tests: Replaces dnsutils image used with agnhost (part 4)

Quite a few images are only used a few times in a few tests. Thus,
the images are being centralized into the agnhost image, reducing
the number of images that have to be pulled and used.

This PR replaces the usage of the following images with agnhost:

- dnsutils

dnsmasq is a Linux specific binary. In order for the tests to also
pass on Windows, CoreDNS should be used instead.

test/e2e/network/dns.go

@@ -460,10 +460,20 @@ var _ = SIGDescribe("DNS", func() {
 		testSearchPath := "resolv.conf.local"
 		testDNSNameFull := fmt.Sprintf("%s.%s", testDNSNameShort, testSearchPath)
 
-		testServerPod := generateDNSServerPod(map[string]string{
+		corednsConfig := generateCoreDNSConfigmap(f.Namespace.Name, map[string]string{
 			testDNSNameFull: testInjectedIP,
 		})
-		testServerPod, err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).Create(context.TODO(), testServerPod, metav1.CreateOptions{})
+		corednsConfig, err := f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Create(context.TODO(), corednsConfig, metav1.CreateOptions{})
+		framework.ExpectNoError(err, "unable to create test configMap %s", corednsConfig.Name)
+
+		defer func() {
+			framework.Logf("Deleting configmap %s...", corednsConfig.Name)
+			err := f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Delete(context.TODO(), corednsConfig.Name, nil)
+			framework.ExpectNoError(err, "Failed to delete configmap %s: %v", corednsConfig.Name)
+		}()
+
+		testServerPod := generateCoreDNSServerPod(corednsConfig)
+		testServerPod, err = f.ClientSet.CoreV1().Pods(f.Namespace.Name).Create(context.TODO(), testServerPod, metav1.CreateOptions{})
 		framework.ExpectNoError(err, "failed to create pod: %s", testServerPod.Name)
 		framework.Logf("Created pod %v", testServerPod)
 		defer func() {
@@ -528,7 +538,7 @@ var _ = SIGDescribe("DNS", func() {
 		// This verifies both:
 		// - Custom search path is appended.
 		// - DNS query is sent to the specified server.
-		cmd = []string{"/usr/bin/dig", "+short", "+search", testDNSNameShort}
+		cmd = []string{"dig", "+short", "+search", testDNSNameShort}
 		digFunc := func() (bool, error) {
 			stdout, stderr, err := f.ExecWithOptions(framework.ExecOptions{
 				Command:       cmd,

test/e2e/network/dns_common.go

@@ -19,6 +19,7 @@ package network
 import (
 	"context"
 	"fmt"
+	"regexp"
 	"strings"
 	"time"
 
@@ -40,6 +41,9 @@ import (
 	"github.com/onsi/gomega"
 )
 
+// Windows output can contain additional \r
+var newLineRegexp = regexp.MustCompile("\r?\n")
+
 type dnsTestCommon struct {
 	f      *framework.Framework
 	c      clientset.Interface
@@ -104,7 +108,7 @@ func (t *dnsTestCommon) checkDNSRecordFrom(name string, predicate func([]string)
 
 // runDig queries for `dnsName`. Returns a list of responses.
 func (t *dnsTestCommon) runDig(dnsName, target string) []string {
-	cmd := []string{"/usr/bin/dig", "+short"}
+	cmd := []string{"dig", "+short"}
 	switch target {
 	case "coredns":
 		cmd = append(cmd, "@"+t.dnsPod.Status.PodIP)
@@ -135,7 +139,7 @@ func (t *dnsTestCommon) runDig(dnsName, target string) []string {
 	if stdout == "" {
 		return []string{}
 	}
-	return strings.Split(stdout, "\n")
+	return newLineRegexp.Split(stdout, -1)
 }
 
 func (t *dnsTestCommon) setConfigMap(cm *v1.ConfigMap) {
@@ -208,7 +212,7 @@ func (t *dnsTestCommon) createUtilPodLabel(baseName string) {
 			Containers: []v1.Container{
 				{
 					Name:    "util",
-					Image:   imageutils.GetE2EImage(imageutils.Dnsutils),
+					Image:   imageutils.GetE2EImage(imageutils.Agnhost),
 					Command: []string{"sleep", "10000"},
 					Ports: []v1.ContainerPort{
 						{ContainerPort: servicePort, Protocol: v1.ProtocolTCP},
@@ -274,8 +278,8 @@ func (t *dnsTestCommon) deleteCoreDNSPods() {
 	}
 }
 
