2017-02-23 01:10:09 +03:00
|
|
|
// Copyright 2017 The etcd Authors
|
|
|
|
//
|
|
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
|
|
// you may not use this file except in compliance with the License.
|
|
|
|
// You may obtain a copy of the License at
|
|
|
|
//
|
|
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
//
|
|
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
|
|
// See the License for the specific language governing permissions and
|
|
|
|
// limitations under the License.
|
|
|
|
|
|
|
|
package grpcproxy
|
|
|
|
|
|
|
|
import (
|
2017-02-28 04:08:35 +03:00
|
|
|
"encoding/json"
|
|
|
|
"os"
|
|
|
|
|
2018-08-29 03:13:25 +03:00
|
|
|
"go.etcd.io/etcd/clientv3"
|
|
|
|
"go.etcd.io/etcd/clientv3/concurrency"
|
|
|
|
"go.etcd.io/etcd/clientv3/naming"
|
2017-02-23 01:10:09 +03:00
|
|
|
|
|
|
|
"golang.org/x/time/rate"
|
|
|
|
gnaming "google.golang.org/grpc/naming"
|
|
|
|
)
|
|
|
|
|
|
|
|
// allow maximum 1 retry per second
|
|
|
|
const registerRetryRate = 1
|
|
|
|
|
2017-02-28 04:08:35 +03:00
|
|
|
// Register registers itself as a grpc-proxy server by writing prefixed-key
|
2017-02-23 01:10:09 +03:00
|
|
|
// with session of specified TTL (in seconds). The returned channel is closed
|
|
|
|
// when the client's context is canceled.
|
2017-02-28 04:08:35 +03:00
|
|
|
func Register(c *clientv3.Client, prefix string, addr string, ttl int) <-chan struct{} {
|
2017-02-23 01:10:09 +03:00
|
|
|
rm := rate.NewLimiter(rate.Limit(registerRetryRate), registerRetryRate)
|
|
|
|
|
|
|
|
donec := make(chan struct{})
|
|
|
|
go func() {
|
|
|
|
defer close(donec)
|
|
|
|
|
|
|
|
for rm.Wait(c.Ctx()) == nil {
|
|
|
|
ss, err := registerSession(c, prefix, addr, ttl)
|
|
|
|
if err != nil {
|
|
|
|
plog.Warningf("failed to create a session %v", err)
|
|
|
|
continue
|
|
|
|
}
|
|
|
|
select {
|
|
|
|
case <-c.Ctx().Done():
|
|
|
|
ss.Close()
|
|
|
|
return
|
|
|
|
|
|
|
|
case <-ss.Done():
|
|
|
|
plog.Warning("session expired; possible network partition or server restart")
|
|
|
|
plog.Warning("creating a new session to rejoin")
|
|
|
|
continue
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}()
|
|
|
|
|
|
|
|
return donec
|
|
|
|
}
|
|
|
|
|
|
|
|
func registerSession(c *clientv3.Client, prefix string, addr string, ttl int) (*concurrency.Session, error) {
|
|
|
|
ss, err := concurrency.NewSession(c, concurrency.WithTTL(ttl))
|
|
|
|
if err != nil {
|
|
|
|
return nil, err
|
|
|
|
}
|
|
|
|
|
|
|
|
gr := &naming.GRPCResolver{Client: c}
|
2017-02-28 04:08:35 +03:00
|
|
|
if err = gr.Update(c.Ctx(), prefix, gnaming.Update{Op: gnaming.Add, Addr: addr, Metadata: getMeta()}, clientv3.WithLease(ss.Lease())); err != nil {
|
2017-02-23 01:10:09 +03:00
|
|
|
return nil, err
|
|
|
|
}
|
|
|
|
|
|
|
|
plog.Infof("registered %q with %d-second lease", addr, ttl)
|
|
|
|
return ss, nil
|
|
|
|
}
|
2017-02-28 04:08:35 +03:00
|
|
|
|
|
|
|
// meta represents metadata of proxy register.
|
|
|
|
type meta struct {
|
|
|
|
Name string `json:"name"`
|
|
|
|
}
|
|
|
|
|
|
|
|
func getMeta() string {
|
|
|
|
hostname, _ := os.Hostname()
|
|
|
|
bts, _ := json.Marshal(meta{Name: hostname})
|
|
|
|
return string(bts)
|
|
|
|
}
|
|
|
|
|
|
|
|
func decodeMeta(s string) (meta, error) {
|
|
|
|
m := meta{}
|
|
|
|
err := json.Unmarshal([]byte(s), &m)
|
|
|
|
return m, err
|
|
|
|
}
|