Merge pull request #11050 from marekbiskup/dns-example-e2e

e2e test for dns example

test/e2e/examples.go

@@ -18,6 +18,8 @@ package e2e
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 	"time"
@@ -34,8 +36,17 @@ import (
 const (
 	podListTimeout     = time.Minute
 	serverStartTimeout = podStartTimeout + 3*time.Minute
+	dnsReadyTimeout    = time.Minute
 )
 
+const queryDnsPythonTemplate string = `
+import socket
+try:
+	socket.gethostbyname('%s')
+	print 'ok'
+except:
+	print 'err'`
+
 var _ = Describe("Examples e2e", func() {
 	var c *client.Client
 	var ns string
@@ -412,6 +423,103 @@ var _ = Describe("Examples e2e", func() {
 			})
 		})
 	})
+
+	Describe("[Example]ClusterDns", func() {
+		It("should create pod that uses dns", func() {
+			mkpath := func(file string) string {
+				return filepath.Join(testContext.RepoRoot, "examples/cluster-dns", file)
+			}
+
+			// contrary to the example, this test does not use contexts, for simplicity
+			// namespaces are passed directly.
+			// Also, for simplicity, we don't use yamls with namespaces, but we
+			// create testing namespaces instead.
+
+			backendRcYaml := mkpath("dns-backend-rc.yaml")
+			backendRcName := "dns-backend"
+			backendSvcYaml := mkpath("dns-backend-service.yaml")
+			backendSvcName := "dns-backend"
+			backendPodName := "dns-backend"
+			frontendPodYaml := mkpath("dns-frontend-pod.yaml")
+			frontendPodName := "dns-frontend"
+			frontendPodContainerName := "dns-frontend"
+
+			podOutput := "Hello World!"
+
+			// we need two namespaces anyway, so let's forget about
+			// the one created in BeforeEach and create two new ones.
+			namespaces := []*api.Namespace{nil, nil}
+			for i := range namespaces {
+				var err error
+				namespaces[i], err = createTestingNS(fmt.Sprintf("dnsexample%d", i), c)
+				if namespaces[i] != nil {
+					defer c.Namespaces().Delete(namespaces[i].Name)
+				}
+				Expect(err).NotTo(HaveOccurred())
+			}
+
+			for _, ns := range namespaces {
+				runKubectl("create", "-f", backendRcYaml, getNsCmdFlag(ns))
+			}
+
+			for _, ns := range namespaces {
+				runKubectl("create", "-f", backendSvcYaml, getNsCmdFlag(ns))
+			}
+
+			// wait for objects
+			for _, ns := range namespaces {
+				waitForRCPodsRunning(c, ns.Name, backendRcName)
+				waitForService(c, ns.Name, backendSvcName, true, poll, serviceStartTimeout)
+			}
+			// it is not enough that pods are running because they may be set to running, but
+			// the application itself may have not been initialized. Just query the application.
+			for _, ns := range namespaces {
+				label := labels.SelectorFromSet(labels.Set(map[string]string{"name": backendRcName}))
+				pods, err := c.Pods(ns.Name).List(label, fields.Everything())
+				Expect(err).NotTo(HaveOccurred())
+				err = podsResponding(c, ns.Name, backendPodName, false, pods)
+				Expect(err).NotTo(HaveOccurred(), "waiting for all pods to respond")
+				Logf("found %d backend pods responding in namespace %s", len(pods.Items), ns.Name)
+
+				err = serviceResponding(c, ns.Name, backendSvcName)
+				Expect(err).NotTo(HaveOccurred(), "waiting for the service to respond")
+			}
+
+			// Now another tricky part:
+			// It may happen that the service name is not yet in DNS.
+			// So if we start our pod, it will fail. We must make sure
+			// the name is already resolvable. So let's try to query DNS from
+			// the pod we have, until we find our service name.
+			// This complicated code may be removed if the pod itself retried after
+			// dns error or timeout.
+			// This code is probably unnecessary, but let's stay on the safe side.
+			label := labels.SelectorFromSet(labels.Set(map[string]string{"name": backendPodName}))
+			pods, err := c.Pods(namespaces[0].Name).List(label, fields.Everything())
+
+			if err != nil || pods == nil || len(pods.Items) == 0 {
+				Failf("no running pods found")
+			}
+			podName := pods.Items[0].Name
+
+			queryDns := fmt.Sprintf(queryDnsPythonTemplate, backendSvcName+"."+namespaces[0].Name)
+			_, err = lookForStringInPodExec(namespaces[0].Name, podName, []string{"python", "-c", queryDns}, "ok", dnsReadyTimeout)
+			Expect(err).NotTo(HaveOccurred(), "waiting for output from pod exec")
+
+			updatedPodYaml := prepareResourceWithReplacedString(frontendPodYaml, "dns-backend.development.cluster.local", fmt.Sprintf("dns-backend.%s.cluster.local", namespaces[0].Name))
+
+			// create a pod in each namespace
+			for _, ns := range namespaces {
+				newKubectlCommand("create", "-f", "-", getNsCmdFlag(ns)).withStdinData(updatedPodYaml).exec()
+			}
+			// remember that we cannot wait for the pods to be running because our pods terminate by themselves.
+
+			// wait for pods to print their result
+			for _, ns := range namespaces {
+				_, err := lookForStringInLog(ns.Name, frontendPodName, frontendPodContainerName, podOutput, podStartTimeout)
+				Expect(err).NotTo(HaveOccurred())
+			}
+		})
+	})
 })
 
 func makeHttpRequestToService(c *client.Client, ns, service, path string) (string, error) {
@@ -426,6 +534,21 @@ func makeHttpRequestToService(c *client.Client, ns, service, path string) (strin
 	return string(result), err
 }
 
+func getNsCmdFlag(ns *api.Namespace) string {
+	return fmt.Sprintf("--namespace=%v", ns.Name)
+}
+
+// pass enough context with the 'old' parameter so that it replaces what your really intended.
+func prepareResourceWithReplacedString(inputFile, old, new string) string {
+	f, err := os.Open(inputFile)
+	Expect(err).NotTo(HaveOccurred())
+	defer f.Close()
+	data, err := ioutil.ReadAll(f)
+	Expect(err).NotTo(HaveOccurred())
+	podYaml := strings.Replace(string(data), old, new, 1)
+	return podYaml
+}
+
 func forEachPod(c *client.Client, ns, selectorKey, selectorValue string, fn func(api.Pod)) {
 	var pods *api.PodList
 	var err error
@@ -458,6 +581,15 @@ func lookForStringInFile(ns, podName, container, file, expectedString string, ti
 	})
 }
 
+func lookForStringInPodExec(ns, podName string, command []string, expectedString string, timeout time.Duration) (result string, err error) {
+	return lookForString(expectedString, timeout, func() string {
+		// use the first container
+		args := []string{"exec", podName, fmt.Sprintf("--namespace=%v", ns), "--"}
+		args = append(args, command...)
+		return runKubectl(args...)
+	})
+}
+
 // Looks for the given string in the output of fn, repeatedly calling fn until
 // the timeout is reached or the string is found. Returns last log and possibly
 // error if the string was not found.
@@ -468,6 +600,6 @@ func lookForString(expectedString string, timeout time.Duration, fn func() strin
 			return
 		}
 	}
-	err = fmt.Errorf("Failed to find \"%s\"", expectedString)
+	err = fmt.Errorf("Failed to find \"%s\", last result: \"%s\"", expectedString, result)
 	return
 }

test/e2e/resize_nodes.go

@@ -290,14 +290,6 @@ func podsRunning(c *client.Client, pods *api.PodList) []error {
 	return e
 }
 
