Add retries for SSH dial timeout

Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com>

ssh/client.go

@@ -2,12 +2,14 @@ package ssh
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 
 	"github.com/docker/docker/pkg/term"
+	"github.com/docker/machine/log"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -17,6 +19,10 @@ type Client struct {
 	Port     int
 }
 
+const (
+	maxDialAttempts = 10
+)
+
 func NewClient(user string, host string, port int, auth *Auth) (*Client, error) {
 	config, err := NewConfig(user, auth)
 	if err != nil {
@@ -58,16 +64,26 @@ func NewConfig(user string, auth *Auth) (*ssh.ClientConfig, error) {
 }
 
 func (client *Client) Run(command string) (Output, error) {
-	var output Output
+	var (
+		output Output
+		conn   *ssh.Client
+		err    error
+	)
 
-	conn, err := ssh.Dial("tcp", fmt.Sprintf("%s:%d", client.Hostname, client.Port), client.Config)
+	for i := 0; ; i++ {
-	if err != nil {
+		conn, err = ssh.Dial("tcp", fmt.Sprintf("%s:%d", client.Hostname, client.Port), client.Config)
-		return output, err
+		if err != nil {
+			log.Errorf("Error dialing TCP: %s", err)
+			if i == maxDialAttempts {
+				return output, errors.New("Max SSH/TCP dial attempts exceeded")
+			}
+		}
+		break
 	}
 
 	session, err := conn.NewSession()
 	if err != nil {
-		return output, err
+		return output, fmt.Errorf("Error getting new session: %s", err)
 	}
 
 	defer session.Close()