func lookupPlugin(name, home string, opts []string, pg plugingetter.PluginGetter) (Driver, error) {
	pl, err := pg.Get(name, "GraphDriver", plugingetter.LOOKUP)
	if err != nil {
		return nil, fmt.Errorf("Error looking up graphdriver plugin %s: %v", name, err)
	}
	return newPluginDriver(name, home, opts, pl.Client())
}

func validateDriver(driver *api.Driver, pg plugingetter.PluginGetter, pluginType string) error {
	if driver == nil {
		// It is ok to not specify the driver. We will choose
		// a default driver.
		return nil
	}

	if driver.Name == "" {
		return grpc.Errorf(codes.InvalidArgument, "driver name: if driver is specified name is required")
	}

	if strings.ToLower(driver.Name) == networkallocator.DefaultDriver || strings.ToLower(driver.Name) == ipamapi.DefaultIPAM {
		return nil
	}

	p, err := pg.Get(driver.Name, pluginType, plugingetter.Lookup)
	if err != nil {
		return grpc.Errorf(codes.InvalidArgument, "error during lookup of plugin %s", driver.Name)
	}

	if p.IsV1() {
		return grpc.Errorf(codes.InvalidArgument, "legacy plugin %s of type %s is not supported in swarm mode", driver.Name, pluginType)
	}

	return nil
}

// validates that the plugins requested with the --authorization-plugin flag are valid AuthzDriver
// plugins present on the host and available to the daemon
func validateAuthzPlugins(requestedPlugins []string, pg plugingetter.PluginGetter) error {
	for _, reqPlugin := range requestedPlugins {
		if _, err := pg.Get(reqPlugin, authorization.AuthZApiImplements, plugingetter.LOOKUP); err != nil {
			return err
		}
	}
	return nil
}

func lookupPlugin(name string, pg plugingetter.PluginGetter, config Options) (Driver, error) {
	if !config.ExperimentalEnabled {
		return nil, fmt.Errorf("graphdriver plugins are only supported with experimental mode")
	}
	pl, err := pg.Get(name, "GraphDriver", plugingetter.Acquire)
	if err != nil {
		return nil, fmt.Errorf("Error looking up graphdriver plugin %s: %v", name, err)
	}
	return newPluginDriver(name, pl, config)
}