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107 lines
3.6 KiB
107 lines
3.6 KiB
// Copyright 2016 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package clientv3 implements the official Go etcd client for v3.
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//
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// Create client using `clientv3.New`:
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//
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// // expect dial time-out on ipv4 blackhole
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// _, err := clientv3.New(clientv3.Config{
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// Endpoints: []string{"http://254.0.0.1:12345"},
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// DialTimeout: 2 * time.Second,
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// })
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//
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// // etcd clientv3 >= v3.2.10, grpc/grpc-go >= v1.7.3
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// if err == context.DeadlineExceeded {
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// // handle errors
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// }
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//
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// // etcd clientv3 <= v3.2.9, grpc/grpc-go <= v1.2.1
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// if err == grpc.ErrClientConnTimeout {
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// // handle errors
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// }
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//
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// cli, err := clientv3.New(clientv3.Config{
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// Endpoints: []string{"localhost:2379", "localhost:22379", "localhost:32379"},
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// DialTimeout: 5 * time.Second,
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// })
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// if err != nil {
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// // handle error!
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// }
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// defer cli.Close()
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//
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// Make sure to close the client after using it. If the client is not closed, the
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// connection will have leaky goroutines.
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//
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// To specify a client request timeout, wrap the context with context.WithTimeout:
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//
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// ctx, cancel := context.WithTimeout(context.Background(), timeout)
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// resp, err := kvc.Put(ctx, "sample_key", "sample_value")
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// cancel()
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// if err != nil {
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// // handle error!
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// }
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// // use the response
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//
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// The Client has internal state (watchers and leases), so Clients should be reused instead of created as needed.
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// Clients are safe for concurrent use by multiple goroutines.
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//
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// etcd client returns 3 types of errors:
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//
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// 1. context error: canceled or deadline exceeded.
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// 2. gRPC status error: e.g. when clock drifts in server-side before client's context deadline exceeded.
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// 3. gRPC error: see https://github.com/etcd-io/etcd/blob/master/etcdserver/api/v3rpc/rpctypes/error.go
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//
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// Here is the example code to handle client errors:
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//
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// resp, err := kvc.Put(ctx, "", "")
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// if err != nil {
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// if err == context.Canceled {
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// // ctx is canceled by another routine
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// } else if err == context.DeadlineExceeded {
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// // ctx is attached with a deadline and it exceeded
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// } else if err == rpctypes.ErrEmptyKey {
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// // client-side error: key is not provided
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// } else if ev, ok := status.FromError(err); ok {
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// code := ev.Code()
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// if code == codes.DeadlineExceeded {
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// // server-side context might have timed-out first (due to clock skew)
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// // while original client-side context is not timed-out yet
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// }
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// } else {
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// // bad cluster endpoints, which are not etcd servers
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// }
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// }
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//
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// go func() { cli.Close() }()
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// _, err := kvc.Get(ctx, "a")
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// if err != nil {
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// // with etcd clientv3 <= v3.3
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// if err == context.Canceled {
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// // grpc balancer calls 'Get' with an inflight client.Close
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// } else if err == grpc.ErrClientConnClosing { // <= gRCP v1.7.x
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// // grpc balancer calls 'Get' after client.Close.
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// }
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// // with etcd clientv3 >= v3.4
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// if clientv3.IsConnCanceled(err) {
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// // gRPC client connection is closed
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// }
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// }
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//
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// The grpc load balancer is registered statically and is shared across etcd clients.
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// To enable detailed load balancer logging, set the ETCD_CLIENT_DEBUG environment
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// variable. E.g. "ETCD_CLIENT_DEBUG=1".
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//
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package clientv3
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