Add a kubelet /runningpods endpoint

/runningpods returns a list of pods currently running on the kubelet. The list
is composed by examining the container runtime, and may be different from the
desired pods to run known by kubelet.

This is useful for tests to verify that pods are indeed deleted on nodes.

pkg/kubelet/container/runtime.go

@@ -284,6 +284,24 @@ func (p *Pod) FindContainerByName(containerName string) *Container {
 	return nil
 }
 
+// ToAPIPod converts Pod to api.Pod. Note that if a field in api.Pod has no
+// corresponding field in Pod, the field would not be populated.
+func (p *Pod) ToAPIPod() *api.Pod {
+	var pod api.Pod
+	pod.UID = p.ID
+	pod.Name = p.Name
+	pod.Namespace = p.Namespace
+	pod.Status = p.Status
+
+	for _, c := range p.Containers {
+		var container api.Container
+		container.Name = c.Name
+		container.Image = c.Image
+		pod.Spec.Containers = append(pod.Spec.Containers, container)
+	}
+	return &pod
+}
+
 // IsEmpty returns true if the pod is empty.
 func (p *Pod) IsEmpty() bool {
 	return reflect.DeepEqual(p, &Pod{})