Parallelize release builds

.github/actions/prepare-cross/action.yml

@@ -0,0 +1,60 @@
+name: Prepare cross builds
+description: Fetch portable Cargo sources and prepare the Linux cross tool once.
+outputs:
+  version:
+    description: CLI package version
+    value: ${{ steps.version.outputs.version }}
+  prerelease:
+    description: Whether the CLI version is a prerelease
+    value: ${{ steps.version.outputs.prerelease }}
+runs:
+  using: composite
+  steps:
+    - name: Install Rust
+      id: rust
+      uses: dtolnay/rust-toolchain@stable
+    # Only source downloads are portable across operating systems. This job is
+    # their sole cache writer; the build matrix only restores them.
+    - name: Cache cargo sources
+      id: sources
+      uses: actions/cache@v6.1.0
+      with:
+        path: |
+          ~/.cargo/registry
+          ~/.cargo/git/db
+        key: cross-sources-v1-${{ hashFiles('Cargo.lock') }}
+    - name: Fetch dependencies once for all targets
+      if: steps.sources.outputs.cache-hit != 'true'
+      shell: bash
+      run: cargo fetch --locked
+    - name: Read release version
+      id: version
+      shell: bash
+      run: |
+        version=$(cargo metadata --locked --no-deps --format-version 1 | jq -r '.packages[] | select(.name == "zoo") | .version')
+        echo "version=$version" >> "$GITHUB_OUTPUT"
+        if [[ "$version" == *rc* || "$version" == *pre* ]]; then
+          echo "prerelease=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "prerelease=false" >> "$GITHUB_OUTPUT"
+        fi
+    - name: Cache Linux cross tool
+      id: tools
+      uses: actions/cache@v6.1.0
+      with:
+        path: ~/.cargo/bin/cross
+        # Keep this cache key, the install version below, and cross-deps.sh in sync.
+        key: cross-tool-v1-${{ runner.os }}-${{ runner.arch }}-${{ steps.rust.outputs.cachekey }}-0.2.5
+    - name: Install cross once for Linux builds
+      if: steps.tools.outputs.cache-hit != 'true'
+      shell: bash
+      run: cargo install --locked cross --version 0.2.5
+    # Artifacts guarantee delivery within this run even if the cache is full
+    # or evicted. Only Linux runners consume this host executable.
+    - name: Share Linux cross tool
+      uses: actions/upload-artifact@v7
+      with:
+        name: cross-tool-Linux-X64
+        path: ~/.cargo/bin/cross
+        if-no-files-found: error
+        retention-days: 1

.github/workflows/cross-deps.sh

@@ -23,13 +23,13 @@ sudo apt update -y && sudo apt install -y \
 	zlib1g-dev
 
 # CI prepares the Cargo tools once before fanning out to target builds.
-# Keep installing them by default for local builds and the release workflow.
+# Keep installing them by default for local builds.
 if [[ "${1:-}" != "--system-only" ]]; then
 	# We need this for the version.
 	cargo install toml-cli --locked
 
 	# Install cross.
 	# Keep this version in sync with the cross install command and cache key
-	# in make-cross.yml.
+	# in .github/actions/prepare-cross/action.yml.
 	cargo install cross@0.2.5 --locked
 fi

.github/workflows/make-cross.yml

@@ -7,6 +7,7 @@ on:
       - Cargo.toml
       - Cargo.lock
       - .github/workflows/make-cross.yml
+      - .github/actions/prepare-cross/action.yml
       - .github/workflows/cross-deps.sh
       - Makefile
       - scripts/release-install-instructions.sh
@@ -22,49 +23,12 @@ jobs:
     name: Prepare cross builds
     runs-on: ubuntu-latest
     outputs:
-      version: ${{ steps.version.outputs.version }}
+      version: ${{ steps.prepare.outputs.version }}
     steps:
       - uses: actions/checkout@v7.0.1
-      - name: Install Rust
-        id: rust
-        uses: dtolnay/rust-toolchain@stable
-      # Only source downloads are portable across operating systems. This job is
-      # their sole cache writer; the build matrix only restores them.
-      - name: Cache cargo sources
-        id: sources
-        uses: actions/cache@v6.1.0
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git/db
-          key: cross-sources-v1-${{ hashFiles('Cargo.lock') }}
-      - name: Fetch dependencies once for all targets
-        if: steps.sources.outputs.cache-hit != 'true'
-        run: cargo fetch --locked
-      - name: Read release version
-        id: version
-        run: |
-          version=$(cargo metadata --locked --no-deps --format-version 1 | jq -r '.packages[] | select(.name == "zoo") | .version')
-          echo "version=$version" >> "$GITHUB_OUTPUT"
-      - name: Cache Linux cross tool
-        id: tools
-        uses: actions/cache@v6.1.0
-        with:
-          path: ~/.cargo/bin/cross
-          # Keep this cache key, the install version below, and cross-deps.sh in sync.
-          key: cross-tool-v1-${{ runner.os }}-${{ runner.arch }}-${{ steps.rust.outputs.cachekey }}-0.2.5
-      - name: Install cross once for Linux builds
-        if: steps.tools.outputs.cache-hit != 'true'
-        run: cargo install --locked cross --version 0.2.5
-      # Artifacts guarantee delivery within this run even if the cache is full
-      # or evicted. Only Linux runners consume this host executable.
-      - name: Share Linux cross tool
-        uses: actions/upload-artifact@v7
-        with:
-          name: cross-tool-Linux-X64
-          path: ~/.cargo/bin/cross
-          if-no-files-found: error
-          retention-days: 1
+      - name: Prepare sources and tools
+        id: prepare
+        uses: ./.github/actions/prepare-cross
   cross:
     needs: prepare
     strategy: