Merge pull request #4117 from wojtek-t/validate_docker_version

Check Docker version in Kubelet /healthz handler

pkg/kubelet/dockertools/docker.go

@@ -25,6 +25,7 @@ import (
 	"io"
 	"io/ioutil"
 	"math/rand"
+	"os"
 	"os/exec"
 	"strconv"
 	"strings"
@@ -104,7 +105,7 @@ 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 +128,7 @@ 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
 	}
@@ -641,6 +642,35 @@ func parseImageName(image string) (string, string) {
 	return image, tag
 }
 
+// Get a docker endpoint, either from the string passed in, or $DOCKER_HOST environment variables
+func getDockerEndpoint(dockerEndpoint string) string {
+	var endpoint string
+	if len(dockerEndpoint) > 0 {
+		endpoint = dockerEndpoint
+	} else if len(os.Getenv("DOCKER_HOST")) > 0 {
+		endpoint = os.Getenv("DOCKER_HOST")
+	} else {
+		endpoint = "unix:///var/run/docker.sock"
+	}
+	glog.Infof("Connecting to docker on %s", endpoint)
+
+	return endpoint
+}
+
+func ConnectToDockerOrDie(dockerEndpoint string) DockerInterface {
+	if dockerEndpoint == "fake://" {
+		return &FakeDockerClient{
+			VersionInfo: []string{"apiVersion=1.16"},
+		}
+	}
+	client, err := docker.NewClient(getDockerEndpoint(dockerEndpoint))
+	if err != nil {
+		glog.Fatal("Couldn't connect to docker.")
+	}
+	return client
+}
+
 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)
 	}