1caaa9ed4a
Update to Go 1.12.5 testing. Remove deprecated unused and gosimple pacakges, and mask staticcheck 1006. Also, fix unconvert errors related to unnecessary type conversions and following staticcheck errors: - remove redundant return statements - use for range instead of for select - use time.Since instead of time.Now().Sub - omit comparison to bool constant - replace T.Fatal and T.Fatalf in tests with T.Error and T.Fatalf respectively because the goroutine calls T.Fatal must be called in the same goroutine as the test - fix error strings that should not be capitalized - use sort.Strings(...) instead of sort.Sort(sort.StringSlice(...)) - use he status code of Canceled instead of grpc.ErrClientConnClosing which is deprecated - use use status.Errorf instead of grpc.Errorf which is deprecated Related #10528 #10438
etcd/clientv3
etcd/clientv3 is the official Go etcd client for v3.
Install
go get go.etcd.io/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 := cli.Put(ctx, "sample_key", "sample_value")
cancel()
if err != nil {
// handle error!
}
// use the response
For full compatibility, it is recommended to vendor builds using etcd's vendored packages, using tools like golang/dep, as in vendor directories.
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.