blob: 913cd28255b285e43da4da0237f4f0733d876a94 [file] [log] [blame]
Girish Gowdra64503432020-01-07 10:59:10 +05301// Copyright 2016 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// Package clientv3 implements the official Go etcd client for v3.
16//
17// Create client using `clientv3.New`:
18//
19// // expect dial time-out on ipv4 blackhole
20// _, err := clientv3.New(clientv3.Config{
21// Endpoints: []string{"http://254.0.0.1:12345"},
22// DialTimeout: 2 * time.Second,
23// })
24//
25// // etcd clientv3 >= v3.2.10, grpc/grpc-go >= v1.7.3
26// if err == context.DeadlineExceeded {
27// // handle errors
28// }
29//
30// // etcd clientv3 <= v3.2.9, grpc/grpc-go <= v1.2.1
31// if err == grpc.ErrClientConnTimeout {
32// // handle errors
33// }
34//
35// cli, err := clientv3.New(clientv3.Config{
36// Endpoints: []string{"localhost:2379", "localhost:22379", "localhost:32379"},
37// DialTimeout: 5 * time.Second,
38// })
39// if err != nil {
40// // handle error!
41// }
42// defer cli.Close()
43//
44// Make sure to close the client after using it. If the client is not closed, the
45// connection will have leaky goroutines.
46//
47// To specify a client request timeout, wrap the context with context.WithTimeout:
48//
49// ctx, cancel := context.WithTimeout(context.Background(), timeout)
50// resp, err := kvc.Put(ctx, "sample_key", "sample_value")
51// cancel()
52// if err != nil {
53// // handle error!
54// }
55// // use the response
56//
57// The Client has internal state (watchers and leases), so Clients should be reused instead of created as needed.
58// Clients are safe for concurrent use by multiple goroutines.
59//
60// etcd client returns 3 types of errors:
61//
62// 1. context error: canceled or deadline exceeded.
63// 2. gRPC status error: e.g. when clock drifts in server-side before client's context deadline exceeded.
64// 3. gRPC error: see https://github.com/etcd-io/etcd/blob/master/etcdserver/api/v3rpc/rpctypes/error.go
65//
66// Here is the example code to handle client errors:
67//
68// resp, err := kvc.Put(ctx, "", "")
69// if err != nil {
70// if err == context.Canceled {
71// // ctx is canceled by another routine
72// } else if err == context.DeadlineExceeded {
73// // ctx is attached with a deadline and it exceeded
74// } else if err == rpctypes.ErrEmptyKey {
75// // client-side error: key is not provided
76// } else if ev, ok := status.FromError(err); ok {
77// code := ev.Code()
78// if code == codes.DeadlineExceeded {
79// // server-side context might have timed-out first (due to clock skew)
80// // while original client-side context is not timed-out yet
81// }
82// } else {
83// // bad cluster endpoints, which are not etcd servers
84// }
85// }
86//
87// go func() { cli.Close() }()
88// _, err := kvc.Get(ctx, "a")
89// if err != nil {
90// // with etcd clientv3 <= v3.3
91// if err == context.Canceled {
92// // grpc balancer calls 'Get' with an inflight client.Close
93// } else if err == grpc.ErrClientConnClosing { // <= gRCP v1.7.x
94// // grpc balancer calls 'Get' after client.Close.
95// }
96// // with etcd clientv3 >= v3.4
97// if clientv3.IsConnCanceled(err) {
98// // gRPC client connection is closed
99// }
100// }
101//
102// The grpc load balancer is registered statically and is shared across etcd clients.
103// To enable detailed load balancer logging, set the ETCD_CLIENT_DEBUG environment
104// variable. E.g. "ETCD_CLIENT_DEBUG=1".
105//
106package clientv3