ci: Cache gnd binaries to skip builds when source is unchanged

Cache the final compressed artifacts keyed on a hash of Cargo.lock,
all Cargo.toml files, and all .rs files. On cache hit, the entire
build pipeline (toolchain, dependencies, compilation, signing,
notarization, packaging) is skipped.

Author: lutter

.github/workflows/gnd-binary-build.yml

@@ -36,19 +36,30 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v6
 
+      - name: Cache built binary
+        id: bin-cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            ${{ matrix.asset_name }}.gz
+            ${{ matrix.asset_name }}.zip
+          key: gnd-${{ matrix.target }}-${{ hashFiles('Cargo.lock', '**/Cargo.toml', '**/*.rs') }}
+
       - name: Install Rust toolchain
+        if: steps.bin-cache.outputs.cache-hit != 'true'
         run: |
           rustup toolchain install stable
           rustup target add ${{ matrix.target }}
           rustup default stable
 
       - name: Rust Cache
+        if: steps.bin-cache.outputs.cache-hit != 'true'
         uses: Swatinem/rust-cache@v2
         with:
           key: ${{ matrix.target }}
 
       - name: Install dependencies (Ubuntu)
-        if: startsWith(matrix.runner, 'ubuntu')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'ubuntu')
         run: |
           sudo apt-get update
           sudo apt-get install -y protobuf-compiler musl-tools
@@ -57,27 +68,26 @@ jobs:
           fi
 
       - name: Install dependencies (macOS)
-        if: startsWith(matrix.runner, 'macos')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'macos')
         run: |
           brew install protobuf
 
       - name: Install protobuf (Windows)
-        if: startsWith(matrix.runner, 'windows')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'windows')
         run: choco install protoc
 
-
       - name: Build gnd binary (Unix/Mac)
-        if: ${{ !startsWith(matrix.runner, 'windows') }}
+        if: steps.bin-cache.outputs.cache-hit != 'true' && !startsWith(matrix.runner, 'windows')
         run: cargo build --bin gnd --release --target ${{ matrix.target }}
         env:
           CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: aarch64-linux-gnu-gcc
 
       - name: Build gnd binary (Windows)
-        if: startsWith(matrix.runner, 'windows')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'windows')
         run: cargo build --bin gnd --release --target ${{ matrix.target }}
 
       - name: Sign macOS binary
-        if: startsWith(matrix.runner, 'macos')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'macos')
         uses: lando/code-sign-action@v3
         with:
           file: target/${{ matrix.target }}/release/gnd
@@ -87,7 +97,7 @@ jobs:
           options: --options runtime --entitlements entitlements.plist
 
       - name: Notarize macOS binary
-        if: startsWith(matrix.runner, 'macos')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'macos')
         uses: lando/notarize-action@v2
         with:
           product-path: target/${{ matrix.target }}/release/gnd
@@ -96,14 +106,14 @@ jobs:
           appstore-connect-team-id: ${{ secrets.APPLE_TEAM_ID }}
 
       - name: Prepare binary (Unix)
-        if: ${{ !startsWith(matrix.runner, 'windows') }}
+        if: steps.bin-cache.outputs.cache-hit != 'true' && !startsWith(matrix.runner, 'windows')
         run: |
           cp target/${{ matrix.target }}/release/gnd ${{ matrix.asset_name }}
           chmod +x ${{ matrix.asset_name }}
           gzip ${{ matrix.asset_name }}
 
       - name: Prepare binary (Windows)
-        if: startsWith(matrix.runner, 'windows')
+        if: steps.bin-cache.outputs.cache-hit != 'true' && startsWith(matrix.runner, 'windows')
         run: |
           copy target\${{ matrix.target }}\release\gnd.exe ${{ matrix.asset_name }}
           7z a -tzip ${{ matrix.asset_name }}.zip ${{ matrix.asset_name }}