Fixes #1243 Custom GCE images support

Signed-off-by: Andrew Grande <aprepel@gmail.com>

Signed-off-by: David Gageot <david@gageot.net>

docs/drivers/gce.md

@@ -43,6 +43,7 @@ $ docker-machine create --driver google \
 - `--google-project`: **required** The id of your project to use when launching the instance.
  - `--google-zone`: The zone to launch the instance.
  - `--google-machine-type`: The type of instance.
+ - `--google-machine-image`: The absolute URL to a base VM image to instantiate.
  - `--google-username`: The username to use for the instance.
  - `--google-scopes`: The scopes for OAuth 2.0 to Access Google APIs. See [Google Compute Engine Doc](https://cloud.google.com/storage/docs/authentication).
  - `--google-disk-size`: The disk size of instance.
@@ -51,7 +52,11 @@ $ docker-machine create --driver google \
  - `--google-preemptible`: Instance preemptibility.
  - `--google-tags`: Instance tags (comma-separated).
 
-The driver uses the `ubuntu-1404-trusty-v20150909a` disk image.
+The GCE driver will use the `ubuntu-1404-trusty-v20150909a` instance image unless otherwise specified. To obtain a
+list of image URLs run:
+```
+gcloud compute images list --uri
+```
 
 Environment variables and default values:
 
@@ -60,6 +65,7 @@ Environment variables and default values:
 | **`--google-project`**    | `GOOGLE_PROJECT`      | -                                    |
 | `--google-zone`           | `GOOGLE_ZONE`         | `us-central1-a`                      |
 | `--google-machine-type`   | `GOOGLE_MACHINE_TYPE` | `n1-standard-1`                      |
+| `--google-machine-image`  | `GOOGLE_MACHINE_IMAGE`| `ubuntu-1404-trusty-v20150909a`      |
 | `--google-username`       | `GOOGLE_USERNAME`     | `docker-user`                        |
 | `--google-scopes`         | `GOOGLE_SCOPES`       | `devstorage.read_only,logging.write` |
 | `--google-disk-size`      | `GOOGLE_DISK_SIZE`    | `10`                                 |

drivers/google/compute_util.go

@@ -35,7 +35,6 @@ type ComputeUtil struct {
 
 const (
 	apiURL             = "https://www.googleapis.com/compute/v1/projects/"
-	imageName          = "https://www.googleapis.com/compute/v1/projects/ubuntu-os-cloud/global/images/ubuntu-1404-trusty-v20150909a"
 	firewallRule       = "docker-machines"
 	port               = "2376"
 	firewallTargetTag  = "docker-machine"
@@ -231,7 +230,7 @@ func (c *ComputeUtil) createInstance(d *Driver) error {
 	if disk == nil || err != nil {
 		instance.Disks[0].InitializeParams = &raw.AttachedDiskInitializeParams{
 			DiskName:    c.diskName(),
-			SourceImage: imageName,
+			SourceImage: d.MachineImage,
 			// The maximum supported disk size is 1000GB, the cast should be fine.
 			DiskSizeGb: int64(d.DiskSize),
 			DiskType:   c.diskType(),

drivers/google/google.go

@@ -14,21 +14,23 @@ import (
 // Driver is a struct compatible with the docker.hosts.drivers.Driver interface.
 type Driver struct {
 	*drivers.BaseDriver
-	Zone        string
+	Zone         string
-	MachineType string
+	MachineType  string
-	DiskType    string
+	MachineImage string
-	Address     string
+	DiskType     string
-	Preemptible bool
+	Address      string
-	Scopes      string
+	Preemptible  bool
-	DiskSize    int
+	Scopes       string
-	Project     string
+	DiskSize     int
-	Tags        string
+	Project      string
+	Tags         string
 }
 
 const (
 	defaultZone        = "us-central1-a"
 	defaultUser        = "docker-user"
 	defaultMachineType = "n1-standard-1"
+	defaultImageName   = "https://www.googleapis.com/compute/v1/projects/ubuntu-os-cloud/global/images/ubuntu-1404-trusty-v20150909a"
 	defaultScopes      = "https://www.googleapis.com/auth/devstorage.read_only,https://www.googleapis.com/auth/logging.write"
 	defaultDiskType    = "pd-standard"
 	defaultDiskSize    = 10
@@ -50,6 +52,12 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 			Value:  defaultMachineType,
 			EnvVar: "GOOGLE_MACHINE_TYPE",
 		},
+		mcnflag.StringFlag{
+			Name:   "google-machine-image",
+			Usage:  "GCE Machine Image Absolute URL",
+			Value:  defaultImageName,
+			EnvVar: "GOOGLE_MACHINE_IMAGE",
+		},
 		mcnflag.StringFlag{
 			Name:   "google-username",
 			Usage:  "GCE User Name",
@@ -101,11 +109,12 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 // NewDriver creates a Driver with the specified storePath.
 func NewDriver(machineName string, storePath string) *Driver {
 	return &Driver{
-		Zone:        defaultZone,
+		Zone:         defaultZone,
-		DiskType:    defaultDiskType,
+		DiskType:     defaultDiskType,
-		DiskSize:    defaultDiskSize,
+		DiskSize:     defaultDiskSize,
-		MachineType: defaultMachineType,
+		MachineType:  defaultMachineType,
-		Scopes:      defaultScopes,
+		MachineImage: defaultImageName,
+		Scopes:       defaultScopes,
 		BaseDriver: &drivers.BaseDriver{
 			SSHUser:     defaultUser,
 			MachineName: machineName,
@@ -141,6 +150,7 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 
 	d.Zone = flags.String("google-zone")
 	d.MachineType = flags.String("google-machine-type")
+	d.MachineImage = flags.String("google-machine-image")
 	d.DiskSize = flags.Int("google-disk-size")
 	d.DiskType = flags.String("google-disk-type")
 	d.Address = flags.String("google-address")