ci: reuse compiled integration tests and prebuilt images

Updates #3542

(cherry picked from commit c9852c43da)

.github/workflows/integration-test-template.yml

@@ -61,10 +61,10 @@ jobs:
         with:
           name: hi-binary
           path: /tmp/artifacts
-      - name: Download Go cache
+      - name: Download integration test binary
         uses: actions/download-artifact@018cc2cf5baa6db3ef3c5f8a56943fffe632ef53 # v6.0.0
         with:
-          name: go-cache
+          name: integration-test-binary
           path: /tmp/artifacts
       - name: Download postgres image
         if: ${{ inputs.postgres_flag == '--postgres=1' }}
@@ -87,7 +87,7 @@ jobs:
         with:
           username: ${{ env.DOCKERHUB_USERNAME }}
           password: ${{ env.DOCKERHUB_TOKEN }}
-      - name: Load Docker images, Go cache, and prepare binary
+      - name: Load Docker images and prepare binaries
         run: |
           gunzip -c /tmp/artifacts/headscale-image.tar.gz | docker load
           gunzip -c /tmp/artifacts/tailscale-head-image.tar.gz | docker load
@@ -95,33 +95,30 @@ jobs:
           if [ -f /tmp/artifacts/postgres-image.tar.gz ]; then
             gunzip -c /tmp/artifacts/postgres-image.tar.gz | docker load
           fi
-          chmod +x /tmp/artifacts/hi
+          chmod +x /tmp/artifacts/hi /tmp/artifacts/integration.test
           docker images
-          # Extract Go cache to host directories for bind mounting
-          mkdir -p /tmp/go-cache
-          tar -xzf /tmp/artifacts/go-cache.tar.gz -C /tmp/go-cache
-          ls -la /tmp/go-cache/ /tmp/go-cache/.cache/
       - name: Run Integration Test
         env:
           HEADSCALE_INTEGRATION_HEADSCALE_IMAGE: headscale:${{ github.sha }}
           HEADSCALE_INTEGRATION_TAILSCALE_IMAGE: tailscale-head:${{ github.sha }}
           HEADSCALE_INTEGRATION_POSTGRES_IMAGE: ${{ inputs.postgres_flag == '--postgres=1' && format('postgres:{0}', github.sha) || '' }}
-          HEADSCALE_INTEGRATION_GO_CACHE: /tmp/go-cache/go
-          HEADSCALE_INTEGRATION_GO_BUILD_CACHE: /tmp/go-cache/.cache/go-build
           # Mirror the docker/login-action secrets into env so the
           # dockertestutil.Credentials resolver picks them up directly
           # (otherwise it falls back to parsing ~/.docker/config.json,
           # which works but is one step further from the source).
           DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_CI_USERNAME }}
           DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_CI_TOKEN }}
-        run: /tmp/artifacts/hi run --stats --ts-memory-limit=300 --hs-memory-limit=1500 "^${{ inputs.test }}$" \
-          --timeout=120m \
-          ${{ inputs.postgres_flag }}
+        run: |
+          /tmp/artifacts/hi run --stats --ts-memory-limit=300 --hs-memory-limit=1500 \
+            --test-binary=/tmp/artifacts/integration.test \
+            --timeout=120m \
+            ${{ inputs.postgres_flag }} \
+            "^${{ inputs.test }}$"
       # Sanitize test name for artifact upload (replace invalid characters: " : < > | * ? \ / with -)
       - name: Sanitize test name for artifacts
         if: always()
         id: sanitize
-        run: echo "name=${TEST_NAME//[\":<>|*?\\\/]/-}" >> $GITHUB_OUTPUT
+        run: echo "name=${TEST_NAME//[\":<>|*?\\\/]/-}" >> "$GITHUB_OUTPUT"
         env:
           TEST_NAME: ${{ inputs.test }}
       - uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0

.github/workflows/test-integration.yaml

@@ -43,15 +43,13 @@ jobs:
         with:
           primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
           restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}
-      - name: Build binaries and warm Go cache
+      - name: Build binaries
         if: steps.changed-files.outputs.files == 'true'
         run: |
-          # Build all Go binaries in one nix shell to maximize cache reuse
           nix develop --command -- bash -c '
             go build -o hi ./cmd/hi
             CGO_ENABLED=0 GOOS=linux go build -o headscale ./cmd/headscale
-            # Build integration test binary to warm the cache with all dependencies
-            go test -c ./integration -o /dev/null 2>/dev/null || true
+            CGO_ENABLED=0 GOOS=linux go test -c ./integration -o integration.test
           '
       - name: Upload hi binary
         if: steps.changed-files.outputs.files == 'true'
@@ -60,17 +58,12 @@ jobs:
           name: hi-binary
           path: hi
           retention-days: 10
-      - name: Package Go cache
-        if: steps.changed-files.outputs.files == 'true'
-        run: |
-          # Package Go module cache and build cache
-          tar -czf go-cache.tar.gz -C ~ go .cache/go-build
-      - name: Upload Go cache
+      - name: Upload integration test binary
         if: steps.changed-files.outputs.files == 'true'
         uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
         with:
-          name: go-cache
-          path: go-cache.tar.gz
+          name: integration-test-binary
+          path: integration.test
           retention-days: 10
       - name: Force overlay2 storage driver
         if: steps.changed-files.outputs.files == 'true'