eeafcef0d2
instead of v3.0.0-000101010000000-00000000000, that might be misleading as we don't develop etcd v3.0.0 any longer. This version is a virtual version and is not supposed to be tagged within the repository. We should tag real versions like: 3.5.0-alpha.0. Please notice that go.etcd.io/etcd/client/v2 will be versioned as `v2.305.0-pre`. The reason is that client v2 must have v2 version. I propose a convention to envode the major version as 100x in minor version to make the association to the underlying repository clear, staying within v2 version family. The change was generated using: ``` DRY_RUN=false TARGET_VERSION="v3.5.0-pre" ./scripts/release_mod.sh update_versions ```
etcd/clientv3
etcd/clientv3 is the official Go etcd client for v3.
Install
go get go.etcd.io/etcd/client/v3
Get started
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.
Error Handling
etcd client returns 2 types of errors:
- context error: canceled or deadline exceeded.
- gRPC error: see api/v3rpc/rpctypes.
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)
}
}
Metrics
The etcd client optionally exposes RPC metrics through go-grpc-prometheus. See the examples.
Namespacing
The namespace package provides clientv3 interface wrappers to transparently isolate client requests to a user-defined prefix.
Request size limit
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.
Examples
More code examples can be found at GoDoc.