-func podsResponding(c *client.Client, ns, name string, wantName bool, pods *api.PodList) error {
-	By("trying to dial each unique pod")
-	retryTimeout := 2 * time.Minute
-	retryInterval := 5 * time.Second
-	label := labels.SelectorFromSet(labels.Set(map[string]string{"name": name}))
-	return wait.Poll(retryInterval, retryTimeout, podResponseChecker{c, ns, label, name, wantName, pods}.checkAllResponses)
-}
-
 func verifyPods(c *client.Client, ns, name string, wantName bool, replicas int) error {
 	pods, err := podsCreated(c, ns, name, replicas)
 	if err != nil {

test/e2e/util.go

@@ -87,6 +87,9 @@ const (
 	// be "ready" before the test starts, so this is small.
 	podReadyBeforeTimeout = 20 * time.Second
 
+	podRespondingTimeout     = 2 * time.Minute
+	serviceRespondingTimeout = 2 * time.Minute
+
 	// How wide to print pod names, by default. Useful for aligning printing to
 	// quickly scan through output.
 	podPrintWidth = 55
@@ -700,6 +703,37 @@ func (r podResponseChecker) checkAllResponses() (done bool, err error) {
 	return true, nil
 }
 
+func podsResponding(c *client.Client, ns, name string, wantName bool, pods *api.PodList) error {
+	By("trying to dial each unique pod")
+	label := labels.SelectorFromSet(labels.Set(map[string]string{"name": name}))
+	return wait.Poll(poll, podRespondingTimeout, podResponseChecker{c, ns, label, name, wantName, pods}.checkAllResponses)
+}
+
+func serviceResponding(c *client.Client, ns, name string) error {
+	By(fmt.Sprintf("trying to dial the service %s.%s via the proxy", ns, name))
+
+	return wait.Poll(poll, serviceRespondingTimeout, func() (done bool, err error) {
+		body, err := c.Get().
+			Prefix("proxy").
+			Namespace(ns).
+			Resource("services").
+			Name(name).
+			Do().
+			Raw()
+		if err != nil {
+			Logf("Failed to GET from service %s: %v:", name, err)
+			return false, nil
+		}
+		got := string(body)
+		if len(got) == 0 {
+			Logf("Service %s: expected non-empty response", name)
+			return false, err // stop polling
+		}
+		Logf("Service %s: found nonempty answer: %s", name, got)
+		return true, nil
+	})
+}
+
 func loadConfig() (*client.Config, error) {
 	switch {
 	case testContext.KubeConfig != "":
@@ -861,12 +895,29 @@ func kubectlCmd(args ...string) *exec.Cmd {
 	return cmd
 }
 
-func runKubectl(args ...string) string {
+// kubectlBuilder is used to build, custimize and execute a kubectl Command.
+// Add more functions to customize the builder as needed.
+type kubectlBuilder struct {
+	cmd *exec.Cmd
+}
+
+func newKubectlCommand(args ...string) *kubectlBuilder {
+	b := new(kubectlBuilder)
+	b.cmd = kubectlCmd(args...)
+	return b
+}
+
+func (b kubectlBuilder) withStdinData(data string) *kubectlBuilder {
+	b.cmd.Stdin = strings.NewReader(data)
+	return &b
+}
+
+func (b kubectlBuilder) exec() string {
 	var stdout, stderr bytes.Buffer
-	cmd := kubectlCmd(args...)
+	cmd := b.cmd
 	cmd.Stdout, cmd.Stderr = &stdout, &stderr
 
-	Logf("Running '%s %s'", cmd.Path, strings.Join(cmd.Args, " "))
+	Logf("Running '%s %s'", cmd.Path, strings.Join(cmd.Args[1:], " ")) // skip arg[0] as it is printed separately
 	if err := cmd.Run(); err != nil {
 		Failf("Error running %v:\nCommand stdout:\n%v\nstderr:\n%v\n", cmd, cmd.Stdout, cmd.Stderr)
 		return ""
@@ -876,6 +927,11 @@ func runKubectl(args ...string) string {
 	return strings.TrimSpace(stdout.String())
 }
 
+// runKubectl is a convenience wrapper over kubectlBuilder
+func runKubectl(args ...string) string {
+	return newKubectlCommand(args...).exec()
+}
+
 func startCmdAndStreamOutput(cmd *exec.Cmd) (stdout, stderr io.ReadCloser, err error) {
 	stdout, err = cmd.StdoutPipe()
 	if err != nil {