actions/cache
         with:
           path: |
             ~/.cargo/bin/
@@ -88,6 +88,7 @@ jobs:
             ~/.cargo/git/db/
             target/
           key: ${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          read-only: ${{ github.event_name == 'merge_group' }}
 
       - name: Download artifact
         uses: actions/download-artifact@v3
@@ -161,7 +162,7 @@ jobs:
         with:
           ref: ${{ inputs.tag || env.GITHUB_REF }}
 
-      - uses: actions/cache@v3
+      - uses: ./.github/actions/cache
         with:
           path: |
             ~/.cargo/bin/
@@ -170,6 +171,7 @@ jobs:
             ~/.cargo/git/db/
             target/
           key: ${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          read-only: ${{ github.event_name == 'merge_group' }}
 
       - name: Download artifact
         uses: actions/download-artifact@v3
@@ -237,7 +239,7 @@ jobs:
         with:
           ref: ${{ inputs.tag || env.GITHUB_REF }}
 
-      - uses: actions/cache@v3
+      - uses: ./.github/actions/cache
         with:
           path: |
             ~/.cargo/bin/
@@ -246,6 +248,7 @@ jobs:
             ~/.cargo/git/db/
             target/
           key: ${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          read-only: ${{ github.event_name == 'merge_group' }}
 
       - name: Download artifact
         uses: actions/download-artifact@v3

.github/workflows/test.yml

@@ -38,10 +38,11 @@ jobs:
 
       - name: Restore nix store cache
         id: nix-store-cache
-        uses: actions/cache@v3
+        uses: ./.github/actions/cache
         with:
           path: /tmp/nix-cache
           key: ${{ runner.os }}-flake-${{ hashFiles('*.lock') }}
+          read-only: ${{ github.event_name == 'merge_group' }}
 
       # Based on https://github.com/marigold-dev/deku/blob/b5016f0cf4bf6ac48db9111b70dd7fb49b969dfd/.github/workflows/build.yml#L26
       - name: Copy cache into nix store

.github/workflows/wasm.yml

@@ -54,7 +54,7 @@ jobs:
       - name: Checkout Noir repo
         uses: actions/checkout@v3
 
-      - uses: actions/cache@v3
+      - uses: ./.github/actions/cache
         with:
           path: |
             ~/.cargo/bin/
@@ -63,6 +63,7 @@ jobs:
             ~/.cargo/git/db/
             target/
           key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          read-only: ${{ github.event_name == 'merge_group' }}
 
       - name: Download artifact
         uses: actions/download-artifact@v3