Validate and default Rackspace-specific options.

Signed-off-by: Ash Wilson <ash.wilson@rackspace.com>

drivers/rackspace/rackspace.go

@@ -1,6 +1,7 @@
 package rackspace
 
 import (
+	"fmt"
 	"os"
 
 	log "github.com/Sirupsen/logrus"
@@ -11,7 +12,7 @@ import (
 
 // Driver is a machine driver for Rackspace. It's a specialization of the generic OpenStack one.
 type Driver struct {
-	drivers.Driver
+	*openstack.Driver
 
 	APIKey string
 }
@@ -55,9 +56,13 @@ func RegisterCreateFlags(cmd *flag.FlagSet) interface{} {
 		os.Getenv("OS_REGION_NAME"),
 		"Rackspace region name",
 	)
+	endpointDefault := os.Getenv("OS_ENDPOINT_TYPE")
+	if endpointDefault == "" {
+		endpointDefault = "publicURL"
+	}
 	createFlags.EndpointType = cmd.String(
 		[]string{"-rackspace-endpoint-type"},
-		os.Getenv("OS_ENDPOINT_TYPE"),
+		endpointDefault,
 		"Rackspace endpoint type (adminURL, internalURL or the default publicURL)",
 	)
 	createFlags.ImageID = cmd.String(
@@ -99,3 +104,56 @@ func NewDriver(storePath string) (drivers.Driver, error) {
 	client.driver = driver
 	return driver, nil
 }
+
+// DriverName is the user-visible name of this driver.
+func (d *Driver) DriverName() string {
+	return "rackspace"
+}
+
+// SetConfigFromFlags assigns and verifies the command-line arguments presented to the driver.
+func (d *Driver) SetConfigFromFlags(flagsInterface interface{}) error {
+	flags := flagsInterface.(*CreateFlags)
+
+	d.Username = *flags.Username
+	d.APIKey = *flags.APIKey
+	d.Region = *flags.Region
+	d.MachineName = *flags.MachineName
+	d.EndpointType = *flags.EndpointType
+	d.ImageId = *flags.ImageID
+	d.FlavorId = *flags.FlavorID
+	d.SSHUser = *flags.SSHUser
+	d.SSHPort = *flags.SSHPort
+
+	return d.checkConfig()
+}
+
+func missingEnvOrOption(setting, envVar, opt string) error {
+	return fmt.Errorf(
+		"%s must be specified either using the environment variable %s or the CLI option %s",
+		setting,
+		envVar,
+		opt,
+	)
+}
+
+func (d *Driver) checkConfig() error {
+	if d.Username == "" {
+		return missingEnvOrOption("Username", "OS_USERNAME", "--rackspace-username")
+	}
+	if d.APIKey == "" {
+		return missingEnvOrOption("API key", "OS_API_KEY", "--rackspace-api-key")
+	}
+
+	if d.ImageId == "" {
+		// Default to the Ubuntu 14.10 image.
+		// This is done here, rather than in the option registration, to keep the default value
+		// from making "machine create --help" ugly.
+		d.ImageId = "0766e5df-d60a-4100-ae8c-07f27ec0148f"
+	}
+
+	if d.EndpointType != "publicURL" && d.EndpointType != "adminURL" && d.EndpointType != "internalURL" {
+		return fmt.Errorf(`Invalid endpoint type "%s". Endpoint type must be publicURL, adminURL or internalURL.`, d.EndpointType)
+	}
+
+	return nil
+}