Client Option


Add some options when creating a client:

client, err := echo.NewClient("targetService", client.WithXXXX...)

Basic Options


func WithClientBasicInfo(ebi *rpcinfo.EndpointBasicInfo) Option

Set the basic infos for client, such as ServiceName, Method and Tags.


func WithHostPorts(hostports ...string) Option

Manually specifie one or more targets overrides the results discovered by the service and directly connects to the access.


func WithTransportProtocol(tp transport.Protocol) Option

Set the transport protocol, configure the transport protocol on the message protocol. Thrift/KitexProtobuf can configure TTHeader, TTHeaderFramed, and Framed. In addition, Framed is not strictly a transmission protocol. In order to distinguish it for PurePayload, it is also configured as a transmission protocol. PurePayload means that there is no transmission protocol; if it is configured as GRPC, it means that the GRPC protocol is used. , the transmission protocol of GRPC is HTTP2, but for the convenience of users' understanding, it is directly used as the configuration of the transmission protocol. Note that configuring GRPC needs to use Protobuf to define Service. If GRPC is not configured, KitexProtobuf protocol is used by default.


func WithShortConnection() Option

Enable short connections. More


func WithLongConnection(cfg connpool.IdleConfig) Option

Enable long connections. More


func WithMuxConnection(connNum int) Option

Enable mux connections. Server side also need to turn on this option, or it won’t work. More


func WithMiddleware(mw endpoint.Middleware) Option

Add a middleware that executes after service level circuit breaker and timeout middleware. More


func WithInstanceMW(mw endpoint.Middleware) Option

Add a middleware that executes after service discovery and load balance. If instance level circuit breaker exists, then it will execute after that. (If proxy is used, it will not be called, such as mesh mode). More


func WithMiddlewareBuilder(mwb endpoint.MiddlewareBuilder) Option

Add middleware depends on the context passed in by the framework that contains runtime configuration information (the context of non-RPC calls), so that the middleware can take advantage of the framework’s information when initializing.


func WithCircuitBreaker(s *circuitbreak.CBSuite) Option

Set the circuit breaker, which includes service circuit break and instance circuit break by default, using the example:

var opts []client.Option

cbs := circuitbreak.NewCBSuite(circuitbreak.RPCInfo2Key)
opts = append(opts, client.WithCloseCallbacks(func() error {
   // Circuit Breaker Close method is injected into CloseCallbacks to release circuit breaker related resources when the client is destroyed
opts = append(opts, client.WithCircuitBreaker(cbs))

// Dynamically updates the circuit breaker configuration
cbs.UpdateServiceCBConfig(key, config)
cbs.UpdateInstanceCBConfig(key, config)

For more details, please visit Circuit Breaker.


func WithFailureRetry(p *retry.FailurePolicy) Option

Set timeout retry rules, you can configure the maximum number of retries, the maximum time spent accumulated, the threshold of the retry circuit fault rate, the DDL abort and backoff policy. More


func WithBackupRequest(p *retry.BackupPolicy) Option

Set the policy for Backup Request, which can configure the number of requests, circuit breaker abort, and link abort. More


func WithRPCTimeout(d time.Duration) Option

Set RPC timeout. More


func WithConnectTimeout(d time.Duration) Option

Set connect timeout. More


func WithTimeoutProvider(p rpcinfo.TimeoutProvider) Option

Add a TimeoutProvider to set the RPC timeout, connection timeout, etc. policies as a whole. If You use Both WithRPCTimeout or WithConnectTimeout, the settings here will be overridden.


func WithDestService(svr string) Option

Specify the service name of the target side of the call.


func WithTag(key, val string) Option 

Add some meta information to the client, such as idc, cluster, etc., for scenarios such as auxiliary service discovery.


func WithStatsLevel(level stats.Level) Optiong

Set the stats level for client. More

gRPC Options

These options only works for scenarios where the transport protocol uses gRPC, with some parameter adjustments to gRPC transfers.


func WithGRPCConnPoolSize(s uint32) Option

WithGRPCConnPoolSize sets the value for the client connection pool size. In general, you should not adjust the size of the connection pool, otherwise it may cause performance degradation. You should adjust the size according to the actual situation.


