etcd/clientv3 is the official Go etcd client for v3.
go get go.etcd.io/etcd/client/v3
Warning: As etcd 3.5.0 was not yet released, the command above does not work. After first pre-release of 3.5.0 #12498, etcd can be referenced using:
go get go.etcd.io/etcd/client/v3@v3.5.0-pre
Create client using clientv3.New:
cli, err := clientv3.New(clientv3.Config{ Endpoints: []string{"localhost:2379", "localhost:22379", "localhost:32379"}, DialTimeout: 5 * time.Second, }) if err != nil { // handle error! } defer cli.Close()
etcd v3 uses gRPC for remote procedure calls. And clientv3 uses grpc-go to connect to etcd. Make sure to close the client after using it. If the client is not closed, the connection will have leaky goroutines. To specify client request timeout, pass context.WithTimeout to APIs:
ctx, cancel := context.WithTimeout(context.Background(), timeout) resp, err := cli.Put(ctx, "sample_key", "sample_value") cancel() if err != nil { // handle error! } // use the response
For full compatibility, it is recommended to install released versions of clients using go modules.
etcd client returns 2 types of errors:
Here is the example code to handle client errors:
resp, err := cli.Put(ctx, "", "")
if err != nil {
switch err {
case context.Canceled:
log.Fatalf("ctx is canceled by another routine: %v", err)
case context.DeadlineExceeded:
log.Fatalf("ctx is attached with a deadline is exceeded: %v", err)
case rpctypes.ErrEmptyKey:
log.Fatalf("client-side error: %v", err)
default:
log.Fatalf("bad cluster endpoints, which are not etcd servers: %v", err)
}
}
The etcd client optionally exposes RPC metrics through go-grpc-prometheus. See the examples.
The namespace package provides clientv3 interface wrappers to transparently isolate client requests to a user-defined prefix.
Client request size limit is configurable via clientv3.Config.MaxCallSendMsgSize and MaxCallRecvMsgSize in bytes. If none given, client request send limit defaults to 2 MiB including gRPC overhead bytes. And receive limit defaults to math.MaxInt32.