Fix daemonset flapping when using a host port

pkg/controller/daemon/controller.go

@@ -601,6 +601,11 @@ func (dsc *DaemonSetsController) nodeShouldRunDaemonPod(node *api.Node, ds *exte
 		if pod.Spec.NodeName != node.Name {
 			continue
 		}
+		// ignore pods that belong to the daemonset when taking into account wheter
+		// a daemonset should bind to a node.
+		if pds := dsc.getPodDaemonSet(pod); pds != nil && ds.Name == pds.Name {
+			continue
+		}
 		pods = append(pods, pod)
 	}
 	_, notFittingCPU, notFittingMemory := predicates.CheckPodsExceedingFreeResources(pods, node.Status.Allocatable)

pkg/controller/daemon/controller_test.go

@@ -284,6 +284,36 @@ func TestPortConflictNodeDaemonDoesNotLaunchPod(t *testing.T) {
 	manager.podStore.Add(&api.Pod{
 		Spec: podSpec,
 	})
+
+	ds := newDaemonSet("foo")
+	ds.Spec.Template.Spec = podSpec
+	manager.dsStore.Add(ds)
+	syncAndValidateDaemonSets(t, manager, ds, podControl, 0, 0)
+}
+
+// Test that if the node is already scheduled with a pod using a host port
+// but belonging to the same daemonset, we don't delete that pod
+//
+// Issue: https://github.com/kubernetes/kubernetes/issues/22309
+func TestPortConflictWithSameDaemonPodDoesNotDeletePod(t *testing.T) {
+	podSpec := api.PodSpec{
+		NodeName: "port-conflict",
+		Containers: []api.Container{{
+			Ports: []api.ContainerPort{{
+				HostPort: 666,
+			}},
+		}},
+	}
+	manager, podControl := newTestController()
+	node := newNode("port-conflict", nil)
+	manager.nodeStore.Add(node)
+	manager.podStore.Add(&api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			Labels:    simpleDaemonSetLabel,
+			Namespace: api.NamespaceDefault,
+		},
+		Spec: podSpec,
+	})
 	ds := newDaemonSet("foo")
 	ds.Spec.Template.Spec = podSpec
 	manager.dsStore.Add(ds)