Make GH Actions less reliant on TL mirror availability

.github/workflows/main.yaml

@@ -13,6 +13,23 @@ on:
 # requests get tested even if their branch comes from a fork.
 
 jobs:
+  # Update the TeX Live tree if necessary
+  texlive-cache:
+    runs-on: ubuntu-20.04
+    name: Update TeX Live
+    outputs:
+      cache_key: ${{ steps.texlive.outputs.cache_key }}
+    steps:
+      # Boilerplate
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Install TeX Live
+        id: texlive
+        uses: zauguin/install-texlive@v3
+        with:
+          # List the required TeX Live packages in a separate file to allow reuse in
+          # different workflows.
+          package_file: .github/tl_packages
   # The l3build job contains the actual work. We misuse the matrix mechanism to
   # create three jobs which only differ in minimal elements.
   # For tags we do not run this since we run the release job instead.
@@ -72,18 +89,20 @@ jobs:
             l3build_cmd: cd required && l3build doc -q -H --show-log-on-error
             artifact_name: Documentation
     name: ${{ matrix.name }}
+    needs: texlive-cache
     steps:
       # Boilerplate
       - name: Checkout repository
         uses: actions/checkout@v3
       # We need Ghostscript for dvips and XeTeX tests.
       - run: sudo apt-get update && sudo apt-get install ghostscript
-      - name: Install TeX Live
-        uses: zauguin/install-texlive@v2
+      - name: Restore TeX Live from cache
+        uses: actions/cache/restore@v3
         with:
-          # List the required TeX Live packages in a separate file to allow reuse in
-          # different workflows.
-          package_file: .github/tl_packages
+          path: ~/texlive
+          key: ${{ needs.texlive-cache.outputs.cache_key }}
+          fail-on-cache-miss: true
+      - run: echo $HOME/texlive/bin/x86_64-linux >> $GITHUB_PATH
       - name: Run l3build
         run: ${{ matrix.l3build_cmd }}
       # Now we create the artifacts: There are two cases where this happens.

.github/workflows/trigger.yaml

@@ -0,0 +1,55 @@
+name: Manually refresh caches
+
+on:
+  workflow_dispatch:
+    inputs:
+      repository:
+        default: ctan
+        description: 'Repository URL'
+        required: false
+        type: string
+      delete-old:
+        default: false
+        description: 'Delete all caches'
+        required: false
+        type: boolean
+
+jobs:
+  rebuild-cache:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+      contents: read
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v3
+
+      - name: Clean old caches
+        run: |
+          gh extension install actions/gh-actions-cache
+          
+          REPO="${{ github.repository }}"
+          BRANCH="${{ github.ref }}"
+          HASH_KEY="texlive-0-${{ hashFiles(".github/tl_packages") }}-"
+          DATE="$(date -I)"
+
+          if ${{ inputs.delete-old }}
+          then
+            HASH_KEY="$HASH_KEY-$DATE"
+          fi
+          set +e
+          gh actions-cache list -R "$REPO" -B "$BRANCH" --key "$HASH_KEY" | cut -f 1 | while read -r cacheKey
+          do
+            gh actions-cache delete "$cacheKey" -R "$REPO" -B "$BRANCH" --confirm
+          done
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Install TeX Live
+        id: texlive
+        uses: zauguin/install-texlive@v3
+        with:
+          # List the required TeX Live packages in a separate file to allow reuse in
+          # different workflows.
+          accept-stale: false
+          repository: ${{ inputs.repository }}
+          package_file: .github/tl_packages