From f6fb0bd308fff8810e46f2e52f617a73f9dbcfdd Mon Sep 17 00:00:00 2001
From: Aldo Culquicondor <acondor@google.com>
Date: Wed, 21 Oct 2020 18:06:03 -0400
Subject: [PATCH] Add integration test for Default PodTopologySpread

Simulating a cluster with 500 nodes in 3 zones, deploying 3, 12 and 27 Pods belonging to the same service.

Change-Id: I16425594012ea7bd24b888acedb12958360bff97
---
 test/integration/scheduler/priorities_test.go | 98 ++++++++++++++++++-
 1 file changed, 96 insertions(+), 2 deletions(-)

diff --git a/test/integration/scheduler/priorities_test.go b/test/integration/scheduler/priorities_test.go
index ea0f1311a84..de16a480413 100644
--- a/test/integration/scheduler/priorities_test.go
+++ b/test/integration/scheduler/priorities_test.go
@@ -25,6 +25,7 @@ import (
 	v1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/kubernetes/pkg/scheduler"
 	schedulerconfig "k8s.io/kubernetes/pkg/scheduler/apis/config"
@@ -254,8 +255,8 @@ func makeContainersWithImages(images []string) []v1.Container {
 	return containers
 }
 
-// TestEvenPodsSpreadPriority verifies that EvenPodsSpread priority functions well.
-func TestEvenPodsSpreadPriority(t *testing.T) {
+// TestPodTopologySpreadScore verifies that the PodTopologySpread Score plugin works.
+func TestPodTopologySpreadScore(t *testing.T) {
 	testCtx := initTestSchedulerForPriorityTest(t, podtopologyspread.Name)
 	defer testutils.CleanupTest(t, testCtx)
 	cs := testCtx.ClientSet
@@ -361,3 +362,96 @@ func TestEvenPodsSpreadPriority(t *testing.T) {
 		})
 	}
 }
+
+// TestDefaultPodTopologySpreadScore verifies that the PodTopologySpread Score plugin
+// with the system default spreading spreads Pods belonging to a Service.
+// The setup has 300 nodes over 3 zones.
+func TestDefaultPodTopologySpreadScore(t *testing.T) {
+	testCtx := initTestSchedulerForPriorityTest(t, podtopologyspread.Name)
+	t.Cleanup(func() {
+		testutils.CleanupTest(t, testCtx)
+	})
+	cs := testCtx.ClientSet
+	ns := testCtx.NS.Name
+
+	zoneForNode := make(map[string]string)
+	for i := 0; i < 300; i++ {
+		nodeName := fmt.Sprintf("node-%d", i)
+		zone := fmt.Sprintf("zone-%d", i%3)
+		zoneForNode[nodeName] = zone
+		_, err := createNode(cs, st.MakeNode().Name(nodeName).Label(v1.LabelHostname, nodeName).Label(v1.LabelZoneFailureDomainStable, zone).Obj())
+		if err != nil {
+			t.Fatalf("Cannot create node: %v", err)
+		}
+	}
+
+	serviceName := "test-service"
+	svc := &v1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      serviceName,
+			Namespace: ns,
+		},
+		Spec: v1.ServiceSpec{
+			Selector: map[string]string{
+				"service": serviceName,
+			},
+			Ports: []v1.ServicePort{{
+				Port:       80,
+				TargetPort: intstr.FromInt(80),
+			}},
+		},
+	}
+	_, err := cs.CoreV1().Services(ns).Create(testCtx.Ctx, svc, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("Cannot create Service: %v", err)
+	}
+
+	pause := imageutils.GetPauseImageName()
+	totalPodCnt := 0
+	for _, nPods := range []int{3, 9, 15} {
+		// Append nPods each iteration.
+		t.Run(fmt.Sprintf("%d-pods", totalPodCnt+nPods), func(t *testing.T) {
+			for i := 0; i < nPods; i++ {
+				p := st.MakePod().Name(fmt.Sprintf("p-%d", totalPodCnt)).Label("service", serviceName).Container(pause).Obj()
+				_, err = cs.CoreV1().Pods(ns).Create(testCtx.Ctx, p, metav1.CreateOptions{})
+				if err != nil {
+					t.Fatalf("Cannot create Pod: %v", err)
+				}
+				totalPodCnt++
+			}
+			var pods []v1.Pod
+			// Wait for all Pods scheduled.
+			err = wait.Poll(pollInterval, wait.ForeverTestTimeout, func() (bool, error) {
+				podList, err := cs.CoreV1().Pods(ns).List(testCtx.Ctx, metav1.ListOptions{})
+				if err != nil {
+					t.Fatalf("Cannot list pods to verify scheduling: %v", err)
+				}
+				for _, p := range podList.Items {
+					if p.Spec.NodeName == "" {
+						return false, nil
+					}
+				}
+				pods = podList.Items
+				return true, nil
+			})
+			// Verify zone spreading.
+			zoneCnts := make(map[string]int)
+			for _, p := range pods {
+				zoneCnts[zoneForNode[p.Spec.NodeName]]++
+			}
+			maxCnt := 0
+			minCnt := len(pods)
+			for _, c := range zoneCnts {
+				if c > maxCnt {
+					maxCnt = c
+				}
+				if c < minCnt {
+					minCnt = c
+				}
+			}
+			if skew := maxCnt - minCnt; skew != 0 {
+				t.Errorf("Zone skew is %d, should be 0", skew)
+			}
+		})
+	}
+}