5d7c1db3a9
This is not yet implementation, just API and tests to be filled with implementation in next CLs, tracked by: https://github.com/etcd-io/etcd/issues/12652 We propose here 3 packages: - clientv3/naming/endpoints -> That is abstraction layer over etcd that allows to write, read & watch Endpoints information. It's independent from GRPC API. It hides the storage details. - clientv3/naming/endpoints/internal -> That contains the grpc's compatible Update class to preserve the internal JSON mashalling format. - clientv3/naming/resolver -> That implements the GRPC resolver API, such that etcd can be used for connection.Dial in grpc. Please see the grpc_naming.md document changes & grpcproxy/cluster.go new integration, to see how the new abstractions work.
etcd/clientv3
etcd/clientv3 is the official Go etcd client for v3.
Install
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
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.