-func generateDNSServerPod(aRecords map[string]string) *v1.Pod {
-	pod := &v1.Pod{
+func generateCoreDNSServerPod(corednsConfig *v1.ConfigMap) *v1.Pod {
+	return &v1.Pod{
 		TypeMeta: metav1.TypeMeta{
 			Kind: "Pod",
 		},
@@ -283,29 +287,61 @@ func generateDNSServerPod(aRecords map[string]string) *v1.Pod {
 			GenerateName: "e2e-dns-configmap-dns-server-",
 		},
 		Spec: v1.PodSpec{
+			Volumes: []v1.Volume{
+				{
+					Name: "coredns-config",
+					VolumeSource: v1.VolumeSource{
+						ConfigMap: &v1.ConfigMapVolumeSource{
+							LocalObjectReference: v1.LocalObjectReference{
+								Name: corednsConfig.Name,
+							},
+						},
+					},
+				},
+			},
 			Containers: []v1.Container{
 				{
 					Name:  "dns",
-					Image: imageutils.GetE2EImage(imageutils.Dnsutils),
+					Image: imageutils.GetE2EImage(imageutils.Agnhost),
 					Command: []string{
-						"/usr/sbin/dnsmasq",
-						"-u", "root",
-						"-k",
-						"--log-facility", "-",
-						"-q",
+						"/coredns",
+						"-conf", "/etc/coredns/Corefile",
+					},
+					VolumeMounts: []v1.VolumeMount{
+						{
+							Name:      "coredns-config",
+							MountPath: "/etc/coredns",
+							ReadOnly:  true,
+						},
 					},
 				},
 			},
 			DNSPolicy: "Default",
 		},
 	}
+}
 
+func generateCoreDNSConfigmap(namespaceName string, aRecords map[string]string) *v1.ConfigMap {
+	entries := ""
 	for name, ip := range aRecords {
-		pod.Spec.Containers[0].Command = append(
-			pod.Spec.Containers[0].Command,
-			fmt.Sprintf("-A/%v/%v", name, ip))
+		entries += fmt.Sprintf("\n\t\t%v %v", ip, name)
+	}
+
+	corefileData := fmt.Sprintf(`. {
+	hosts {%s
+	}
+	log
+}`, entries)
+
+	return &v1.ConfigMap{
+		ObjectMeta: metav1.ObjectMeta{
+			Namespace:    namespaceName,
+			GenerateName: "e2e-coredns-configmap-",
+		},
+		Data: map[string]string{
+			"Corefile": corefileData,
+		},
 	}
-	return pod
 }
 
 func (t *dnsTestCommon) createDNSPodFromObj(pod *v1.Pod) {
@@ -322,47 +358,26 @@ func (t *dnsTestCommon) createDNSPodFromObj(pod *v1.Pod) {
 	framework.ExpectNoError(err, "failed to get pod: %s", t.dnsServerPod.Name)
 }
 
-func (t *dnsTestCommon) createDNSServer(aRecords map[string]string) {
-	t.createDNSPodFromObj(generateDNSServerPod(aRecords))
+func (t *dnsTestCommon) createDNSServer(namespace string, aRecords map[string]string) {
+	corednsConfig := generateCoreDNSConfigmap(namespace, aRecords)
+	corednsConfig, err := t.c.CoreV1().ConfigMaps(namespace).Create(context.TODO(), corednsConfig, metav1.CreateOptions{})
+	if err != nil {
+		framework.Failf("unable to create test configMap %s: %v", corednsConfig.Name, err)
+	}
+
+	t.createDNSPodFromObj(generateCoreDNSServerPod(corednsConfig))
 }
 
-func (t *dnsTestCommon) createDNSServerWithPtrRecord(isIPv6 bool) {
-	pod := &v1.Pod{
-		TypeMeta: metav1.TypeMeta{
-			Kind: "Pod",
-		},
-		ObjectMeta: metav1.ObjectMeta{
-			GenerateName: "e2e-dns-configmap-dns-server-",
-		},
-		Spec: v1.PodSpec{
-			Containers: []v1.Container{
-				{
-					Name:  "dns",
-					Image: imageutils.GetE2EImage(imageutils.Dnsutils),
-					Command: []string{
-						"/usr/sbin/dnsmasq",
-						"-u", "root",
-						"-k",
-						"--log-facility", "-",
-						"-q",
-					},
-				},
-			},
-			DNSPolicy: "Default",
-		},
-	}
-
+func (t *dnsTestCommon) createDNSServerWithPtrRecord(namespace string, isIPv6 bool) {
+	// NOTE: PTR records are generated automatically by CoreDNS. So, if we're creating A records, we're
+	// going to also have PTR records. See: https://coredns.io/plugins/hosts/
+	var aRecords map[string]string
 	if isIPv6 {
-		pod.Spec.Containers[0].Command = append(
-			pod.Spec.Containers[0].Command,
-			fmt.Sprintf("--host-record=my.test,2001:db8::29"))
+		aRecords = map[string]string{"my.test": "2001:db8::29"}
 	} else {
-		pod.Spec.Containers[0].Command = append(
-			pod.Spec.Containers[0].Command,
-			fmt.Sprintf("--host-record=my.test,192.0.2.123"))
+		aRecords = map[string]string{"my.test": "192.0.2.123"}
 	}
-
-	t.createDNSPodFromObj(pod)
+	t.createDNSServer(namespace, aRecords)
 }
 
