ci: switch to sccache for Rust compilation cache

Author: sandhose

.github/workflows/build.yaml

@@ -21,6 +21,8 @@ concurrency:
 env:
   CARGO_TERM_COLOR: always
   CARGO_NET_GIT_FETCH_WITH_CLI: "true"
+  SCCACHE_GHA_ENABLED: "true"
+  RUSTC_WRAPPER: "sccache"
   IMAGE: ghcr.io/matrix-org/matrix-authentication-service
   IMAGE_SYN2MAS: ghcr.io/matrix-org/matrix-authentication-service/syn2mas
   BUILDCACHE: ghcr.io/matrix-org/matrix-authentication-service/buildcache
@@ -54,10 +56,8 @@ jobs:
             x86_64-apple-darwin
             aarch64-apple-darwin
 
-      - name: Setup Rust build cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Install zig
         uses: goto-bus-stop/setup-zig@v2

.github/workflows/ci.yaml

@@ -15,6 +15,8 @@ concurrency:
 env:
   CARGO_TERM_COLOR: always
   CARGO_NET_GIT_FETCH_WITH_CLI: "true"
+  SCCACHE_GHA_ENABLED: "true"
+  RUSTC_WRAPPER: "sccache"
 
 jobs:
   opa-lint:
@@ -116,6 +118,10 @@ jobs:
     name: Run `cargo deny` checks
     runs-on: ubuntu-latest
 
+    env:
+      # We need to remove the sccache wrapper because we don't install it in this job
+      RUSTC_WRAPPER: ""
+
     permissions:
       contents: read
 
@@ -143,10 +149,8 @@ jobs:
           rustup toolchain install stable
           rustup default stable
 
-      - name: Setup Rust cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Install Node
         uses: actions/[email protected]
@@ -204,10 +208,8 @@ jobs:
         working-directory: ./policies
         run: make
 
-      - name: Setup Rust cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Run clippy
         run: |
@@ -268,10 +270,8 @@ jobs:
         working-directory: ./policies
         run: make
 
-      - name: Setup Rust cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Test
         id: test

.github/workflows/coverage.yaml

@@ -78,6 +78,10 @@ jobs:
     permissions:
       contents: read
 
+    env:
+      SCCACHE_GHA_ENABLED: "true"
+      RUSTC_WRAPPER: "sccache"
+
     services:
       postgres:
         image: docker.io/library/postgres:15.3
@@ -125,10 +129,8 @@ jobs:
         working-directory: ./policies
         run: make
 
-      - name: Setup Rust cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Download grcov
         run: |

.github/workflows/docs.yaml

@@ -27,10 +27,8 @@ jobs:
           rustup toolchain install stable
           rustup default stable
 
-      - name: Setup Rust cache
-        uses: Swatinem/[email protected]
-        with:
-          save-if: "${{ github.event_name != 'pull_request' }}"
+      - name: Setup sccache
+        uses: mozilla-actions/[email protected]
 
       - name: Setup mdBook
         uses: peaceiris/[email protected]