Use existing method to get Docker version.

pkg/kubelet/dockertools/docker.go

@@ -104,7 +104,7 @@ type dockerContainerCommandRunner struct {
 var dockerAPIVersionWithExec = []uint{1, 15}
 
 // Returns the major and minor version numbers of docker server.
-func (d *dockerContainerCommandRunner) getDockerServerVersion() ([]uint, error) {
+func (d *dockerContainerCommandRunner) GetDockerServerVersion() ([]uint, error) {
 	env, err := d.client.Version()
 	if err != nil {
 		return nil, fmt.Errorf("failed to get docker server version - %v", err)
@@ -127,7 +127,7 @@ func (d *dockerContainerCommandRunner) getDockerServerVersion() ([]uint, error)
 }
 
 func (d *dockerContainerCommandRunner) nativeExecSupportExists() (bool, error) {
-	version, err := d.getDockerServerVersion()
+	version, err := d.GetDockerServerVersion()
 	if err != nil {
 		return false, err
 	}
@@ -626,4 +626,5 @@ func parseImageName(image string) (string, string) {
 
 type ContainerCommandRunner interface {
 	RunInContainer(containerID string, cmd []string) ([]byte, error)
+	GetDockerServerVersion() ([]uint, error)
 }

pkg/kubelet/dockertools/docker_test.go

@@ -123,7 +123,7 @@ func TestContainerManifestNaming(t *testing.T) {
 func TestGetDockerServerVersion(t *testing.T) {
 	fakeDocker := &FakeDockerClient{VersionInfo: docker.Env{"Client version=1.2", "Server version=1.1.3", "Server API version=1.15"}}
 	runner := dockerContainerCommandRunner{fakeDocker}
-	version, err := runner.getDockerServerVersion()
+	version, err := runner.GetDockerServerVersion()
 	if err != nil {
 		t.Errorf("got error while getting docker server version - %s", err)
 	}

pkg/kubelet/kubelet.go

@@ -1362,20 +1362,12 @@ func (kl *Kubelet) syncLoop(updates <-chan PodUpdate, handler SyncHandler) {
 }
 
 // Returns Docker version for this Kubelet.
-func (kl *Kubelet) GetDockerVersion() (string, error) {
+func (kl *Kubelet) GetDockerVersion() ([]uint, error) {
 	if kl.dockerClient == nil {
-		return "", fmt.Errorf("No Docker client")
+		return nil, fmt.Errorf("no Docker client")
 	}
-	env, err := kl.dockerClient.Version()
-	if err != nil {
-		return "", err
-	}
-	for _, entry := range *env {
-		if strings.HasPrefix(entry, "Version=") {
-			return strings.Split(entry, "=")[1], nil
-		}
-	}
-	return "", fmt.Errorf("Docker version unknown")
+	dockerRunner := dockertools.NewDockerContainerCommandRunner(kl.dockerClient)
+	return dockerRunner.GetDockerServerVersion()
 }
 
 // GetKubeletContainerLogs returns logs from the container

pkg/kubelet/kubelet_test.go

@@ -1367,6 +1367,10 @@ func (f *fakeContainerCommandRunner) RunInContainer(id string, cmd []string) ([]
 	return []byte{}, f.E
 }
 
+func (f *fakeContainerCommandRunner) GetDockerServerVersion() ([]uint, error) {
+	return nil, nil
+}
+
 func TestRunInContainerNoSuchPod(t *testing.T) {
 	fakeCommandRunner := fakeContainerCommandRunner{}
 	kubelet, fakeDocker := newTestKubelet(t)

pkg/kubelet/server.go

@@ -63,7 +63,7 @@ func ListenAndServeKubeletServer(host HostInterface, address net.IP, port uint,
 type HostInterface interface {
 	GetContainerInfo(podFullName string, uid types.UID, containerName string, req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
 	GetRootInfo(req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
-	GetDockerVersion() (string, error)
+	GetDockerVersion() ([]uint, error)
 	GetMachineInfo() (*info.MachineInfo, error)
 	GetBoundPods() ([]api.BoundPod, error)
 	GetPodByName(namespace, name string) (*api.BoundPod, bool)
@@ -109,16 +109,33 @@ func (s *Server) error(w http.ResponseWriter, err error) {
 	http.Error(w, fmt.Sprintf("Internal Error: %v", err), http.StatusInternalServerError)
 }
 
+func isValidDockerVersion(ver []uint) (bool, string) {
+	minAllowedVersion := []uint{1, 3, 0}
+	for i := 0; i < len(ver) && i < len(minAllowedVersion); i++ {
+		if ver[i] != minAllowedVersion[i] {
+			if ver[i] < minAllowedVersion[i] {
+				versions := make([]string, len(ver))
+				for i, v := range(ver) {
+					versions[i] = fmt.Sprint(v)
+				}
+				return false, strings.Join(versions, ".")
+			}
+			return true, ""
+		}
+	}
+	return true, ""
+}
+
 // handleHealthz handles /healthz request and checks Docker version
 func (s *Server) handleHealthz(w http.ResponseWriter, req *http.Request) {
-	version, err := s.host.GetDockerVersion()
+	versions, err := s.host.GetDockerVersion()
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
 		w.Write([]byte("unknown Docker version"))
 		return
 	}
-	const minDockerVersion = "1.3.0"
-	if version < minDockerVersion {
+	valid, version := isValidDockerVersion(versions)
+	if !valid {
 		w.WriteHeader(http.StatusInternalServerError)
 		msg := "Docker version is too old (" + version + ")"
 		w.Write([]byte(msg))

pkg/kubelet/server_test.go

@@ -42,7 +42,7 @@ type fakeKubelet struct {
 	boundPodsFunc     func() ([]api.BoundPod, error)
 	logFunc           func(w http.ResponseWriter, req *http.Request)
 	runFunc           func(podFullName string, uid types.UID, containerName string, cmd []string) ([]byte, error)
-	dockerVersionFunc func() (string, error)
+	dockerVersionFunc func() ([]uint, error)
 	containerLogsFunc func(podFullName, containerName, tail string, follow bool, stdout, stderr io.Writer) error
 }
 
@@ -62,7 +62,7 @@ func (fk *fakeKubelet) GetRootInfo(req *info.ContainerInfoRequest) (*info.Contai
 	return fk.rootInfoFunc(req)
 }
 
-func (fk *fakeKubelet) GetDockerVersion() (string, error) {
+func (fk *fakeKubelet) GetDockerVersion() ([]uint, error) {
 	return fk.dockerVersionFunc()
 }