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93 lines
3.1 KiB
Markdown
93 lines
3.1 KiB
Markdown
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# etcd/clientv3
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[](https://etcd.io/docs)
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[](https://godoc.org/go.etcd.io/etcd/clientv3)
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`etcd/clientv3` is the official Go etcd client for v3.
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## Install
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```bash
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go get go.etcd.io/etcd/client/v3
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```
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Warning: As etcd 3.5.0 was not yet released, the command above does not work.
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After first pre-release of 3.5.0 [#12498](https://github.com/etcd-io/etcd/issues/12498),
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etcd can be referenced using:
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```
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go get go.etcd.io/etcd/client/v3@v3.5.0-pre
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```
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## Get started
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Create client using `clientv3.New`:
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```go
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cli, err := clientv3.New(clientv3.Config{
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Endpoints: []string{"localhost:2379", "localhost:22379", "localhost:32379"},
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DialTimeout: 5 * time.Second,
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})
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if err != nil {
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// handle error!
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}
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defer cli.Close()
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```
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etcd v3 uses [`gRPC`](https://www.grpc.io) for remote procedure calls. And `clientv3` uses
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[`grpc-go`](https://github.com/grpc/grpc-go) to connect to etcd. Make sure to close the client after using it.
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If the client is not closed, the connection will have leaky goroutines. To specify client request timeout,
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pass `context.WithTimeout` to APIs:
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```go
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ctx, cancel := context.WithTimeout(context.Background(), timeout)
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resp, err := cli.Put(ctx, "sample_key", "sample_value")
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cancel()
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if err != nil {
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// handle error!
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}
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// use the response
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```
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For full compatibility, it is recommended to install released versions of clients using go modules.
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## Error Handling
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etcd client returns 2 types of errors:
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1. context error: canceled or deadline exceeded.
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2. gRPC error: see [api/v3rpc/rpctypes](https://godoc.org/go.etcd.io/etcd/api/v3rpc/rpctypes).
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Here is the example code to handle client errors:
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```go
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resp, err := cli.Put(ctx, "", "")
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if err != nil {
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switch err {
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case context.Canceled:
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log.Fatalf("ctx is canceled by another routine: %v", err)
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case context.DeadlineExceeded:
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log.Fatalf("ctx is attached with a deadline is exceeded: %v", err)
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case rpctypes.ErrEmptyKey:
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log.Fatalf("client-side error: %v", err)
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default:
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log.Fatalf("bad cluster endpoints, which are not etcd servers: %v", err)
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}
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}
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```
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## Metrics
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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/main/tests/integration/clientv3/examples/example_metrics_test.go).
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## Namespacing
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The [namespace](https://godoc.org/go.etcd.io/etcd/client/v3/namespace) package provides `clientv3` interface wrappers to transparently isolate client requests to a user-defined prefix.
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## Request size limit
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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`.
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## Examples
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More code [examples](https://github.com/etcd-io/etcd/tree/main/tests/integration/clientv3/examples) can be found at [GoDoc](https://pkg.go.dev/go.etcd.io/etcd/client/v3).
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