List containers when given container is not found

staging/src/k8s.io/kubectl/pkg/cmd/exec/exec.go

@@ -358,6 +358,11 @@ func (p *ExecOptions) Run() error {
 			return err
 		}
 		containerName = container.Name
+	} else {
+		container, _ := podcmd.FindContainerByName(pod, p.ContainerName)
+		if container == nil {
+			return fmt.Errorf("container %s is not valid for pod %s out of: %s", p.ContainerName, pod.Name, podcmd.AllContainerNames(pod))
+		}
 	}
 
 	// ensure we can recover the terminal while attached

staging/src/k8s.io/kubectl/pkg/polymorphichelpers/logsforobject.go

@@ -116,7 +116,7 @@ func logsForObjectWithClient(clientset corev1client.CoreV1Interface, object, opt
 
 			container, fieldPath := podcmd.FindContainerByName(t, currOpts.Container)
 			if container == nil {
-				return nil, fmt.Errorf("container %s is not valid for pod %s", currOpts.Container, t.Name)
+				return nil, fmt.Errorf("container %s is not valid for pod %s out of: %s", currOpts.Container, t.Name, podcmd.AllContainerNames(t))
 			}
 			ref, err := reference.GetPartialReference(scheme.Scheme, t, fieldPath)
 			if err != nil {

staging/src/k8s.io/kubectl/pkg/polymorphichelpers/logsforobject_test.go

@@ -384,6 +384,12 @@ func TestLogsForObject(t *testing.T) {
 				FieldPath:  fmt.Sprintf("spec.containers{%s}", testPodWithOneContainers().Spec.Containers[0].Name),
 			}},
 		},
+		{
+			name:        "pod logs: invalid container name",
+			obj:         testPodWithTwoContainers(),
+			opts:        &corev1.PodLogOptions{Container: "nonexistent"},
+			expectedErr: "container nonexistent is not valid for pod foo-two-containers out of: foo-2-c1, foo-2-c2",
+		},
 	}
 
 	for _, test := range tests {

test/cmd/exec.sh

@@ -63,6 +63,10 @@ __EOF__
   # These must be pass the validate
   kube::test::if_has_not_string "${output_message}" 'pod or type/name must be specified'
 
+  ### Test execute with invalid container name
+  output_message=$(! kubectl exec test-pod -c nonexistent -- date 2>&1)
+  kube::test::if_has_string "${output_message}" 'container nonexistent is not valid for pod test-pod out of: kubernetes-pause'
+
   # Clean up
   kubectl delete pods test-pod