kubelet_etc_hosts.go

/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package common

import (
	"io/ioutil"
	"os"
	"strings"
	"time"

	"github.com/golang/glog"
	. "github.com/onsi/ginkgo"
	"k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/kubernetes/test/e2e/framework"
	imageutils "k8s.io/kubernetes/test/utils/image"
)

const (
	etcHostsPodName            = "test-pod"
	etcHostsHostNetworkPodName = "test-host-network-pod"
	etcHostsPartialContent     = "# Kubernetes-managed hosts file."
)

var etcHostsImageName = imageutils.GetE2EImage(imageutils.Netexec)

type KubeletManagedHostConfig struct {
	hostNetworkPod *v1.Pod
	pod            *v1.Pod
	f              *framework.Framework
	tmpEtcHostFile *os.File
}

var _ = framework.KubeDescribe("KubeletManagedEtcHosts", func() {
	f := framework.NewDefaultFramework("e2e-kubelet-etc-hosts")
	config := &KubeletManagedHostConfig{
		f: f,
	}

	/*
		    Testname: kubelet-managed-etc-hosts
		    Description: Make sure Kubelet correctly manages /etc/hosts and mounts
			it into the container.
	*/
	framework.ConformanceIt("should test kubelet managed /etc/hosts file ", func() {
		By("Setting up the test")
		config.setup()

		By("Running the test")
		config.verifyEtcHosts()

		config.cleanup()
	})
})

func (config *KubeletManagedHostConfig) verifyEtcHosts() {
	By("Verifying /etc/hosts of container is kubelet-managed for pod with hostNetwork=false")
	assertManagedStatus(config, etcHostsPodName, true, "busybox-1")
	assertManagedStatus(config, etcHostsPodName, true, "busybox-2")

	By("Verifying /etc/hosts of container is not kubelet-managed since container specifies /etc/hosts mount")
	assertManagedStatus(config, etcHostsPodName, false, "busybox-3")

	By("Verifying /etc/hosts content of container is not kubelet-managed for pod with hostNetwork=true")
	assertManagedStatus(config, etcHostsHostNetworkPodName, false, "busybox-1")
	assertManagedStatus(config, etcHostsHostNetworkPodName, false, "busybox-2")
}

func (config *KubeletManagedHostConfig) setup() {
	etcHostContents := `127.0.0.1	localhost
::1	localhost ip6-localhost ip6-loopback
fe00::0	ip6-localnet
ff00::0	ip6-mcastprefix
ff02::1	ip6-allnodes
ff02::2	ip6-allrouters`

	// Write the data to a temp file.
	var err error
	config.tmpEtcHostFile, err = ioutil.TempFile("", "etc-hosts")
	if err != nil {
		framework.Failf("failed to create temp file for /etc/hosts: %v", err)
	}
	if _, err := config.tmpEtcHostFile.Write([]byte(etcHostContents)); err != nil {
		framework.Failf("Failed to write temp file for /etc/hosts data: %v", err)
	}
	if err := config.tmpEtcHostFile.Close(); err != nil {
		framework.Failf("Failed to close temp file: %v", err)
	}

	By("Creating hostNetwork=false pod")
	config.createPodWithoutHostNetwork()

	By("Creating hostNetwork=true pod")
	config.createPodWithHostNetwork()
}

func (config *KubeletManagedHostConfig) cleanup() {
	if config.tmpEtcHostFile != nil {
		os.Remove(config.tmpEtcHostFile.Name())
	}
}

func (config *KubeletManagedHostConfig) createPodWithoutHostNetwork() {
	podSpec := config.createPodSpec(etcHostsPodName)
	config.pod = config.f.PodClient().CreateSync(podSpec)
}

func (config *KubeletManagedHostConfig) createPodWithHostNetwork() {
	podSpec := config.createPodSpecWithHostNetwork(etcHostsHostNetworkPodName)
	config.hostNetworkPod = config.f.PodClient().CreateSync(podSpec)
}

