Cache rustup+registry+target, reach cache server via LAN IP, fail on pipe errors

.gitea/workflows/sandbox.yml

@@ -10,30 +10,37 @@ jobs:
     defaults:
       run:
         working-directory: sandbox
+        shell: bash
     steps:
       - uses: actions/checkout@v4
 
       - name: Where am I?
         run: |
           echo "runner : ${RUNNER_NAME}"
-          echo "os     : $(grep PRETTY_NAME /etc/os-release | cut -d'"' -f2)"
-          echo "uid    : $(id -u)  cgroup: $(head -c 40 /proc/self/cgroup)"
-          command -v git >/dev/null && echo "git    : $(git --version)"
+          echo "uid    : $(id -u)   cgroup: $(cut -d/ -f3 /proc/self/cgroup 2>/dev/null || echo n/a)"
+          echo "cache  : ${ACTIONS_CACHE_URL:-unset}"
 
-      - name: Toolchain
-        run: |
-          command -v cargo >/dev/null || { apt-get update -qq && apt-get install -y -qq --no-install-recommends rustc cargo >/dev/null; }
-          cargo --version
-
-      - name: Cache cargo deps and target
+      # Restore first, so a warm cache also skips the toolchain download.
+      - name: Cache rust toolchain, registry and target
         uses: actions/cache@v4
         with:
           path: |
-            ~/.cargo/registry
-            ~/.cargo/git
+            ~/.cargo
+            ~/.rustup
             sandbox/target
           key: cargo-${{ hashFiles('sandbox/Cargo.lock') }}
           restore-keys: cargo-
 
+      - name: Toolchain
+        run: |
+          set -euo pipefail
+          if ! command -v cargo >/dev/null && [ ! -x "$HOME/.cargo/bin/cargo" ]; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal --default-toolchain stable
+          fi
+          echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+          cargo --version
+
       - name: Test
-        run: cargo test 2>&1 | tail -6
+        run: |
+          set -o pipefail          # without this a failing build looks green
+          cargo test 2>&1 | tail -4