feat(dashboard): better error handling in dashboard code

fixes kubeflow#335

dashboard/backend/handler/api_handler.go

@@ -6,13 +6,16 @@ import (
 	"fmt"
 	"net/http"
 
-	restful "github.com/emicklei/go-restful"
+	log "github.com/golang/glog"
+
+	"github.com/emicklei/go-restful"
 	"github.com/tensorflow/k8s/dashboard/backend/client"
 	"github.com/tensorflow/k8s/pkg/apis/tensorflow/v1alpha1"
 
 	"k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
+	"k8s.io/apimachinery/pkg/api/errors"
 )
 
 // APIHandler handles the API calls
@@ -88,24 +91,30 @@ func CreateHTTPAPIHandler(client client.ClientManager) (http.Handler, error) {
 }
 
 func (apiHandler *APIHandler) handleGetTfJobs(request *restful.Request, response *restful.Response) {
-
 	//TODO: namespace handling
-	jobs, err := apiHandler.cManager.TfJobClient.TensorflowV1alpha1().TfJobs("default").List(metav1.ListOptions{})
-
+	namespace := "default"
+	jobs, err := apiHandler.cManager.TfJobClient.TensorflowV1alpha1().TfJobs(namespace).List(metav1.ListOptions{})
 	if err != nil {
-		panic(err)
+		log.Warningf("failed to list TfJobs under namespace %v: %v", namespace, err)
+		response.WriteError(http.StatusInternalServerError, err)
+	} else {
+		log.Infof("successfully listed TfJobs under namespace %v", namespace)
+		response.WriteHeaderAndEntity(http.StatusOK, jobs)
 	}
-
-	response.WriteHeaderAndEntity(http.StatusOK, jobs)
 }
 
 func (apiHandler *APIHandler) handleGetTfJobDetail(request *restful.Request, response *restful.Response) {
 	namespace := request.PathParameter("namespace")
 	name := request.PathParameter("tfjob")
-
 	job, err := apiHandler.cManager.TfJobClient.TensorflowV1alpha1().TfJobs(namespace).Get(name, metav1.GetOptions{})
 	if err != nil {
-		panic(err)
+		log.Infof("cannot find TfJob %v under namespace %v, error: %v", name, namespace, err)
+		if errors.IsNotFound(err) {
+			response.WriteError(http.StatusNotFound, err)
+		} else {
+			response.WriteError(http.StatusInternalServerError, err)
+		}
+		return
 	}
 
 	tfJobDetail := TfJobDetail{
@@ -117,15 +126,18 @@ func (apiHandler *APIHandler) handleGetTfJobDetail(request *restful.Request, res
 			LabelSelector: fmt.Sprintf("tensorflow.org=,app=tensorboard,runtime_id=%s", job.Spec.RuntimeId),
 		})
 		if err != nil {
-			panic(err)
-		}
-
-		if len(tbSpec.Items) > 0 {
+			log.Warningf("failed to list TensorBoard for TfJob %v under namespace %v, error: %v", job.Name, job.Namespace, err)
+			// TODO maybe partial result?
+			response.WriteError(http.StatusNotFound, err)
+			return
+		} else if len(tbSpec.Items) > 0 {
 			// Should never be more than 1 service that matched, handle error
-			// Handle case where no tensorboard is found
+			// Handle case where no TensorBoard is found
 			tfJobDetail.TbService = &tbSpec.Items[0]
+			log.Warningf("more than one TensorBoards found for TfJob %v under namespace %v, this should be impossible",
+				job.Name, job.Namespace)
 		} else {
-			fmt.Println(fmt.Sprintf("Couldn't find a TensorBoard service for TfJob %s", job.Name))
+			log.Warningf("Couldn't find a TensorBoard service for TfJob %v under namespace %v", job.Name, job.Namespace)
 		}
 	}
 