func assertManagedStatus(
	config *KubeletManagedHostConfig, podName string, expectedIsManaged bool, name string) {
	// TODO: workaround for https://github.com/kubernetes/kubernetes/issues/34256
	//
	// Retry until timeout for the contents of /etc/hosts to show
	// up. Note: if /etc/hosts is properly mounted, then this will
	// succeed immediately.
	const retryTimeout = 30 * time.Second

	retryCount := 0
	etcHostsContent := ""

	for startTime := time.Now(); time.Since(startTime) < retryTimeout; {
		etcHostsContent = config.getEtcHostsContent(podName, name)
		isManaged := strings.Contains(etcHostsContent, etcHostsPartialContent)

		if expectedIsManaged == isManaged {
			return
		}

		glog.Warningf(
			"For pod: %s, name: %s, expected %t, actual %t (/etc/hosts was %q), retryCount: %d",
			podName, name, expectedIsManaged, isManaged, etcHostsContent, retryCount)

		retryCount++
		time.Sleep(100 * time.Millisecond)
	}

	if expectedIsManaged {
		framework.Failf(
			"/etc/hosts file should be kubelet managed (name: %s, retries: %d). /etc/hosts contains %q",
			name, retryCount, etcHostsContent)
	} else {
		framework.Failf(
			"/etc/hosts file should no be kubelet managed (name: %s, retries: %d). /etc/hosts contains %q",
			name, retryCount, etcHostsContent)
	}
}

func (config *KubeletManagedHostConfig) getEtcHostsContent(podName, containerName string) string {
	return config.f.ExecCommandInContainer(podName, containerName, "cat", "/etc/hosts")
}

func (config *KubeletManagedHostConfig) createPodSpec(podName string) *v1.Pod {
	hostPathType := new(v1.HostPathType)
	*hostPathType = v1.HostPathType(string(v1.HostPathFileOrCreate))
	pod := &v1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name: podName,
		},
		Spec: v1.PodSpec{
			Containers: []v1.Container{
				{
					Name:            "busybox-1",
					Image:           etcHostsImageName,
					ImagePullPolicy: v1.PullIfNotPresent,
					Command: []string{
						"sleep",
						"900",
					},
				},
				{
					Name:            "busybox-2",
					Image:           etcHostsImageName,
					ImagePullPolicy: v1.PullIfNotPresent,
					Command: []string{
						"sleep",
						"900",
					},
				},
				{
					Name:            "busybox-3",
					Image:           etcHostsImageName,
					ImagePullPolicy: v1.PullIfNotPresent,
					Command: []string{
						"sleep",
						"900",
					},
					VolumeMounts: []v1.VolumeMount{
						{
							Name:      "host-etc-hosts",
							MountPath: "/etc/hosts",
						},
					},
				},
			},
			Volumes: []v1.Volume{
				{
					Name: "host-etc-hosts",
					VolumeSource: v1.VolumeSource{
						HostPath: &v1.HostPathVolumeSource{
							Path: config.tmpEtcHostFile.Name(),
							Type: hostPathType,
						},
					},
				},
			},
		},
	}
	return pod
}

func (config *KubeletManagedHostConfig) createPodSpecWithHostNetwork(podName string) *v1.Pod {
	pod := &v1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name: podName,
		},
		Spec: v1.PodSpec{
			HostNetwork:     true,
			SecurityContext: &v1.PodSecurityContext{},
			Containers: []v1.Container{
				{
					Name:            "busybox-1",
					Image:           etcHostsImageName,
					ImagePullPolicy: v1.PullIfNotPresent,
					Command: []string{
						"sleep",
						"900",
					},
				},
				{
					Name:            "busybox-2",
					Image:           etcHostsImageName,
					ImagePullPolicy: v1.PullIfNotPresent,
					Command: []string{
						"sleep",
						"900",
					},
				},
			},
		},
	}
	return pod
}