code: func (c *Client) ProvisionResource(req *ct.ResourceReq) (*ct.Resource, error) {
  	if req.ProviderID == "" {
  		return nil, errors.New("controller: missing provider id")
  	}
  	res := &ct.Resource{}
  	err := c.Post(fmt.Sprintf("/providers/%s/resources", req.ProviderID), req, res)
  	return res, err
  }
docs: // ProvisionResource uses a provider to provision a new resource for the
  // application. Returns details about the resource.