Add host connectivity and Docker version check

cluster/hosts.go

@@ -12,18 +12,18 @@ import (
 func (c *Cluster) TunnelHosts() error {
 	for i := range c.EtcdHosts {
 		if err := c.EtcdHosts[i].TunnelUp(); err != nil {
-			return fmt.Errorf("Failed to set up SSH tunneling for Etcd hosts: %v", err)
+			return fmt.Errorf("Failed to set up SSH tunneling for Etcd host [%s]: %v", c.EtcdHosts[i].Address, err)
 		}
 	}
 	for i := range c.ControlPlaneHosts {
 		err := c.ControlPlaneHosts[i].TunnelUp()
 		if err != nil {
-			return fmt.Errorf("Failed to set up SSH tunneling for Control hosts: %v", err)
+			return fmt.Errorf("Failed to set up SSH tunneling for Control host [%s]: %v", c.ControlPlaneHosts[i].Address, err)
 		}
 	}
 	for i := range c.WorkerHosts {
 		if err := c.WorkerHosts[i].TunnelUp(); err != nil {
-			return fmt.Errorf("Failed to set up SSH tunneling for Worker hosts: %v", err)
+			return fmt.Errorf("Failed to set up SSH tunneling for Worker host [%s]: %v", c.WorkerHosts[i].Address, err)
 		}
 	}
 	return nil

cluster/validation.go

@@ -35,10 +35,7 @@ func (c *Cluster) ValidateCluster() error {
 	}
 
 	// validate services options
-	if err := validateServicesOptions(c); err != nil {
-		return err
-	}
-	return nil
+	return validateServicesOptions(c)
 }
 
 func validateAuthOptions(c *Cluster) error {

docker/docker.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"os"
 	"reflect"
+	"regexp"
 
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/container"
@@ -14,6 +15,10 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+var K8sDockerVersions = map[string][]string{
+	"1.8": {"1.12.6", "1.13.1", "17.03.2"},
+}
+
 func DoRunContainer(dClient *client.Client, imageCfg *container.Config, hostCfg *container.HostConfig, containerName string, hostname string, plane string) error {
 	isRunning, err := IsContainerRunning(dClient, hostname, containerName)
 	if err != nil {
@@ -225,3 +230,15 @@ func IsContainerUpgradable(dClient *client.Client, imageCfg *container.Config, c
 	logrus.Debugf("[%s] Container [%s] is not eligible for updgrade on host [%s]", plane, containerName, hostname)
 	return false, nil
 }
+
+func IsSupportedDockerVersion(info types.Info, K8sVersion string) (bool, error) {
+	// Docker versions are not semver compliant since stable/edge version (17.03 and higher) so we need to check if the reported ServerVersion starts with a compatible version
+	for _, DockerVersion := range K8sDockerVersions[K8sVersion] {
+		DockerVersionRegexp := regexp.MustCompile("^" + DockerVersion)
+		if DockerVersionRegexp.MatchString(info.ServerVersion) {
+			return true, nil
+		}
+
+	}
+	return false, nil
+}

hosts/dialer.go

@@ -11,9 +11,11 @@ import (
 	"syscall"
 
 	"github.com/docker/docker/client"
+	"github.com/rancher/rke/docker"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/crypto/ssh"
 	"golang.org/x/crypto/ssh/terminal"
+	"golang.org/x/net/context"
 )
 
 type dialer struct {
@@ -23,6 +25,7 @@ type dialer struct {
 
 const (
 	DockerAPIVersion = "1.24"
+	K8sVersion       = "1.8"
 )
 
 func (d *dialer) Dial(network, addr string) (net.Conn, error) {
@@ -35,24 +38,25 @@ func (d *dialer) Dial(network, addr string) (net.Conn, error) {
 	// Establish connection with SSH server
 	conn, err := ssh.Dial("tcp", sshAddr, cfg)
 	if err != nil {
-		return nil, fmt.Errorf("Error establishing SSH connection: %v", err)
+		return nil, fmt.Errorf("Failed to dial ssh using address [%s]: %v", sshAddr, err)
 	}
 	if len(d.host.DockerSocket) == 0 {
 		d.host.DockerSocket = "/var/run/docker.sock"
 	}
 	remote, err := conn.Dial("unix", d.host.DockerSocket)
 	if err != nil {
-		return nil, fmt.Errorf("Error connecting to Docker socket on host [%s]: %v", d.host.Address, err)
+		return nil, fmt.Errorf("Failed to dial to Docker socket: %v", err)
 	}
 	return remote, err
 }
 
 func (h *Host) TunnelUp() error {
-	logrus.Infof("[ssh] Start tunnel for host [%s]", h.Address)
+	logrus.Infof("[ssh] Setup tunnel for host [%s]", h.Address)
 	key, err := checkEncryptedKey(h.SSHKey, h.SSHKeyPath)
 	if err != nil {
 		return fmt.Errorf("Failed to parse the private key: %v", err)
 	}
+
 	dialer := &dialer{
 		host:   h,
 		signer: key,
@@ -67,8 +71,22 @@ func (h *Host) TunnelUp() error {
 	logrus.Debugf("Connecting to Docker API for host [%s]", h.Address)
 	h.DClient, err = client.NewClient("unix:///var/run/docker.sock", DockerAPIVersion, httpClient, nil)
 	if err != nil {
-		return fmt.Errorf("Can't connect to Docker for host [%s]: %v", h.Address, err)
+		return fmt.Errorf("Can't initiate NewClient: %v", err)
 	}
+	info, err := h.DClient.Info(context.Background())
+	if err != nil {
+		return fmt.Errorf("Can't retrieve Docker Info: %v", err)
+	}
+	logrus.Debugf("Docker Info found: %#v", info)
+	isvalid, err := docker.IsSupportedDockerVersion(info, K8sVersion)
+	if err != nil {
+		return fmt.Errorf("Error while determining supported Docker version [%s]: %v", info.ServerVersion, err)
+	}
+
+	if !isvalid {
+		return fmt.Errorf("Unsupported Docker version found [%s], supported versions are %v", info.ServerVersion, docker.K8sDockerVersions[K8sVersion])
+	}
+
 	return nil
 }