fix errcheck failed issue for the files of e2e-test, demos and tools. (…

…#9769)

* fix issue for examples/demo/server
* fix errcheck issue for testbed and tracegen
* fix govet error declaration of 'err' shadows declaration
Signed-off-by: Ziqi Zhao <zhaoziqi9146@gmail.com>

examples/demo/server/main.go

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 // Sample contains a simple http server that exports to the OpenTelemetry agent.
-// nolint:errcheck
+
 package main
 
 import (
@@ -141,6 +141,7 @@ func main() {
 	handler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
 		//  random sleep to simulate latency
 		var sleep int64
+
 		switch modulus := time.Now().Unix() % 5; modulus {
 		case 0:
 			sleep = rng.Int63n(2000)
@@ -166,12 +167,18 @@ func main() {
 		}
 		span.SetAttributes(baggageAttributes...)
 
-		w.Write([]byte("Hello World"))
+		if _, err := w.Write([]byte("Hello World")); err != nil {
+			http.Error(w, "write operation failed.", http.StatusInternalServerError)
+			return
+		}
+
 	})
 	wrappedHandler := otelhttp.NewHandler(handler, "/hello")
 
 	// serve up the wrapped handler
 	http.Handle("/hello", wrappedHandler)
-	http.ListenAndServe(":7080", nil)
+	if err := http.ListenAndServe(":7080", nil); err != nil {
+		handleErr(err, "server failed to serve")
+	}
 
 }

testbed/datareceivers/mockawsxraydatareceiver.go

@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// nolint:errcheck
 package datareceivers // import "github.com/open-telemetry/opentelemetry-collector-contrib/testbed/datareceivers"
 
 import (
@@ -81,8 +80,7 @@ func (ar *MockAwsXrayDataReceiver) Start(tc consumer.Traces, _ consumer.Metrics,
 }
 
 func (ar *MockAwsXrayDataReceiver) Stop() error {
-	ar.receiver.Shutdown(context.Background())
-	return nil
+	return ar.receiver.Shutdown(context.Background())
 }
 
 func (ar *MockAwsXrayDataReceiver) GenConfigYAMLStr() string {

testbed/mockdatareceivers/mockawsxrayreceiver/trace_receiver.go

@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// nolint:errcheck
 package mockawsxrayreceiver // import "github.com/open-telemetry/opentelemetry-collector-contrib/testbed/mockdatareceivers/mockawsxrayreceiver"
 
 import (
@@ -108,7 +107,9 @@ func (ar *MockAwsXrayReceiver) handleRequest(req *http.Request) error {
 
 	var result map[string]interface{}
 
-	json.Unmarshal(body, &result)
+	if err = json.Unmarshal(body, &result); err != nil {
+		log.Fatalln(err)
+	}
 
 	traces, _ := ToTraces(body)
 	sc := traces.SpanCount()

tracegen/internal/tracegen/worker.go

@@ -13,7 +13,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// nolint:errcheck
 package tracegen // import "github.com/open-telemetry/opentelemetry-collector-contrib/tracegen/internal/tracegen"
 
 import (
@@ -74,7 +73,9 @@ func (w worker) simulateTraces() {
 			semconv.PeerServiceKey.String("tracegen-client"),
 		))
 
-		limiter.Wait(context.Background())
+		if err := limiter.Wait(context.Background()); err != nil {
+			w.logger.Fatal("limiter waited failed, retry", zap.Error(err))
+		}
 
 		opt := trace.WithTimestamp(time.Now().Add(fakeSpanDuration))
 		child.End(opt)

tracegen/main.go

@@ -13,7 +13,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// nolint:errcheck
 package main
 
 import (
@@ -93,7 +92,13 @@ func main() {
 	}()
 
 	ssp := sdktrace.NewBatchSpanProcessor(exp, sdktrace.WithBatchTimeout(time.Second))
-	defer ssp.Shutdown(context.Background())
+	defer func() {
+		logger.Info("stop the batch span processor")
+		if err := ssp.Shutdown(context.Background()); err != nil {
+			logger.Error("failed to stop the batch span processor", zap.Error(err))
+			return
+		}
+	}()
 
 	tracerProvider := sdktrace.NewTracerProvider(
 		sdktrace.WithResource(resource.NewWithAttributes(semconv.SchemaURL, semconv.ServiceNameKey.String(cfg.ServiceName))),