fix(daemon): enable go vet check on pull requests (#1005)

Address issues spotted by `go vet`:
- fix syntax of `kubernetes.KubernetesServiceHost` struct tags
- ensure `context.cancel()` is always called to avoid context leak

Add go vet check for pull requests.

Author: lavarou

.github/workflows/test-agent.yml

@@ -44,6 +44,39 @@ jobs:
             echo "$GOFMT_REPORTED_FILES" >> $GITHUB_STEP_SUMMARY
             exit 1
           fi
+  govet:
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+      - name: Checkout newrelic-php-agent code
+        uses: actions/checkout@v4
+        with:
+          path: php-agent
+      - name: Get go version
+        id: get-go-version
+        run: |
+          echo "go toolchain version required to build the daemon:"
+          toolchain="$(awk '/^toolchain */ {gsub(/^go/, "", $2); print $2}' ./php-agent/daemon/go.mod)"
+          echo "[${toolchain}]"
+          echo "go-toolchain-version=${toolchain}" >> $GITHUB_OUTPUT
+      - name: Setup go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ steps.get-go-version.outputs.go-toolchain-version }}
+          cache-dependency-path: "**/*.sum"
+      - name: Verify go version
+        run: |
+          echo "Verify correct go toolchain version is used"
+          actual="$(go version)"
+          echo "Actual: [$actual]"
+          expected="go version go${{ steps.get-go-version.outputs.go-toolchain-version }} linux/amd64"
+          echo "Expected: [$expected]"
+          if [ "$actual" != "$expected" ]; then
+            exit 1
+          fi
+      - name: Run go vet
+        run: go vet -C ./php-agent/daemon ./...
+        shell: bash
   daemon-unit-tests:
     runs-on: ubuntu-latest
     env:

daemon/cmd/daemon/worker.go

@@ -124,6 +124,7 @@ func runWorker(cfg *Config) {
 	hasProgenitor := !(cfg.Foreground || cfg.WatchdogForeground)
 
 	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel() // Ensure that the context is always cancelled when the worker exits, not only when signal is caught.
 
 	select {
 	case <-listenAndServe(ctx, cfg.BindAddr, errorChan, p, hasProgenitor):
@@ -140,7 +141,8 @@ func runWorker(cfg *Config) {
 	case caught := <-signalChan:
 		// Close the listener before sending remaining data. This ensures that the socket
 		// connection is closed as soon as possible and other processes can start listening
-		// the socket while remaining data is sent.
+		// the socket while remaining data is sent. Earlier defer cancel() will be a no-op
+		// because cancel() is called here explicitly.
 		cancel()
 		log.Infof("worker received signal %d - sending remaining data", caught)
 		p.CleanExit()

daemon/internal/newrelic/utilization/kubernetes.go

@@ -11,7 +11,7 @@ import (
 )
 
 type kubernetes struct {
-	KubernetesServiceHost string `json:"kubernetes_service_host",omitempty`
+	KubernetesServiceHost string `json:"kubernetes_service_host,omitempty"`
 
 	// Having a custom getter allows the unit tests to mock os.Getenv().
 	environmentVariableGetter func(key string) string