rkt: Add '--hostname' support for rkt.

Add GeneratePodHostNameAndDomain() to RuntimeHelper to
get the hostname of the pod from kubelet.

Also update the logging flag to change the journal match from
_HOSTNAME to _MACHINE_ID.

pkg/kubelet/container/helpers.go

@@ -41,6 +41,7 @@ type HandlerRunner interface {
 type RuntimeHelper interface {
 	GenerateRunContainerOptions(pod *api.Pod, container *api.Container, podIP string) (*RunContainerOptions, error)
 	GetClusterDNS(pod *api.Pod) (dnsServers []string, dnsSearches []string, err error)
+	GeneratePodHostNameAndDomain(pod *api.Pod) (hostname string, hostDomain string)
 }
 
 // ShouldContainerBeRestarted checks whether a container needs to be restarted.

pkg/kubelet/dockertools/manager_test.go

@@ -84,6 +84,11 @@ func (f *fakeRuntimeHelper) GetClusterDNS(pod *api.Pod) ([]string, []string, err
 	return nil, nil, fmt.Errorf("not implemented")
 }
 
+// This is not used by docker runtime.
+func (f *fakeRuntimeHelper) GeneratePodHostNameAndDomain(pod *api.Pod) (string, string) {
+	return "", ""
+}
+
 func newTestDockerManagerWithHTTPClientWithVersion(fakeHTTPClient *fakeHTTP, version, apiVersion string) (*DockerManager, *FakeDockerClient) {
 	fakeDocker := NewFakeDockerClientWithVersion(version, apiVersion)
 	fakeRecorder := &record.FakeRecorder{}

pkg/kubelet/kubelet.go

@@ -1334,9 +1334,10 @@ func makePortMappings(container *api.Container) (ports []kubecontainer.PortMappi
 	return
 }
 
-func generatePodHostNameAndDomain(pod *api.Pod, clusterDomain string) (string, string) {
+func (kl *Kubelet) GeneratePodHostNameAndDomain(pod *api.Pod) (string, string) {
 	// TODO(vmarmol): Handle better.
 	// Cap hostname at 63 chars (specification is 64bytes which is 63 chars and the null terminating char).
+	clusterDomain := kl.clusterDomain
 	const hostnameMaxLen = 63
 	podAnnotations := pod.Annotations
 	if podAnnotations == nil {
@@ -1366,7 +1367,7 @@ func generatePodHostNameAndDomain(pod *api.Pod, clusterDomain string) (string, s
 func (kl *Kubelet) GenerateRunContainerOptions(pod *api.Pod, container *api.Container, podIP string) (*kubecontainer.RunContainerOptions, error) {
 	var err error
 	opts := &kubecontainer.RunContainerOptions{CgroupParent: kl.cgroupRoot}
-	hostname, hostDomainName := generatePodHostNameAndDomain(pod, kl.clusterDomain)
+	hostname, hostDomainName := kl.GeneratePodHostNameAndDomain(pod)
 	opts.Hostname = hostname
 	vol, ok := kl.volumeManager.GetVolumes(pod.UID)
 	if !ok {

pkg/kubelet/rkt/fake_rkt_interface_test.go

@@ -150,6 +150,8 @@ func (f *fakeSystemd) Reload() error {
 type fakeRuntimeHelper struct {
 	dnsServers  []string
 	dnsSearches []string
+	hostName    string
+	hostDomain  string
 	err         error
 }
 
@@ -160,3 +162,7 @@ func (f *fakeRuntimeHelper) GenerateRunContainerOptions(pod *api.Pod, container
 func (f *fakeRuntimeHelper) GetClusterDNS(pod *api.Pod) ([]string, []string, error) {
 	return f.dnsServers, f.dnsSearches, f.err
 }
+
+func (f *fakeRuntimeHelper) GeneratePodHostNameAndDomain(pod *api.Pod) (string, string) {
+	return f.hostName, f.hostDomain
+}

pkg/kubelet/rkt/log.go

@@ -23,6 +23,7 @@ import (
 	"io"
 	"os/exec"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -100,7 +101,8 @@ func pipeLog(wg *sync.WaitGroup, logOptions *api.PodLogOptions, r io.ReadCloser,
 // stream the log. Set |follow| to false and specify the number of lines (e.g.
 // "100" or "all") to tail the log.
 //
-// In rkt runtime's implementation, per container log is get via 'journalctl -m _HOSTNAME=[rkt-$UUID] -u [APP_NAME]'.
+// In rkt runtime's implementation, per container log is get via 'journalctl -m _MACHINE_ID=[MACHINE_ID] -u [APP_NAME]'.
+// Where MACHINE_ID is the rkt id without dash.
 // See https://github.com/coreos/rkt/blob/master/Documentation/commands.md#logging for more details.
 //
 // TODO(yifan): If the rkt is using lkvm as the stage1 image, then this function will fail.
@@ -110,8 +112,7 @@ func (r *Runtime) GetContainerLogs(pod *api.Pod, containerID kubecontainer.Conta
 		return err
 	}
 
