etcd clientv3 election

election.go

	const prefix = "/resume-election/"

	cli, _ := clientv3.New(clientv3.Config{Endpoints: endpoints})
	defer cli.Close()

	var s *concurrency.Session
	s, _ = concurrency.NewSession(cli)
	defer s.Close()

	e := concurrency.NewElection(s, prefix)
        if err = e.Campaign(context.TODO(), "candidate1"); err != nil {
		t.Fatalf("Campaign() returned non nil err: %s", err)
	}

waitDeletes.go

// waitDeletes efficiently waits until all keys matching the prefix and no greater
// than the create revision.
func waitDeletes(ctx context.Context, client *v3.Client, pfx string, maxCreateRev int64) (*pb.ResponseHeader, error) {
	getOpts := append(v3.WithLastCreate(), v3.WithMaxCreateRev(maxCreateRev))
	for {
		resp, err := client.Get(ctx, pfx, getOpts...)
		if err != nil {
			return nil, err
		}
		if len(resp.Kvs) == 0 {
			return resp.Header, nil
		}
		lastKey := string(resp.Kvs[0].Key)
		if err = waitDelete(ctx, client, lastKey, resp.Header.Revision); err != nil {
			return nil, err
		}
	}
}