This adds a method to the Driver: PreCreateCheck. This can be used

where you want to run some prerequisite checks before attempting to
create
the machine.  In the case of EC2, this is a check for an existing
keypair.  This can be used in the other drivers in the future as well.

Signed-off-by: Evan Hazlett <ejhazlett@gmail.com>

commands_test.go

@@ -33,6 +33,10 @@ func (d *FakeDriver) GetState() (state.State, error) {
 	return d.MockState, nil
 }
 
+func (d *FakeDriver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *FakeDriver) Create() error {
 	return nil
 }

drivers/amazonec2/amazonec2.go

@@ -182,7 +182,28 @@ func (d *Driver) DriverName() string {
 	return driverName
 }
 
+func (d *Driver) checkPrereqs() error {
+	// check for existing keypair
+	key, err := d.getClient().GetKeyPair(d.MachineName)
+	if err != nil {
+		return err
+	}
+
+	if key != nil {
+		return fmt.Errorf("There is already a keypair with the name %s.  Please either remove that keypair or use a different machine name.", d.MachineName)
+	}
+	return nil
+}
+
+func (d *Driver) PreCreateCheck() error {
+	return d.checkPrereqs()
+}
+
 func (d *Driver) Create() error {
+	if err := d.checkPrereqs(); err != nil {
+		return err
+	}
+
 	log.Infof("Launching instance...")
 
 	if err := d.createKeyPair(); err != nil {

drivers/amazonec2/amz/describe_keypairs.go

@@ -0,0 +1,6 @@
+package amz
+
+type DescribeKeyPairsResponse struct {
+	RequestId string    `xml:"requestId"`
+	KeySet    []KeyPair `xml:"keySet>item"`
+}

drivers/amazonec2/amz/ec2.go

@@ -438,6 +438,42 @@ func (e *EC2) GetSubnets() ([]Subnet, error) {
 	return subnets, nil
 }
 
+func (e *EC2) GetKeyPairs() ([]KeyPair, error) {
+	keyPairs := []KeyPair{}
+	resp, err := e.performStandardAction("DescribeKeyPairs")
+	if err != nil {
+		return keyPairs, err
+	}
+	defer resp.Body.Close()
+	contents, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return keyPairs, fmt.Errorf("Error reading AWS response body: %s", err)
+	}
+
+	unmarshalledResponse := DescribeKeyPairsResponse{}
+	if err = xml.Unmarshal(contents, &unmarshalledResponse); err != nil {
+		return keyPairs, fmt.Errorf("Error unmarshalling AWS response XML: %s", err)
+	}
+
+	keyPairs = unmarshalledResponse.KeySet
+
+	return keyPairs, nil
+}
+
+func (e *EC2) GetKeyPair(name string) (*KeyPair, error) {
+	keyPairs, err := e.GetKeyPairs()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, key := range keyPairs {
+		if key.KeyName == name {
+			return &key, nil
+		}
+	}
+	return nil, nil
+}
+
 func (e *EC2) GetInstanceState(instanceId string) (state.State, error) {
 	resp, err := e.performInstanceAction(instanceId, "DescribeInstances", nil)
 	if err != nil {

drivers/amazonec2/amz/keypair.go

@@ -11,3 +11,8 @@ type ImportKeyPairResponse struct {
 	KeyFingerprint string `xml:"keyFingerprint"`
 	KeyMaterial    []byte `xml:"keyMaterial"`
 }
+
+type KeyPair struct {
+	KeyFingerprint string `xml:"keyFingerprint"`
+	KeyName        string `xml:"keyName"`
+}

drivers/azure/azure.go

@@ -171,6 +171,10 @@ func (driver *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	return nil
 }
 
+func (driver *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (driver *Driver) Create() error {
 	if err := driver.setUserSubscription(); err != nil {
 		return err

drivers/digitalocean/digitalocean.go

@@ -95,6 +95,10 @@ func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 	return nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 	log.Infof("Creating SSH key...")
 

drivers/drivers.go

@@ -32,6 +32,9 @@ type Driver interface {
 	// GetState returns the state that the host is in (running, stopped, etc)
 	GetState() (state.State, error)
 
+	// PreCreate allows for pre-create operations to make sure a driver is ready for creation
+	PreCreateCheck() error
+
 	// Create a host using the driver's config
 	Create() error
 

drivers/google/google.go

@@ -110,6 +110,10 @@ func (driver *Driver) initApis() (*ComputeUtil, error) {
 	return newComputeUtil(driver)
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 // Create creates a GCE VM instance acting as a docker host.
 func (driver *Driver) Create() error {
 	c, err := newComputeUtil(driver)

drivers/none/none.go

@@ -69,6 +69,10 @@ func (d *Driver) GetState() (state.State, error) {
 	return state.None, nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 	return nil
 }

drivers/openstack/openstack.go

@@ -312,6 +312,10 @@ func (d *Driver) GetState() (state.State, error) {
 	return state.None, nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 	d.KeyPairName = fmt.Sprintf("%s-%s", d.MachineName, utils.GenerateRandomID())
 

drivers/softlayer/driver.go

@@ -289,6 +289,10 @@ func (d *Driver) GetSSHCommand(args ...string) (*exec.Cmd, error) {
 	return ssh.GetSSHCommand(d.IPAddress, 22, "root", d.sshKeyPath(), args...), nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 	waitForStart := func() {
 		log.Infof("Waiting for host to become available")

drivers/virtualbox/virtualbox.go

@@ -112,6 +112,10 @@ func cpIso(src, dest string) error {
 	return nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 	var (
 		err    error

drivers/vmwarefusion/fusion.go

@@ -129,6 +129,10 @@ func (d *Driver) GetState() (state.State, error) {
 	return state.Stopped, nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 
 	var (

drivers/vmwarevcloudair/vcloudair.go

@@ -260,6 +260,10 @@ func (d *Driver) GetState() (state.State, error) {
 
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 func (d *Driver) Create() error {
 
 	key, err := d.createSSHKey()

drivers/vmwarevsphere/vsphere.go

@@ -215,6 +215,10 @@ func (d *Driver) GetState() (state.State, error) {
 	return state.None, nil
 }
 
+func (d *Driver) PreCreateCheck() error {
+	return nil
+}
+
 // the current implementation does the following:
 // 1. check whether the docker directory contains the boot2docker ISO
 // 2. generate an SSH keypair

store.go

@@ -31,7 +31,7 @@ func (s *Store) Create(name string, driverName string, flags drivers.DriverOptio
 		return nil, err
 	}
 	if exists {
-		return nil, fmt.Errorf("Host %q already exists", name)
+		return nil, fmt.Errorf("Machine %s already exists", name)
 	}
 
 	hostPath := filepath.Join(s.Path, name)
@@ -46,6 +46,10 @@ func (s *Store) Create(name string, driverName string, flags drivers.DriverOptio
 		}
 	}
 
+	if err := host.Driver.PreCreateCheck(); err != nil {
+		return nil, err
+	}
+
 	if err := os.MkdirAll(hostPath, 0700); err != nil {
 		return nil, err
 	}