Merge pull request #2752 from dgageot/google-reuse

Support creating a machine from an existing google VM

docs/drivers/gce.md

@@ -50,6 +50,7 @@ To create a machine instance, specify `--driver google`, the project id and the
     -   `--google-preemptible`: Instance preemptibility.
     -   `--google-tags`: Instance tags (comma-separated).
     -   `--google-use-internal-ip`: When this option is used during create it will make docker-machine use internal rather than public NATed IPs. The flag is persistent in the sense that a machine created with it retains the IP. It's useful for managing docker machines from another machine on the same network e.g. while deploying swarm.
+    -   `--google-use-existing`: Don't create a new VM, use an existing one. This is useful when you'd like to provision Docker on a VM you created yourself, maybe because it uses create options not supported by this driver. 
 
 The GCE driver will use the `ubuntu-1510-wily-v20151114` instance image unless otherwise specified. To obtain a
 list of image URLs run:
@@ -72,3 +73,4 @@ Environment variables and default values:
 | `--google-preemptible`     | `GOOGLE_PREEMPTIBLE`     | -                                    |
 | `--google-tags`            | `GOOGLE_TAGS`            | -                                    |
 | `--google-use-internal-ip` | `GOOGLE_USE_INTERNAL_IP` | -                                    |
+| `--google-use-existing`    | `GOOGLE_USE_EXISTING`    | -                                    |

drivers/google/compute_util.go

@@ -88,6 +88,11 @@ func (c *ComputeUtil) disk() (*raw.Disk, error) {
 
 // deleteDisk deletes the persistent disk.
 func (c *ComputeUtil) deleteDisk() error {
+	disk, _ := c.disk()
+	if disk == nil {
+		return nil
+	}
+
 	log.Infof("Deleting disk.")
 	op, err := c.service.Disks.Delete(c.project, c.zone, c.diskName()).Do()
 	if err != nil {
@@ -162,8 +167,9 @@ func (c *ComputeUtil) portsUsed() ([]string, error) {
 	return ports, nil
 }
 
-func (c *ComputeUtil) createFirewallRule() error {
+// openFirewallPorts configures the firewall to open docker and swarm ports.
-	log.Infof("Opening firewall ports.")
+func (c *ComputeUtil) openFirewallPorts() error {
+	log.Infof("Opening firewall ports")
 
 	create := false
 	rule, _ := c.firewallRule()
@@ -213,11 +219,7 @@ func (c *ComputeUtil) instance() (*raw.Instance, error) {
 
 // createInstance creates a GCE VM instance.
 func (c *ComputeUtil) createInstance(d *Driver) error {
-	log.Infof("Creating instance.")
+	log.Infof("Creating instance")
-
-	if err := c.createFirewallRule(); err != nil {
-		return err
-	}
 
 	instance := &raw.Instance{
 		Name:        c.instanceName,
@@ -280,7 +282,7 @@ func (c *ComputeUtil) createInstance(d *Driver) error {
 		return err
 	}
 
-	log.Infof("Waiting for Instance...")
+	log.Infof("Waiting for Instance")
 	if err = c.waitForRegionalOp(op.Name); err != nil {
 		return err
 	}
@@ -290,15 +292,58 @@ func (c *ComputeUtil) createInstance(d *Driver) error {
 		return err
 	}
 
-	// Update the SSH Key
+	return c.uploadSSHKey(instance, d.GetSSHKeyPath())
-	sshKey, err := ioutil.ReadFile(d.GetSSHKeyPath() + ".pub")
+}
+
+// configureInstance configures an existing instance for use with Docker Machine.
+func (c *ComputeUtil) configureInstance(d *Driver) error {
+	log.Infof("Configuring instance")
+
+	instance, err := c.instance()
 	if err != nil {
 		return err
 	}
 
+	if err := c.addFirewallTag(instance); err != nil {
+		return err
+	}
+
+	return c.uploadSSHKey(instance, d.GetSSHKeyPath())
+}
+
+// addFirewallTag adds a tag to the instance to match the firewall rule.
+func (c *ComputeUtil) addFirewallTag(instance *raw.Instance) error {
+	log.Infof("Adding tag for the firewall rule")
+
+	tags := instance.Tags
+	for _, tag := range tags.Items {
+		if tag == firewallTargetTag {
+			return nil
+		}
+	}
+
+	tags.Items = append(tags.Items, firewallTargetTag)
+
+	op, err := c.service.Instances.SetTags(c.project, c.zone, instance.Name, tags).Do()
+	if err != nil {
+		return err
+	}
+
+	return c.waitForRegionalOp(op.Name)
+}
+
+// uploadSSHKey updates the instance metadata with the given ssh key.
+func (c *ComputeUtil) uploadSSHKey(instance *raw.Instance, sshKeyPath string) error {
 	log.Infof("Uploading SSH Key")
+
+	sshKey, err := ioutil.ReadFile(sshKeyPath + ".pub")
+	if err != nil {
+		return err
+	}
+
 	metaDataValue := fmt.Sprintf("%s:%s %s\n", c.userName, strings.TrimSpace(string(sshKey)), c.userName)
-	op, err = c.service.Instances.SetMetadata(c.project, c.zone, c.instanceName, &raw.Metadata{
+
+	op, err := c.service.Instances.SetMetadata(c.project, c.zone, c.instanceName, &raw.Metadata{
 		Fingerprint: instance.Metadata.Fingerprint,
 		Items: []*raw.MetadataItems{
 			{
@@ -307,10 +352,6 @@ func (c *ComputeUtil) createInstance(d *Driver) error {
 			},
 		},
 	}).Do()
-	if err != nil {
-		return err
-	}
-	log.Infof("Waiting for SSH Key")
 
