61ebb98e55
Gets should retry on transient failure, but the txn inserts a write, skipping the retry logic in the client. Instead, check the error if the txn should be retried. Fixes #8372
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 := cli.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:
- 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.
Examples
More code examples can be found at GoDoc.