Print more details when network diagnostics test setup fails

Currently when network diags fails, it only informs how many test pods
failed but doesn't provide why those pods failed. This change will fetch
logs for the pods in case of setup failure.

pkg/diagnostics/network/setup.go

@@ -10,6 +10,7 @@ import (
 	kerrs "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	kerrors "k8s.io/apimachinery/pkg/util/errors"
+	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/storage/names"
 	kclientcmd "k8s.io/client-go/tools/clientcmd"
@@ -66,7 +67,12 @@ func (d *NetworkDiagnostic) TestSetup() error {
 	}
 	// Wait for test pods and services to be up and running on all valid nodes
 	if err = d.waitForTestPodAndService(nsList); err != nil {
-		return fmt.Errorf("Failed to run network diags test pod and service: %v", err)
+		logData, er := d.getPodLogs(nsList)
+		if er != nil {
+			return fmt.Errorf("Failed to run network diags test pod and service: %v, fetching logs failed: %v", err, er)
+		} else {
+			return fmt.Errorf("Failed to run network diags test pod and service: %v, details: %s", err, logData)
+		}
 	}
 	return nil
 }
@@ -169,6 +175,41 @@ func (d *NetworkDiagnostic) waitForTestPodAndService(nsList []string) error {
 	return kerrors.NewAggregate(errList)
 }
 
+func (d *NetworkDiagnostic) getPodLogs(nsList []string) (string, error) {
+	logData := sets.String{}
+	errList := []error{}
+	limit := int64(1024)
+
+	for _, name := range nsList {
+		podList, err := d.getPodList(name, util.NetworkDiagTestPodNamePrefix)
+		if err != nil {
+			return "", err
+		}
+
+		for _, pod := range podList.Items {
+			opts := &kapi.PodLogOptions{
+				TypeMeta:   pod.TypeMeta,
+				Container:  pod.Name,
+				Follow:     true,
+				LimitBytes: &limit,
+			}
+
+			req, err := d.Factory.LogsForObject(&pod, opts, 10*time.Second)
+			if err != nil {
+				errList = append(errList, err)
+				continue
+			}
+			data, err := req.DoRaw()
+			if err != nil {
+				errList = append(errList, err)
+				continue
+			}
+			logData.Insert(string(data[:]))
+		}
+	}
+	return strings.Join(logData.List(), ", "), kerrors.NewAggregate(errList)
+}
+
 func (d *NetworkDiagnostic) getCountOfTestPods(nsList []string) (int, int, error) {
 	totalPodCount := 0
 	runningPodCount := 0