etcd/clientv3

etcd/clientv3

etcd/clientv3 is the official Go etcd client for v3.

Install

go get github.com/coreos/etcd/clientv3

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 := kvc.Put(ctx, "sample_key", "sample_value")
cancel()
if err != nil {
    // handle error!
}
// use the response

etcd uses cmd/vendor directory to store external dependencies, which are to be compiled into etcd release binaries. client can be imported without vendoring. For full compatibility, it is recommended to vendor builds using etcd's vendored packages, using tools like godep, as in vendor directories. For more detail, please read Go vendor design.

Error Handling

etcd client returns 2 types of errors:

1. context error: canceled or deadline exceeded.
2. gRPC error: see v3rpc/error.

Here is the example code to handle client errors:

resp, err := kvc.Put(ctx, "", "")
if err != nil {
	if err == context.Canceled {
		// ctx is canceled by another routine
	} else if err == context.DeadlineExceeded {
		// ctx is attached with a deadline and it exceeded
	} else if verr, ok := err.(*v3rpc.ErrEmptyKey); ok {
		// process (verr.Errors)
	} else {
		// bad cluster endpoints, which are not etcd servers
	}
}

Examples

More code examples can be found at GoDoc.