@@ -134,45 +146,55 @@ func (apiHandler *APIHandler) handleGetTfJobDetail(request *restful.Request, res
 		LabelSelector: fmt.Sprintf("tensorflow.org=,runtime_id=%s", job.Spec.RuntimeId),
 	})
 	if err != nil {
-		panic(err)
+		log.Warningf("failed to list pods for TfJob %v under namespace %v: %v", name, namespace, err)
+		response.WriteError(http.StatusInternalServerError, err)
+	} else {
+		log.Infof("successfully listed pods for TfJob %v under namespace %v", name, namespace)
+		tfJobDetail.Pods = pods.Items
+		response.WriteHeaderAndEntity(http.StatusOK, tfJobDetail)
 	}
-	tfJobDetail.Pods = pods.Items
-
-	response.WriteHeaderAndEntity(http.StatusOK, tfJobDetail)
 }
 
 func (apiHandler *APIHandler) handleDeploy(request *restful.Request, response *restful.Response) {
-	client := apiHandler.cManager.TfJobClient
+	clt := apiHandler.cManager.TfJobClient
 	tfJob := new(v1alpha1.TfJob)
 	if err := request.ReadEntity(tfJob); err != nil {
-		panic(err)
+		response.WriteError(http.StatusBadRequest, err)
+		return
 	}
-	j, err := client.TensorflowV1alpha1().TfJobs(tfJob.Namespace).Create(tfJob)
+	j, err := clt.TensorflowV1alpha1().TfJobs(tfJob.Namespace).Create(tfJob)
 	if err != nil {
-		panic(err)
+		log.Warningf("failed to deploy TfJob %v under namespace %v: %v", tfJob.Name, tfJob.Namespace, err)
+		response.WriteError(http.StatusInternalServerError, err)
+	} else {
+		log.Infof("successfully deployed TfJob %v under namespace %v", tfJob.Name, tfJob.Namespace)
+		response.WriteHeaderAndEntity(http.StatusCreated, j)
 	}
-	response.WriteHeaderAndEntity(http.StatusCreated, j)
 }
 
 func (apiHandler *APIHandler) handleDeleteTfJob(request *restful.Request, response *restful.Response) {
 	namespace := request.PathParameter("namespace")
 	name := request.PathParameter("tfjob")
-	client := apiHandler.cManager.TfJobClient
-	err := client.TensorflowV1alpha1().TfJobs(namespace).Delete(name, &metav1.DeleteOptions{})
+	clt := apiHandler.cManager.TfJobClient
+	err := clt.TensorflowV1alpha1().TfJobs(namespace).Delete(name, &metav1.DeleteOptions{})
 	if err != nil {
-		panic(err)
+		log.Warningf("failed to delete TfJob %v under namespace %v: %v", name, namespace, err)
+		response.WriteError(http.StatusInternalServerError, err)
+	} else {
+		log.Infof("successfully deleted TfJob %v under namespace %v", name, namespace)
+		response.WriteHeader(http.StatusNoContent)
 	}
-	response.WriteHeader(http.StatusOK)
 }
 
 func (apiHandler *APIHandler) handleGetPodLogs(request *restful.Request, response *restful.Response) {
 	namespace := request.PathParameter("namespace")
 	name := request.PathParameter("podname")
-
 	logs, err := apiHandler.cManager.ClientSet.CoreV1().Pods(namespace).GetLogs(name, &v1.PodLogOptions{}).Do().Raw()
 	if err != nil {
-		panic(err)
+		log.Warningf("failed to get pod logs for TfJob %v under namespace %v: %v", name, namespace, err)
+		response.WriteError(http.StatusInternalServerError, err)
+	} else {
+		log.Infof("successfully get pod logs for TfJob %v under namespace %v", name, namespace)
+		response.WriteHeaderAndEntity(http.StatusOK, string(logs))
 	}
-
-	response.WriteHeaderAndEntity(http.StatusOK, string(logs))
 }