Etcd

Use etcd as Kitex’s service governance configuration center

Install

go get github.com/kitex-contrib/config-etcd

Suite

The configuration center adapter of etcd, kitex uses WithSuite to convert the configuration in etcd into the governance feature configuration of kitex.

The following is a complete usage example:

Server

type EtcdServerSuite struct {
    uid        int64
    etcdClient etcd.Client // etcd client in config-etcd
    service    string
    opts       utils.Options
}

Function Signature:

func NewSuite(service string, cli etcd.Client, opts ...utils.Option,) *EtcdServerSuite

Sample code:

package main

import (
	"context"
	"log"

	"github.com/cloudwego/kitex-examples/kitex_gen/api"
	"github.com/cloudwego/kitex-examples/kitex_gen/api/echo"
	"github.com/cloudwego/kitex/pkg/klog"
	"github.com/cloudwego/kitex/pkg/rpcinfo"
	"github.com/cloudwego/kitex/server"
	"github.com/kitex-contrib/config-etcd/etcd"
	etcdServer "github.com/kitex-contrib/config-etcd/server"
)

var _ api.Echo = &EchoImpl{}

// EchoImpl implements the last service interface defined in the IDL.
type EchoImpl struct{}

// Echo implements the Echo interface.
func (s *EchoImpl) Echo(ctx context.Context, req *api.Request) (resp *api.Response, err error) {
	klog.Info("echo called")
	return &api.Response{Message: req.Message}, nil
}

func main() {
	serviceName := "ServiceName" // your server-side service name
	etcdClient, _ := etcd.NewClient(etcd.Options{})
	svr := echo.NewServer(
		new(EchoImpl),
		server.WithServerBasicInfo(&rpcinfo.EndpointBasicInfo{ServiceName: serviceName}),
		server.WithSuite(etcdServer.NewSuite(serviceName, etcdClient)),
	)
	if err := svr.Run(); err != nil {
		log.Println("server stopped with error:", err)
	} else {
		log.Println("server stopped")
	}
}

Client

type EtcdServerSuite struct {
    uid        int64
    etcdClient etcd.Client // etcd client in config-etcd
    service    string
    opts       utils.Options
}

Function Signature:

func NewSuite(service,client string, cli etcd.Client, opts ...utils.Option,) *EtcdServerSuite

Sample code:

package main

import (
    "log"

    "github.com/cloudwego/kitex-examples/kitex_gen/api"
    "github.com/cloudwego/kitex-examples/kitex_gen/api/echo"
    "github.com/cloudwego/kitex/client"
    etcdclient "github.com/kitex-contrib/config-etcd/client"
    "github.com/kitex-contrib/config-etcd/etcd"
)

func main() {
    etcdClient, err := etcd.NewClient(etcd.Options{})
    if err != nil {
        panic(err)
    }

    serviceName := "ServiceName" // your server-side service name
    clientName := "ClientName"   // your client-side service name
    client, err := echo.NewClient(
        serviceName,
        client.WithHostPorts("0.0.0.0:8888"),
        client.WithSuite(etcdclient.NewSuite(serviceName, clientName, etcdClient)),
    )
    if err != nil {
        log.Fatal(err)
    }
}

NewClient

Create client.

Function Signature:

func NewClient(opts Options) (Client, error)

Sample code:

package main

import "github.com/kitex-contrib/config-etcd/etcd"

func main() {
    etcdClient, err := etcd.NewClient(etcd.Options{})
    if err!=nil {
        panic(err)
    }
}

SetParser

Set a custom parser for deserializing etcd configuration. If not specified, it will be the default parser.

The default parser parses configuration in json format.

Function Signature:

func (c *client) SetParser(parser ConfigParser)

type ConfigParser interface {
	Decode(data string, config interface{}) error
}

Sample code:

Set the configuration for parsing yaml types.

package main

import "github.com/kitex-contrib/config-etcd/etcd"

func (p *parser) Decode(data string, config interface{}) error {
    return yaml.Unmarshal([]byte(data), config)
}

type parser struct{}

func main() {
    etcdClient, err := etcd.NewClient(etcd.Options{})
    if err!=nil {
        panic(err)
    }
    etcdClient.SetParser(&parser{})
}

Etcd Configuration

Options Struct

type Options struct {
	Node             []string
	Prefix           string
	ServerPathFormat string
	ClientPathFormat string
	Timeout          time.Duration
	LoggerConfig     *zap.Config
	ConfigParser     ConfigParser
}

Options Variable

type Key struct {
    Prefix string
    Path   string
}

The key in etcd consists of prefix and path, where prefix is the prefix and path is the path.

