Adds virtualbox-cpu-count - fixes #819

Signed-off-by: Paul Biggar <paul.biggar@gmail.com>

docs/index.md

@@ -823,6 +823,7 @@ Options:
  - `--virtualbox-boot2docker-url`: The URL of the boot2docker image. Defaults to the latest available version.
  - `--virtualbox-disk-size`: Size of disk for the host in MB. Default: `20000`
  - `--virtualbox-memory`: Size of memory for the host in MB. Default: `1024`
+ - `--virtualbox-cpu-count`: Number of CPUs to use to create the VM. Defaults to number of available CPUs.
 
 The VirtualBox driver uses the latest boot2docker image.
 

drivers/virtualbox/virtualbox.go

@@ -31,6 +31,7 @@ const (
 )
 
 type Driver struct {
+	CPU            int
 	MachineName    string
 	SSHUser        string
 	SSHPort        int
@@ -46,6 +47,7 @@ type Driver struct {
 }
 
 type CreateFlags struct {
+	CPU            *int
 	Memory         *int
 	DiskSize       *int
 	Boot2DockerURL *string
@@ -67,6 +69,12 @@ func GetCreateFlags() []cli.Flag {
 			Usage: "Size of memory for host in MB",
 			Value: 1024,
 		},
+		cli.IntFlag{
+			Name:   "virtualbox-cpu-count",
+			Usage:  "number of CPUs for the machine (-1 to use the number of CPUs available)",
+			EnvVar: "VIRTUALBOX_CPU_COUNT",
+			Value:  -1,
+		},
 		cli.IntFlag{
 			Name:  "virtualbox-disk-size",
 			Usage: "Size of disk for host in MB",
@@ -137,6 +145,7 @@ func (d *Driver) GetURL() (string, error) {
 }
 
 func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
+	d.CPU = flags.Int("virtualbox-cpu-count")
 	d.Memory = flags.Int("virtualbox-memory")
 	d.DiskSize = flags.Int("virtualbox-disk-size")
 	d.Boot2DockerURL = flags.String("virtualbox-boot2docker-url")
@@ -225,7 +234,10 @@ func (d *Driver) Create() error {
 		return err
 	}
 
-	cpus := uint(runtime.NumCPU())
+	cpus := d.CPU
+	if cpus < 1 {
+		cpus = int(runtime.NumCPU())
+	}
 	if cpus > 32 {
 		cpus = 32
 	}