ci: setup sccache (#3403)

.github/workflows/ci.yml

@@ -28,8 +28,8 @@ env:
   RUSTFLAGS: "-D warnings"
 
 jobs:
-  cache: # Warm cache factory for all other CI jobs
-    name: Check and Build
+  test:
+    name: Test
     strategy:
       fail-fast: false
       matrix:
@@ -38,21 +38,29 @@ jobs:
           - os: ubuntu-latest
           - os: macos-14
     runs-on: ${{ matrix.os }}
+    env:
+      # https://github.com/mozilla/sccache/blob/main/docs/S3.md
+      AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+      AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+      SCCACHE_BUCKET: ${{ secrets.SCCACHE_BUCKET }}
+      SCCACHE_ENDPOINT: ${{ secrets.SCCACHE_ENDPOINT }}
+      SCCACHE_REGION: auto
+      RUSTC_WRAPPER: sccache
+      CARGO_INCREMENTAL: 0
+      SCCACHE_LOCAL_RW_MODE:
     steps:
       - uses: taiki-e/checkout-action@v1
-
-      - name: Install Rust Toolchain
-        uses: ./.github/actions/rustup
+      - uses: ./.github/actions/rustup
         with:
+          # warm cache factory for all other CI jobs
+          # cache `target` directory to avoid download crates
           save-cache: ${{ github.ref_name == 'main' }}
-
-      - name: Cargo check
-        run: cargo ck
-
-      # Only need to build the test to create a warm cache on the main branch
-      - name: Build cache by Cargo Check and Cargo Test
-        if: ${{ github.ref_name == 'main' }}
-        run: cargo test --quiet --no-run
+      # cache build outputs to speed up compilation
+      - uses: mozilla-actions/sccache-action@v0.0.4
+        if: ${{ vars.USE_SCCACHE == 'true' }}
+      - run: cargo ck
+      - run: cargo test --no-run
+      - run: cargo test
 
   wasm:
     name: Check Wasm
@@ -186,25 +194,18 @@ jobs:
       - name: Run doc
         run: RUSTDOCFLAGS='-D warnings' cargo doc --no-deps --document-private-items
 
-  test:
-    name: Test
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - os: windows-latest
-          - os: ubuntu-latest
-          - os: macos-14
-    runs-on: ${{ matrix.os }}
-    steps:
-      - uses: taiki-e/checkout-action@v1
-      - name: Install Rust
-        uses: ./.github/actions/rustup
-      - run: cargo test --quiet
-
   conformance:
     name: Conformance
     runs-on: ubuntu-latest
+    env:
+      # https://github.com/mozilla/sccache/blob/main/docs/S3.md
+      AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+      AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+      SCCACHE_BUCKET: ${{ secrets.SCCACHE_BUCKET }}
+      SCCACHE_ENDPOINT: ${{ secrets.SCCACHE_ENDPOINT }}
+      SCCACHE_REGION: auto
+      RUSTC_WRAPPER: sccache
+      CARGO_INCREMENTAL: 0
     steps:
       - uses: taiki-e/checkout-action@v1
 
@@ -222,6 +223,8 @@ jobs:
           shared-key: 'conformance'
           save-cache: ${{ github.ref_name == 'main' }}
 
+      - uses: mozilla-actions/sccache-action@v0.0.4
+
       - name: Clone submodules
         if: steps.filter.outputs.src == 'true'
         uses: ./.github/actions/clone-submodules