Do not schedule pod to the node under PID pressure.

Signed-off-by: Da K. Ma <klaus1982.cn@gmail.com>

test/integration/scheduler/predicates_test.go

@@ -870,3 +870,53 @@ func TestInterPodAffinity(t *testing.T) {
 		}
 	}
 }
+
+// TestNodePIDPressure verifies that scheduler's CheckNodePIDPressurePredicate predicate
+// functions works correctly.
+func TestNodePIDPressure(t *testing.T) {
+	context := initTest(t, "node-pid-pressure")
+	defer cleanupTest(t, context)
+	// Add a node.
+	node, err := createNode(context.clientSet, "testnode", nil)
+	if err != nil {
+		t.Fatalf("Cannot create node: %v", err)
+	}
+
+	cs := context.clientSet
+
+	// Adds PID pressure condition to the node.
+	node.Status.Conditions = []v1.NodeCondition{
+		{
+			Type:   v1.NodePIDPressure,
+			Status: v1.ConditionTrue,
+		},
+	}
+
+	// Update node condition.
+	err = updateNodeStatus(context.clientSet, node)
+	if err != nil {
+		t.Fatalf("Cannot update node: %v", err)
+	}
+
+	// Creats test pod.
+	testPod := &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{Name: "pidpressure-fake-name"},
+		Spec: v1.PodSpec{
+			Containers: []v1.Container{
+				{Name: "container", Image: imageutils.GetPauseImageName()},
+			},
+		},
+	}
+
+	testPod, err = cs.CoreV1().Pods(context.ns.Name).Create(testPod)
+	if err != nil {
+		t.Fatalf("Test Failed: error: %v, while creating pod", err)
+	}
+
+	err = waitForPodUnschedulable(cs, testPod)
+	if err != nil {
+		t.Errorf("Test Failed: error, %v, while waiting for scheduled", err)
+	}
+
+	cleanupPods(cs, t, []*v1.Pod{testPod})
+}