Merge pull request kubernetes#76508 from bclau/tests/agnhost-custom-dns-test

tests: Adds configurable pod DNS nameservers and search list test

Author: k8s-ci-robot

test/e2e/framework/util.go

@@ -4865,6 +4865,25 @@ func (f *Framework) NewTestPod(name string, requests v1.ResourceList, limits v1.
 	}
 }
 
+// NewAgnhostPod returns a pod that uses the agnhost image. The image's binary supports various subcommands
+// that behave the same, no matter the underlying OS.
+func (f *Framework) NewAgnhostPod(name string, args ...string) *v1.Pod {
+	return &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: name,
+		},
+		Spec: v1.PodSpec{
+			Containers: []v1.Container{
+				{
+					Name:  "agnhost",
+					Image: imageutils.GetE2EImage(imageutils.Agnhost),
+					Args:  args,
+				},
+			},
+		},
+	}
+}
+
 // CreateEmptyFileOnPod creates empty file at given path on the pod.
 func CreateEmptyFileOnPod(namespace string, podName string, filePath string) error {
 	_, err := RunKubectl("exec", fmt.Sprintf("--namespace=%s", namespace), podName, "--", "/bin/sh", "-c", fmt.Sprintf("touch %s", filePath))

test/e2e/network/dns.go

@@ -362,6 +362,54 @@ var _ = SIGDescribe("DNS", func() {
 		validateTargetedProbeOutput(f, pod3, []string{wheezyFileName, jessieFileName}, svc.Spec.ClusterIP)
 	})
 
+	It("should support configurable pod DNS nameservers", func() {
+		By("Creating a pod with dnsPolicy=None and customized dnsConfig...")
+		testServerIP := "1.1.1.1"
+		testSearchPath := "resolv.conf.local"
+		testAgnhostPod := f.NewAgnhostPod(f.Namespace.Name, "pause")
+		testAgnhostPod.Spec.DNSPolicy = v1.DNSNone
+		testAgnhostPod.Spec.DNSConfig = &v1.PodDNSConfig{
+			Nameservers: []string{testServerIP},
+			Searches:    []string{testSearchPath},
+		}
+		testAgnhostPod, err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).Create(testAgnhostPod)
+		Expect(err).NotTo(HaveOccurred(), "failed to create pod: %s", testAgnhostPod.Name)
+		framework.Logf("Created pod %v", testAgnhostPod)
+		defer func() {
+			framework.Logf("Deleting pod %s...", testAgnhostPod.Name)
+			if err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).Delete(testAgnhostPod.Name, metav1.NewDeleteOptions(0)); err != nil {
+				framework.Failf("Failed to delete pod %s: %v", testAgnhostPod.Name, err)
+			}
+		}()
+		Expect(f.WaitForPodRunning(testAgnhostPod.Name)).NotTo(HaveOccurred(), "failed to wait for pod %s to be running", testAgnhostPod.Name)
+
+		runCommand := func(arg string) string {
+			cmd := []string{"/agnhost", arg}
+			stdout, stderr, err := f.ExecWithOptions(framework.ExecOptions{
+				Command:       cmd,
+				Namespace:     f.Namespace.Name,
+				PodName:       testAgnhostPod.Name,
+				ContainerName: "agnhost",
+				CaptureStdout: true,
+				CaptureStderr: true,
+			})
+			Expect(err).NotTo(HaveOccurred(), "failed to run command '/agnhost %s' on pod, stdout: %v, stderr: %v, err: %v", arg, stdout, stderr, err)
+			return stdout
+		}
+
+		By("Verifying customized DNS suffix list is configured on pod...")
+		stdout := runCommand("dns-suffix")
+		if !strings.Contains(stdout, testSearchPath) {
+			framework.Failf("customized DNS suffix list not found configured in pod, expected to contain: %s, got: %s", testSearchPath, stdout)
+		}
+
+		By("Verifying customized DNS server is configured on pod...")
+		stdout = runCommand("dns-server-list")
+		if !strings.Contains(stdout, testServerIP) {
+			framework.Failf("customized DNS server not found in configured in pod, expected to contain: %s, got: %s", testServerIP, stdout)
+		}
+	})
+
 	It("should support configurable pod resolv.conf", func() {
 		By("Preparing a test DNS service with injected DNS names...")
 		testInjectedIP := "1.1.1.1"