 func (t *dnsTestCommon) deleteDNSServerPod() {
@@ -413,7 +428,7 @@ func createDNSPod(namespace, wheezyProbeCmd, jessieProbeCmd, podHostName, servic
 				},
 				{
 					Name:    "querier",
-					Image:   imageutils.GetE2EImage(imageutils.Dnsutils),
+					Image:   imageutils.GetE2EImage(imageutils.Agnhost),
 					Command: []string{"sh", "-c", wheezyProbeCmd},
 					VolumeMounts: []v1.VolumeMount{
 						{
@@ -622,7 +637,7 @@ func generateDNSUtilsPod() *v1.Pod {
 			Containers: []v1.Container{
 				{
 					Name:    "util",
-					Image:   imageutils.GetE2EImage(imageutils.Dnsutils),
+					Image:   imageutils.GetE2EImage(imageutils.Agnhost),
 					Command: []string{"sleep", "10000"},
 				},
 			},

test/e2e/network/dns_configmap.go

@@ -221,13 +221,13 @@ func (t *dnsNameserverTest) run(isIPv6 bool) {
 	defer t.restoreDNSConfigMap(originalConfigMapData)
 
 	if isIPv6 {
-		t.createDNSServer(map[string]string{
+		t.createDNSServer(t.f.Namespace.Name, map[string]string{
 			"abc.acme.local": "2606:4700:4700::1111",
 			"def.acme.local": "2606:4700:4700::2222",
 			"widget.local":   "2606:4700:4700::3333",
 		})
 	} else {
-		t.createDNSServer(map[string]string{
+		t.createDNSServer(t.f.Namespace.Name, map[string]string{
 			"abc.acme.local": "1.1.1.1",
 			"def.acme.local": "2.2.2.2",
 			"widget.local":   "3.3.3.3",
@@ -317,7 +317,7 @@ func (t *dnsPtrFwdTest) run(isIPv6 bool) {
 	originalConfigMapData := t.fetchDNSConfigMapData()
 	defer t.restoreDNSConfigMap(originalConfigMapData)
 
-	t.createDNSServerWithPtrRecord(isIPv6)
+	t.createDNSServerWithPtrRecord(t.f.Namespace.Name, isIPv6)
 	defer t.deleteDNSServerPod()
 
 	// Should still be able to lookup public nameserver without explicit upstream nameserver set.
@@ -401,11 +401,11 @@ func (t *dnsExternalNameTest) run(isIPv6 bool) {
 
 	fooHostname := "foo.example.com"
 	if isIPv6 {
-		t.createDNSServer(map[string]string{
+		t.createDNSServer(t.f.Namespace.Name, map[string]string{
 			fooHostname: "2001:db8::29",
 		})
 	} else {
-		t.createDNSServer(map[string]string{
+		t.createDNSServer(t.f.Namespace.Name, map[string]string{
 			fooHostname: "192.0.2.123",
 		})
 	}

test/e2e/windows/dns.go

@@ -102,7 +102,7 @@ func generateDNSUtilsPod() *v1.Pod {
 			Containers: []v1.Container{
 				{
 					Name:    "util",
-					Image:   imageutils.GetE2EImage(imageutils.Dnsutils),
+					Image:   imageutils.GetE2EImage(imageutils.Agnhost),
 					Command: []string{"sleep", "10000"},
 				},
 			},

test/utils/image/manifest.go

@@ -70,6 +70,7 @@ func initReg() RegistryList {
 		DockerLibraryRegistry:   "docker.io/library",
 		DockerGluster:           "docker.io/gluster",
 		E2eRegistry:             "gcr.io/kubernetes-e2e-test-images",
+		// TODO: After the domain flip, this should instead be k8s.gcr.io/k8s-artifacts-prod/e2e-test-images
 		PromoterE2eRegistry:     "us.gcr.io/k8s-artifacts-prod/e2e-test-images",
 		InvalidRegistry:         "invalid.com/invalid",
 		GcRegistry:              "k8s.gcr.io",
@@ -139,8 +140,6 @@ const (
 	CudaVectorAdd
 	// CudaVectorAdd2 image
 	CudaVectorAdd2
-	// Dnsutils image
-	Dnsutils
 	// EchoServer image
 	EchoServer
 	// Etcd image
@@ -216,7 +215,6 @@ func initImageConfigs() map[int]Config {
 	configs[CheckMetadataConcealment] = Config{e2eRegistry, "metadata-concealment", "1.2"}
 	configs[CudaVectorAdd] = Config{e2eRegistry, "cuda-vector-add", "1.0"}
 	configs[CudaVectorAdd2] = Config{e2eRegistry, "cuda-vector-add", "2.0"}
-	configs[Dnsutils] = Config{e2eRegistry, "dnsutils", "1.1"}
 	configs[EchoServer] = Config{e2eRegistry, "echoserver", "2.2"}
 	configs[Etcd] = Config{gcRegistry, "etcd", "3.4.3"}
 	configs[GlusterDynamicProvisioner] = Config{dockerGluster, "glusterdynamic-provisioner", "v1.0"}