mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-27 16:50:23 +00:00
86 lines
2.8 KiB
Markdown
86 lines
2.8 KiB
Markdown
# etcd/clientv3
|
|
|
|
[](https://etcd.io/docs)
|
|
[](https://godoc.org/go.etcd.io/etcd/clientv3)
|
|
|
|
`etcd/clientv3` is the official Go etcd client for v3.
|
|
|
|
## Install
|
|
|
|
```bash
|
|
go get go.etcd.io/etcd/clientv3
|
|
```
|
|
|
|
## Get started
|
|
|
|
Create client using `clientv3.New`:
|
|
|
|
```go
|
|
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`](https://www.grpc.io) for remote procedure calls. And `clientv3` uses
|
|
[`grpc-go`](https://github.com/grpc/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:
|
|
|
|
```go
|
|
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](https://golang.org/cmd/go/#hdr-Vendor_Directories).
|
|
|
|
## Error Handling
|
|
|
|
etcd client returns 2 types of errors:
|
|
|
|
1. context error: canceled or deadline exceeded.
|
|
2. gRPC error: see [api/v3rpc/rpctypes](https://godoc.org/go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes).
|
|
|
|
Here is the example code to handle client errors:
|
|
|
|
```go
|
|
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](https://github.com/grpc-ecosystem/go-grpc-prometheus). See the [examples](https://github.com/etcd-io/etcd/blob/master/clientv3/example_metrics_test.go).
|
|
|
|
## Namespacing
|
|
|
|
The [namespace](https://godoc.org/go.etcd.io/etcd/clientv3/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](https://godoc.org/go.etcd.io/etcd/clientv3).
|