drivers/rackspace/client.go
func (c *Client) Authenticate(d *openstack.Driver) error {
	if c.Provider != nil {
		return nil
	}

	log.Debug("Authenticating to Rackspace.", map[string]string{
		"Username": d.Username,
	})

	apiKey := c.driver.APIKey
	opts := gophercloud.AuthOptions{
		Username: d.Username,
		APIKey:   apiKey,
	}

	provider, err := rackspace.NewClient(rackspace.RackspaceUSIdentity)
	if err != nil {
		return err
	}

	provider.UserAgent.Prepend(fmt.Sprintf("docker-machine/v%d", version.APIVersion))

	err = rackspace.Authenticate(provider, opts)
	if err != nil {
		return err
	}

	c.Provider = provider

	return nil
}
func (c *Client) Authenticate(d *openstack.Driver) error {
	if c.Provider != nil {
		return nil
	}

	log.Debug("Authenticating to Rackspace.", map[string]string{
		"Username": d.Username,
	})

	apiKey := c.driver.APIKey
	opts := gophercloud.AuthOptions{
		Username: d.Username,
		APIKey:   apiKey,
	}

	provider, err := rackspace.NewClient(rackspace.RackspaceUSIdentity)
	if err != nil {
		return err
	}

	provider.UserAgent.Prepend(fmt.Sprintf("docker-machine/v%d", version.APIVersion))

	err = rackspace.Authenticate(provider, opts)
	if err != nil {
		return err
	}

	c.Provider = provider

	return nil
}
// Authenticate creates a Rackspace-specific Gophercloud client.