Expose OpenStack driver's userdata param

This allows a user to pass a script or cloud-config file that can be
used to initialize the server before the server starts up. This
is particularly useful in enterprise cloud environments where the
available images on openstack might not be fully compatible with the
docker-machine provisioners.

Signed-off-by: Wade Tandy <wtandy@bloomberg.net>

drivers/openstack/client.go

@@ -63,6 +63,7 @@ func (c *GenericClient) CreateInstance(d *Driver) (string, error) {
 		Name:             d.MachineName,
 		FlavorRef:        d.FlavorId,
 		ImageRef:         d.ImageId,
+		UserData:         d.UserData,
 		SecurityGroups:   d.SecurityGroups,
 		AvailabilityZone: d.AvailabilityZone,
 	}

drivers/openstack/openstack.go

@@ -37,6 +37,7 @@ type Driver struct {
 	KeyPairName      string
 	NetworkName      string
 	NetworkId        string
+	UserData         []byte
 	PrivateKeyFile   string
 	SecurityGroups   []string
 	FloatingIpPool   string
@@ -161,6 +162,12 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 			Usage:  "Private keyfile to use for SSH (absolute path)",
 			Value:  "",
 		},
+		mcnflag.StringFlag{
+			EnvVar: "OS_USER_DATA_FILE",
+			Name:   "openstack-user-data-file",
+			Usage:  "File containing an openstack userdata script",
+			Value:  "",
+		},
 		mcnflag.StringFlag{
 			EnvVar: "OS_NETWORK_NAME",
 			Name:   "openstack-net-name",
@@ -270,6 +277,16 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	d.SSHPort = flags.Int("openstack-ssh-port")
 	d.KeyPairName = flags.String("openstack-keypair-name")
 	d.PrivateKeyFile = flags.String("openstack-private-key-file")
+
+	if flags.String("openstack-user-data-file") != "" {
+		userData, err := ioutil.ReadFile(flags.String("openstack-user-data-file"))
+		if err == nil {
+			d.UserData = userData
+		} else {
+			return err
+		}
+	}
+
 	d.SetSwarmConfigFromFlags(flags)
 
 	return d.checkConfig()