Add workflow for caching-pixi-lock

https://github.com/marketplace/actions/setup-pixi#only-save-caches-on-main

Author: VeckoTheGecko

.github/workflows/benchmarks.yml

@@ -9,7 +9,10 @@ env:
   PR_HEAD_LABEL: ${{ github.event.pull_request.head.label }}
 
 jobs:
+  cache-pixi-lock:
+    uses: ./.github/workflows/cache-pixi-lock.yml
   benchmark:
+    needs: cache-pixi-lock
     if: ${{ contains( github.event.pull_request.labels.*.name, 'run-benchmark') && github.event_name == 'pull_request' || contains( github.event.pull_request.labels.*.name, 'topic-performance') && github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch' }}
     name: Linux
     runs-on: ubuntu-latest
@@ -24,6 +27,18 @@ jobs:
         with:
           fetch-depth: 0
 
+      - name: Restore cached pixi lockfile
+        uses: actions/cache/restore@v4
+        id: restore-pixi-lock
+        with:
+          path: |
+            pixi.lock
+          key: ${{ needs.cache-pixi-lock.outputs.cache-id }}
+      - uses: prefix-dev/setup-pixi@v0.9.0
+        with:
+          cache: true
+          cache-write: ${{ github.event_name == 'push' && github.ref_name == 'main' }}
+
       - name: Set up conda environment
         uses: mamba-org/setup-micromamba@v2
         with:

.github/workflows/cache-pixi-lock.yml

@@ -0,0 +1,49 @@
+name: Generate and cache Pixi lockfile
+
+on:
+  workflow_call:
+    outputs:
+      cache-id:
+        description: "The lock file contents"
+        value: ${{ jobs.cache-pixi-lock.outputs.cache-id }}
+
+jobs:
+  cache-pixi-lock:
+    name: Generate output
+    runs-on: ubuntu-latest
+    outputs:
+      cache-id: ${{ steps.restore.outputs.cache-primary-key }}
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+          sparse-checkout: pixi.toml
+      - name: Get current date
+        id: date
+        run: echo "date=$(date +'%Y-%m-%d')" >> "$GITHUB_OUTPUT"
+      - uses: actions/cache/restore@v4
+        id: restore
+        with:
+          path: |
+            pixi.lock
+          key: ${{ steps.date.outputs.date }}_${{hashFiles('pixi.toml')}}
+      - uses: prefix-dev/setup-pixi@v0.9.0
+        if: ${{ !steps.restore.outputs.cache-hit }}
+        with:
+          pixi-version: v0.49.0
+          run-install: false
+      - name: Run pixi lock
+        if: ${{ !steps.restore.outputs.cache-hit }}
+        run: pixi lock
+      - uses: actions/cache/save@v4
+        if: ${{ !steps.restore.outputs.cache-hit }}
+        id: cache
+        with:
+          path: |
+            pixi.lock
+          key: ${{ steps.restore.outputs.cache-primary-key }}
+      - name: Upload pixi.lock
+        uses: actions/upload-artifact@v4
+        with:
+          name: pixi-lock
+          path: pixi.lock

.github/workflows/ci.yaml

@@ -32,10 +32,13 @@ jobs:
         id: detect-trigger
         with:
           keyword: "[skip-ci]"
+
+  cache-pixi-lock:
+    uses: ./.github/workflows/cache-pixi-lock.yml
   test:
     name: ${{ matrix.os }} py${{ matrix.python-version }} ${{ matrix.env }}
     runs-on: ${{ matrix.os }}
-    needs: detect-ci-trigger
+    needs: [detect-ci-trigger, cache-pixi-lock]
     if: needs.detect-ci-trigger.outputs.triggered == 'false'
     defaults:
       run:
@@ -82,6 +85,18 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0 # Fetch all history for all branches and tags.
+      - name: Restore cached pixi lockfile
+        uses: actions/cache/restore@v4
+        id: restore-pixi-lock
+        with:
+          path: |
+            pixi.lock
+          key: ${{ needs.cache-pixi-lock.outputs.cache-id }}
+      - uses: prefix-dev/setup-pixi@v0.9.0
+        with:
+          cache: true
+          cache-write: ${{ github.event_name == 'push' && github.ref_name == 'main' }}
+
       - name: Set environment variables
         run: |
           echo "TODAY=$(date +'%Y-%m-%d')" >> $GITHUB_ENV