exoscale: use StringSlice to specify security groups

This mean that the option has to be repeated to specify multiple
security groups.

Signed-off-by: Vincent Bernat <Vincent.Bernat@exoscale.ch>

drivers/amazonec2/amazonec2_test.go

@@ -35,6 +35,10 @@ func (d DriverOptionsMock) String(key string) string {
 	return d.Data[key].(string)
 }
 
+func (d DriverOptionsMock) StringSlice(key string) []string {
+	return d.Data[key].([]string)
+}
+
 func (d DriverOptionsMock) Int(key string) int {
 	return d.Data[key].(int)
 }

drivers/drivers.go

@@ -164,6 +164,7 @@ func GetDriverNames() []string {
 
 type DriverOptions interface {
 	String(key string) string
+	StringSlice(key string) []string
 	Int(key string) int
 	Bool(key string) bool
 }

drivers/exoscale/exoscale.go

@@ -84,10 +84,10 @@ func GetCreateFlags() []cli.Flag {
 			Value:  "ubuntu-14.04",
 			Usage:  "exoscale image template",
 		},
-		cli.StringFlag{
+		cli.StringSliceFlag{
 			EnvVar: "EXOSCALE_SECURITY_GROUP",
 			Name:   "exoscale-security-group",
-			Value:  "docker-machine",
+			Value:  &cli.StringSlice{},
 			Usage:  "exoscale security group",
 		},
 		cli.StringFlag{
@@ -142,8 +142,9 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	d.InstanceProfile = flags.String("exoscale-instance-profile")
 	d.DiskSize = flags.Int("exoscale-disk-size")
 	d.Image = flags.String("exoscale-image")
-	if flags.String("exoscale-security-group") != "" {
-		d.SecurityGroups = strings.Split(flags.String("exoscale-security-group"), ",")
+	d.SecurityGroups = flags.StringSlice("exoscale-security-group")
+	if len(d.SecurityGroups) == 0 {
+		d.SecurityGroups = []string{"docker-machine"}
 	}
 	d.AvailabilityZone = flags.String("exoscale-availability-zone")
 	d.SwarmMaster = flags.Bool("swarm-master")

drivers/softlayer/driver_test.go

@@ -26,6 +26,13 @@ func (d DriverOptionsMock) String(key string) string {
 	return ""
 }
 
+func (d DriverOptionsMock) StringSlice(key string) []string {
+	if value, ok := d.Data[key]; ok {
+		return value.([]string)
+	}
+	return []string{}
+}
+
 func (d DriverOptionsMock) Int(key string) int {
 	if value, ok := d.Data[key]; ok {
 		return value.(int)