moby: Add system disk and disk size parameter to GCP

This makes gcp behave in a similar way to the qemu backend.
The minimum size on GCP 1GB, whereas qemu uses 256MB.
Without this, the LTP tests fail on GCP.

Signed-off-by: Dave Tucker <dt@docker.com>

src/cmd/moby/gcp.go

@@ -178,7 +178,7 @@ func (g GCPClient) DeleteImage(name string) error {
 }
 
 // CreateInstance creates and starts an instance on GCP
-func (g GCPClient) CreateInstance(name, image, zone, machineType string, replace bool) error {
+func (g GCPClient) CreateInstance(name, image, zone, machineType string, diskSize int, replace bool) error {
 	if replace {
 		if err := g.DeleteInstance(name, zone, true); err != nil {
 			return err
@@ -196,6 +196,15 @@ func (g GCPClient) CreateInstance(name, image, zone, machineType string, replace
 	sshKey := new(string)
 	*sshKey = fmt.Sprintf("moby:%s moby", string(ssh.MarshalAuthorizedKey(k)))
 
+	diskName := name + "-systemdisk"
+	diskOp, err := g.compute.Disks.Insert(g.projectName, zone, &compute.Disk{Name: diskName, SizeGb: int64(diskSize)}).Do()
+	if err != nil {
+		return err
+	}
+	if err := g.pollZoneOperationStatus(diskOp.Name, zone); err != nil {
+		return err
+	}
+
 	instanceObj := &compute.Instance{
 		MachineType: fmt.Sprintf("zones/%s/machineTypes/%s", zone, machineType),
 		Name:        name,
@@ -207,6 +216,11 @@ func (g GCPClient) CreateInstance(name, image, zone, machineType string, replace
 					SourceImage: fmt.Sprintf("global/images/%s", image),
 				},
 			},
+			{
+				AutoDelete: true,
+				Boot:       false,
+				Source:     fmt.Sprintf("zones/%s/disks/%s", zone, diskName),
+			},
 		},
 		NetworkInterfaces: []*compute.NetworkInterface{
 			{

src/cmd/moby/run_gcp.go

@@ -12,6 +12,7 @@ import (
 const (
 	defaultZone     = "europe-west1-d"
 	defaultMachine  = "g1-small"
+	defaultDiskSize = 1
 	zoneVar         = "MOBY_GCP_ZONE"
 	machineVar      = "MOBY_GCP_MACHINE"
 	keysVar         = "MOBY_GCP_KEYS"
@@ -20,6 +21,7 @@ const (
 	familyVar       = "MOBY_GCP_FAMILY"
 	publicVar       = "MOBY_GCP_PUBLIC"
 	nameVar         = "MOBY_GCP_IMAGE_NAME"
+	diskSizeVar     = "MOBY_GCP_DISK_SIZE"
 )
 
 // Process the run arguments and execute run
@@ -41,6 +43,8 @@ func runGcp(args []string) {
 	publicFlag := gcpCmd.Bool("public", false, "Select if file on GS should be public. *Optional* when 'prefix' is a filename")
 	familyFlag := gcpCmd.String("family", "", "GCP Image Family. A group of images where the family name points to the most recent image. *Optional* when 'prefix' is a filename")
 	nameFlag := gcpCmd.String("img-name", "", "Overrides the Name used to identify the file in Google Storage, Image and Instance. Defaults to [name]")
+	diskSizeFlag := gcpCmd.Int("disk-size", 0, "Size of system disk in GB")
+
 	if err := gcpCmd.Parse(args); err != nil {
 		log.Fatal("Unable to parse args")
 	}
@@ -61,6 +65,7 @@ func runGcp(args []string) {
 	public := getBoolValue(publicVar, *publicFlag)
 	family := getStringValue(familyVar, *familyFlag, "")
 	name := getStringValue(nameVar, *nameFlag, "")
+	diskSize := getIntValue(diskSizeVar, *diskSizeFlag, defaultDiskSize)
 
 	client, err := NewGCPClient(keys, project)
 	if err != nil {
@@ -93,7 +98,7 @@ func runGcp(args []string) {
 		name = prefix
 	}
 
-	if err = client.CreateInstance(name, prefix, zone, machine, true); err != nil {
+	if err = client.CreateInstance(name, prefix, zone, machine, diskSize, true); err != nil {
 		log.Fatal(err)
 	}
 

src/cmd/moby/util.go

@@ -1,6 +1,9 @@
 package main
 
-import "os"
+import (
+	"os"
+	"strconv"
+)
 
 func getStringValue(envKey string, flagVal string, defaultVal string) string {
 	var res string
@@ -23,6 +26,31 @@ func getStringValue(envKey string, flagVal string, defaultVal string) string {
 	return res
 }
 
+func getIntValue(envKey string, flagVal int, defaultVal int) int {
+	var res int
+
+	// If defined, take the env variable
+	if _, ok := os.LookupEnv(envKey); ok {
+		var err error
+		res, err = strconv.Atoi(os.Getenv(envKey))
+		if err != nil {
+			res = 0
+		}
+	}
+
+	// If a flag is specified, this value takes precedence
+	// Ignore cases where the flag carries the default value
+	if flagVal > 0 {
+		res = flagVal
+	}
+
+	// if we still don't have a value, use the default
+	if res == 0 {
+		res = defaultVal
+	}
+	return res
+}
+
 func getBoolValue(envKey string, flagVal bool) bool {
 	var res bool