-	cmd := exec.Command("journalctl", "-m", fmt.Sprintf("_HOSTNAME=rkt-%s", id.uuid), "-u", id.appName, "-a")
+	cmd := exec.Command("journalctl", "-m", fmt.Sprintf("_MACHINE_ID=%s", strings.Replace(id.uuid, "-", "", -1)), "-u", id.appName, "-a")
-
 	// Get the json structured logs.
 	cmd.Args = append(cmd.Args, "-o", "json")
 

pkg/kubelet/rkt/rkt.go

@@ -760,6 +760,10 @@ func (r *Runtime) generateRunCommand(pod *api.Pod, uuid string) (string, error)
 	if len(dnsServers) > 0 || len(dnsSearches) > 0 {
 		runPrepared = append(runPrepared, fmt.Sprintf("--dns-opt=%s", defaultDNSOption))
 	}
+
+	// TODO(yifan): host domain is not being used.
+	hostname, _ := r.runtimeHelper.GeneratePodHostNameAndDomain(pod)
+	runPrepared = append(runPrepared, fmt.Sprintf("--hostname=%s", hostname))
 	runPrepared = append(runPrepared, uuid)
 	return strings.Join(runPrepared, " "), nil
 }

pkg/kubelet/rkt/rkt_test.go

@@ -1037,6 +1037,7 @@ func TestGenerateRunCommand(t *testing.T) {
 
 		dnsServers  []string
 		dnsSearches []string
+		hostName    string
 		err         error
 
 		expect string
@@ -1044,26 +1045,38 @@ func TestGenerateRunCommand(t *testing.T) {
 		// Case #0, returns error.
 		{
 			&api.Pod{
+				ObjectMeta: api.ObjectMeta{
+					Name: "pod-name-foo",
+				},
 				Spec: api.PodSpec{},
 			},
 			"rkt-uuid-foo",
 			[]string{},
 			[]string{},
+			"",
 			fmt.Errorf("failed to get cluster dns"),
 			"",
 		},
 		// Case #1, returns no dns, with private-net.
 		{
-			&api.Pod{},
+			&api.Pod{
+				ObjectMeta: api.ObjectMeta{
+					Name: "pod-name-foo",
+				},
+			},
 			"rkt-uuid-foo",
 			[]string{},
 			[]string{},
+			"pod-hostname-foo",
 			nil,
-			"/bin/rkt/rkt --debug=false --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=rkt.kubernetes.io rkt-uuid-foo",
+			"/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=rkt.kubernetes.io --hostname=pod-hostname-foo rkt-uuid-foo",
 		},
 		// Case #2, returns no dns, with host-net.
 		{
 			&api.Pod{
+				ObjectMeta: api.ObjectMeta{
+					Name: "pod-name-foo",
+				},
 				Spec: api.PodSpec{
 					SecurityContext: &api.PodSecurityContext{
 						HostNetwork: true,
@@ -1073,12 +1086,16 @@ func TestGenerateRunCommand(t *testing.T) {
 			"rkt-uuid-foo",
 			[]string{},
 			[]string{},
+			"pod-hostname-foo",
 			nil,
-			"/bin/rkt/rkt --debug=false --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=host rkt-uuid-foo",
+			"/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=host --hostname=pod-hostname-foo rkt-uuid-foo",
 		},
 		// Case #3, returns dns, dns searches, with private-net.
 		{
 			&api.Pod{
+				ObjectMeta: api.ObjectMeta{
+					Name: "pod-name-foo",
+				},
 				Spec: api.PodSpec{
 					SecurityContext: &api.PodSecurityContext{
 						HostNetwork: false,
@@ -1088,12 +1105,16 @@ func TestGenerateRunCommand(t *testing.T) {
 			"rkt-uuid-foo",
 			[]string{"127.0.0.1"},
 			[]string{"."},
+			"pod-hostname-foo",
 			nil,
-			"/bin/rkt/rkt --debug=false --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=rkt.kubernetes.io --dns=127.0.0.1 --dns-search=. --dns-opt=ndots:5 rkt-uuid-foo",
+			"/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=rkt.kubernetes.io --dns=127.0.0.1 --dns-search=. --dns-opt=ndots:5 --hostname=pod-hostname-foo rkt-uuid-foo",
 		},
 		// Case #4, returns dns, dns searches, with host-network.
 		{
 			&api.Pod{
+				ObjectMeta: api.ObjectMeta{
+					Name: "pod-name-foo",
+				},
 				Spec: api.PodSpec{
 					SecurityContext: &api.PodSecurityContext{
 						HostNetwork: true,
@@ -1103,8 +1124,9 @@ func TestGenerateRunCommand(t *testing.T) {
 			"rkt-uuid-foo",
 			[]string{"127.0.0.1"},
 			[]string{"."},
+			"pod-hostname-foo",
 			nil,
-			"/bin/rkt/rkt --debug=false --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=host --dns=127.0.0.1 --dns-search=. --dns-opt=ndots:5 rkt-uuid-foo",
+			"/bin/rkt/rkt --insecure-options=image,ondisk --local-config=/var/rkt/local/data --dir=/var/data run-prepared --net=host --dns=127.0.0.1 --dns-search=. --dns-opt=ndots:5 --hostname=pod-hostname-foo rkt-uuid-foo",
 		},
 	}
 
@@ -1120,7 +1142,7 @@ func TestGenerateRunCommand(t *testing.T) {
 
 	for i, tt := range tests {
 		testCaseHint := fmt.Sprintf("test case #%d", i)
-		rkt.runtimeHelper = &fakeRuntimeHelper{tt.dnsServers, tt.dnsSearches, tt.err}
+		rkt.runtimeHelper = &fakeRuntimeHelper{tt.dnsServers, tt.dnsSearches, tt.hostName, "", tt.err}
 
 		result, err := rkt.generateRunCommand(tt.pod, tt.uuid)
 		assert.Equal(t, tt.err, err, testCaseHint)