ci: Cache docker image build mounts

.forgejo/actions/rust-toolchain/action.yml

@@ -15,6 +15,10 @@ inputs:
   components:
     description: Space-separated list of components to be additionally installed for a new toolchain
     required: false
+outputs:
+  rustc_version:
+    description: The rustc version installed
+    value: ${{ steps.rustc-version.outputs.version }}
 
 runs:
   using: composite
@@ -43,3 +47,7 @@ runs:
         ${{ inputs.components && format('rustup component add {0}', inputs.components) }}
         cargo --version
         rustc --version
+    - id: rustc-version
+      shell: bash
+      run: |
+        echo "version=$(rustc --version)" >> $GITHUB_OUTPUT

.forgejo/workflows/release-image.yml

@@ -85,6 +85,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Install rust
+        id: rust-toolchain
         uses: ./.forgejo/actions/rust-toolchain
 
       - name: Set up Docker Buildx
@@ -126,6 +127,52 @@ jobs:
           key: timelord-v0
           path: .
 
+      - name: Cache Rust registry
+        uses: actions/cache@v3
+        with:
+          path: |
+            .cargo/git
+            .cargo/git/checkouts
+            .cargo/registry
+            .cargo/registry/src
+          key: rust-registry-image-${{hashFiles('**/Cargo.lock') }}
+      - name: Cache cargo target
+        id: cache-cargo-target
+        uses: actions/cache@v3
+        with:
+          path: |
+            cargo-target-${{ matrix.slug }}
+          key: cargo-target-${{ matrix.slug }}-${{hashFiles('**/Cargo.lock') }}-${{steps.rust-toolchain.outputs.rustc_version}}
+      - name: Cache apt cache
+        id: cache-apt
+        uses: actions/cache@v3
+        with:
+          path: |
+            var-cache-apt-${{ matrix.slug }}
+          key: var-cache-apt-${{ matrix.slug }}
+      - name: Cache apt lib
+        id: cache-apt-lib
+        uses: actions/cache@v3
+        with:
+          path: |
+            var-lib-apt-${{ matrix.slug }}
+          key: var-lib-apt-${{ matrix.slug }}
+      - name: inject cache into docker
+        uses: https://github.com/reproducible-containers/buildkit-cache-dance@v3.1.0
+        with:
+          cache-map: |
+            {
+              ".cargo/registry": "/usr/local/cargo/registry",
+              ".cargo/git/db": "/usr/local/cargo/git/db",
+              "cargo-target-${{ matrix.slug }}": {
+                "target": "/app/target",
+                "id": "cargo-target-${{ matrix.platform }}"
+              },
+              "var-cache-apt-${{ matrix.slug }}": "/var/cache/apt",
+              "var-lib-apt-${{ matrix.slug }}": "/var/lib/apt"
+            }
+          skip-extraction: ${{ steps.cache.outputs.cache-hit }}
+
       - name: Build and push Docker image by digest
         id: build
         uses: docker/build-push-action@v6