etcdmain/etcd.go
func startEtcd(cfg *embed.Config) (<-chan struct{}, <-chan error, error) {
	e, err := embed.StartEtcd(cfg)
	if err != nil {
		return nil, nil, err
	}
	osutil.RegisterInterruptHandler(e.Close)
	select {
	case <-e.Server.ReadyNotify(): // wait for e.Server to join the cluster
	case <-e.Server.StopNotify(): // publish aborted from 'ErrStopped'
	}
	return e.Server.StopNotify(), e.Err(), nil
}
func startEtcd(cfg *embed.Config) (<-chan struct{}, <-chan error, error) {
	e, err := embed.StartEtcd(cfg)
	if err != nil {
		return nil, nil, err
	}
	osutil.RegisterInterruptHandler(e.Close)
	select {
	case <-e.Server.ReadyNotify(): // wait for e.Server to join the cluster
	case <-e.Server.StopNotify(): // publish aborted from 'ErrStopped'
	}
	return e.Server.StopNotify(), e.Err(), nil
}
// startEtcd runs StartEtcd in addition to hooks needed for standalone etcd.