 	return c.waitForRegionalOp(op.Name)
 }
@@ -360,6 +401,7 @@ func (c *ComputeUtil) startInstance() error {
 	return c.waitForRegionalOp(op.Name)
 }
 
+// waitForOp waits for the operation to finish.
 func (c *ComputeUtil) waitForOp(opGetter func() (*raw.Operation, error)) error {
 	for {
 		op, err := opGetter()
@@ -367,7 +409,7 @@ func (c *ComputeUtil) waitForOp(opGetter func() (*raw.Operation, error)) error {
 			return err
 		}
 
-		log.Debugf("operation %q status: %s", op.Name, op.Status)
+		log.Debugf("Operation %q status: %s", op.Name, op.Status)
 		if op.Status == "DONE" {
 			if op.Error != nil {
 				return fmt.Errorf("Operation error: %v", *op.Error.Errors[0])
@@ -379,7 +421,7 @@ func (c *ComputeUtil) waitForOp(opGetter func() (*raw.Operation, error)) error {
 	return nil
 }
 
-// waitForOp waits for the operation to finish.
+// waitForRegionalOp waits for the regional operation to finish.
 func (c *ComputeUtil) waitForRegionalOp(name string) error {
 	return c.waitForOp(func() (*raw.Operation, error) {
 		return c.service.ZoneOperations.Get(c.project, c.zone, name).Do()

drivers/google/google.go

@@ -26,6 +26,7 @@ type Driver struct {
 	DiskSize      int
 	Project       string
 	Tags          string
+	UseExisting   bool
 }
 
 const (
@@ -110,6 +111,11 @@ func (d *Driver) GetCreateFlags() []mcnflag.Flag {
 			Usage:  "Use internal GCE Instance IP rather than public one",
 			EnvVar: "GOOGLE_USE_INTERNAL_IP",
 		},
+		mcnflag.BoolFlag{
+			Name:   "google-use-existing",
+			Usage:  "Don't create a new VM, use an existing one",
+			EnvVar: "GOOGLE_USE_EXISTING",
+		},
 	}
 }
 
@@ -156,6 +162,8 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	}
 
 	d.Zone = flags.String("google-zone")
+	d.UseExisting = flags.Bool("google-use-existing")
+	if !d.UseExisting {
 		d.MachineType = flags.String("google-machine-type")
 		d.MachineImage = flags.String("google-machine-image")
 		d.DiskSize = flags.Int("google-disk-size")
@@ -165,6 +173,7 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 		d.UseInternalIP = flags.Bool("google-use-internal-ip")
 		d.Scopes = flags.String("google-scopes")
 		d.Tags = flags.String("google-tags")
+	}
 	d.SSHUser = flags.String("google-username")
 	d.SSHPort = 22
 	d.SetSwarmConfigFromFlags(flags)
@@ -191,8 +200,15 @@ func (d *Driver) PreCreateCheck() error {
 	// doesn't exist, so just check instance for nil.
 	log.Infof("Check if the instance already exists")
 
-	if instance, _ := c.instance(); instance != nil {
+	instance, _ := c.instance()
-		return fmt.Errorf("Instance %v already exists.", d.MachineName)
+	if d.UseExisting {
+		if instance == nil {
+			return fmt.Errorf("Unable to find instance %q in zone %q.", d.MachineName, d.Zone)
+		}
+	} else {
+		if instance != nil {
+			return fmt.Errorf("Instance %q already exists in zone %q.", d.MachineName, d.Zone)
+		}
 	}
 
 	return nil
@@ -213,6 +229,13 @@ func (d *Driver) Create() error {
 		return err
 	}
 
+	if err := c.openFirewallPorts(); err != nil {
+		return err
+	}
+
+	if d.UseExisting {
+		return c.configureInstance(d)
+	}
 	return c.createInstance(d)
 }