config-etcd (This is a community driven project)

中文

etcd as config center for service governance.

Usage

Basic

Server

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

package main

import (
	"context"
	"log"
	"time"

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

type configLog struct{}

func (cl *configLog) Apply(opt *utils.Options) {
	fn := func(k *etcd.Key) {
		klog.Infof("etcd config %v", k)
	}
	opt.EtcdCustomFunctions = append(opt.EtcdCustomFunctions, fn)
}

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

	cl := &configLog{}

	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, cl)),
	)
	if err != nil {
		log.Fatal(err)
	}
	for {
		req := &api.Request{Message: "my request"}
		resp, err := client.Echo(context.Background(), req)
		if err != nil {
			klog.Errorf("take request error: %v", err)
		} else {
			klog.Infof("receive response %v", resp)
		}
		time.Sleep(time.Second * 10)
	}
}

Etcd Configuration

CustomFunction

Provide the mechanism to custom the etcd parameter Key.

type Key struct {
    Prefix string
    Path   string
}

Options Variable

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
ServerPathFormat	{{.ServerServiceName}}/{{.Category}}	Use go template syntax rendering to generate the appropriate ID, and use ServiceName Category two metadatas that can be customised
Timeout	5 * time.Second	five seconds timeout
LoggerConfig	NULL	Default Logger
ConfigParser	defaultConfigParser	The default is the parser that parses json

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 
  }
}

Degradation: Category=degradation

JSON Schema

Variable	Introduction
enable	Whether to enable degradation
percentage	The percentage of dropped requests

Example：

configPath: /KitexConfig/ClientName/ServiceName/degradation

{
  "enable": true,
  "percentage": 30
}

Note: Degradation is not enabled by default.

More Info

Refer to example for more usage.

Compatibility

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

maintained by: ViolaPioggia