Variable Name Default Value Introduction
Node 127.0.0.1:2379 Etcd server nodes
Prefix /KitexConfig The prefix of Etcd
ClientPathFormat {{.ClientServiceName}}/{{.ServerServiceName}}/{{.Category}} Use go template syntax rendering to generate the appropriate ID, and use ClientServiceName ServiceName Category three metadata that can be customised, used with Prefix to form the key in etcd
ServerPathFormat {{.ServerServiceName}}/{{.Category}} Use go template syntax rendering to generate the appropriate ID, and use ServiceName Category two metadatas that can be customised, used with Prefix to form the key in etcd
Timeout 5 * time.Second five seconds timeout
LoggerConfig NULL Default Logger
ConfigParser defaultConfigParser The default parser, which defaults to parsing json format data

Governance Policy

The configPath and configPrefix in the following example use default values, the service name is ServiceName and the client name is ClientName.

Rate Limit

Category=limit

Currently, current limiting only supports the server side, so ClientServiceName is empty.

JSON Schema

Variable Introduction
connection_limit Maximum concurrent connections
qps_limit Maximum request number every 100ms

Example:

configPath: /KitexConfig/ServiceName/limit

{
  "connection_limit": 100,
  "qps_limit": 2000
}

Note:

  • The granularity of the current limit configuration is server global, regardless of client or method.
  • Not configured or value is 0 means not enabled.
  • connection_limit and qps_limit can be configured independently, e.g. connection_limit = 100, qps_limit = 0

Retry Policy

Category=retry

JSON Schema

Variable Introduction
type 0: failure_policy 1: backup_policy
failure_policy.backoff_policy Can only be set one of fixed none random

Example:

configPath: /KitexConfig/ClientName/ServiceName/retry

{
    "*": {  
        "enable": true,
        "type": 0,                 
        "failure_policy": {
            "stop_policy": {
                "max_retry_times": 3,
                "max_duration_ms": 2000,
                "cb_policy": {
                    "error_rate": 0.3
                }
            },
            "backoff_policy": {
                "backoff_type": "fixed", 
                "cfg_items": {
                    "fix_ms": 50
                }
            },
            "retry_same_node": false
        }
    },
    "echo": { 
        "enable": true,
        "type": 1,                 
        "backup_policy": {
            "retry_delay_ms": 100,
            "retry_same_node": false,
            "stop_policy": {
                "max_retry_times": 2,
                "max_duration_ms": 300,
                "cb_policy": {
                    "error_rate": 0.2
                }
            }
        }
    }
}

Note: retry.Container has built-in support for specifying the default configuration using the * wildcard (see the getRetryer method for details).

RPC Timeout

Category=rpc_timeout

JSON Schema

Example:

configPath: /KitexConfig/ClientName/ServiceName/rpc_timeout

{
  "*": {
    "conn_timeout_ms": 100,
    "rpc_timeout_ms": 3000
  },
  "echo": {
    "conn_timeout_ms": 50,
    "rpc_timeout_ms": 1000
  }
}

Note: The circuit breaker implementation of kitex does not currently support changing the global default configuration (see initServiceCB for details).

Circuit Break

Category=circuit_break

JSON Schema

Variable Introduction
min_sample Minimum statistical sample number

Example:

The echo method uses the following configuration (0.3, 100) and other methods use the global default configuration (0.5, 200).

configPath: /KitexConfig/ClientName/ServiceName/circuit_break

{
  "echo": {
    "enable": true,
    "err_rate": 0.3, 
    "min_sample": 100 
  }
}

Compatibility

For grpc compatibility, the version of Go must >=1.19


Last modified February 29, 2024 : docs: add doc for command cwgo-doc (#955) (7213e1f)