func WithGRPCWriteBufferSize(s uint32) Option

WithGRPCWriteBufferSize determines how much data can be batched before doing a write on the wire. The corresponding memory allocation for this buffer will be twice the size to keep syscalls low. The default value for this buffer is 32KB. Zero will disable the write buffer such that each write will be on underlying connection. Note: A Send call may not directly translate to a write. It corresponds to the WriteBufferSize ServerOption of gRPC.


func WithGRPCReadBufferSize(s uint32) Option

WithGRPCReadBufferSize lets you set the size of read buffer, this determines how much data can be read at most for one read syscall. The default value for this buffer is 32KB. Zero will disable read buffer for a connection so data framer can access the underlying conn directly. It corresponds to the ReadBufferSize ServerOption of gRPC.


func WithGRPCInitialWindowSize(s uint32) Option

WithGRPCInitialWindowSize returns a Option that sets window size for stream. The lower bound for window size is 64K and any value smaller than that will be ignored. It corresponds to the InitialWindowSize ServerOption of gRPC.


func WithGRPCInitialConnWindowSize(s uint32) Option

WithGRPCInitialConnWindowSize returns an Option that sets window size for a connection. The lower bound for window size is 64K and any value smaller than that will be ignored. It corresponds to the InitialConnWindowSize ServerOption of gRPC.


func WithGRPCMaxHeaderListSize(s uint32) Option

WithGRPCMaxHeaderListSize returns a ServerOption that sets the max (uncompressed) size of header list that the server is prepared to accept. It corresponds to the MaxHeaderListSize ServerOption of gRPC.


func WithGRPCKeepaliveParams(kp grpc.ClientKeepalive) Option

WithGRPCKeepaliveParams returns a DialOption that specifies keepalive parameters for the client transport. It corresponds to the WithKeepaliveParams DialOption of gRPC.

Advanced Options


func WithSuite(suite Suite) Option

Set up a specific configuration, customize according to the scene, configure multiple options and middlewares combinations and encapsulations in the Suite. More


func WithProxy(p proxy.ForwardProxy) Option

For proxy scenarios (such as Mesh Egress), do some configuration processing, return proxy address, configure proxy. After ForwardProxy, the framework does not perform service discovery, circuit breakers, and InstanceMWs.


func WithRetryContainer(rc *retry.Container) Option

Manually set up RetryContainer. Used to retry the strategy in combination with circuit breakers. At present, three rapid implementation schemes are available: NewRetryContainer, NewRetryContainerWithCB and NewRetryContainerWithCBStat.

  • NewRetryContainerWithCB (recommended)

If you have already configured the circuit breaker, it is recommended to reuse the circuit breaker with RetryContainer to avoid additional statistics, you can use the NewRetryContainerWithCB, such as the example in the example below, enable the circuit breaker scenario, and at the same time pass the circuit breaker to RetryContainer:

   cbs := circuitbreak.NewCBSuite(circuitbreak.RPCInfo2Key)
   retryC := retry.NewRetryContainerWithCB(cbs.ServiceControl(), cbs.ServicePanel())
       var opts []client.Option
   opts = append(opts, client.WithRetryContainer(retryC))
    // enable service circuit breaker
   opts = append(opts, client.WithMiddleware(cbs.ServiceCBMW()))
  • NewRetryContainer
    • Specifies the default RetryContainer for the retry policy, which has a built-in circuit breaker.
  • NewRetryContainerWithCBStat

To customize the built-in circuit breaker ServiceCBKeyFunc settings, you can use the NewRetryContainerWithCBStat method:

   cbs := circuitbreak.NewCBSuite(YourGenServiceCBKeyFunc)
   retry.NewRetryContainerWithCBStat(cbs.ServiceControl(), cbs.ServicePanel())


func WithWarmingUp(wuo *warmup.ClientOption) Option 

Set warming up option. Kitex supports client warm-up, which allows you to pre-initialize the relevant components of service discovery and connection pooling when creating the client, avoiding large delays on the first request.

Warm up service discovery:

cli, err := myservice.NewClient(psm, client.WithWarmingUp(&warmup.ClientOption{
    ResolverOption: &warmup.ResolverOption{
        Dests: []*rpcinfo.EndpointBasicInfo{
                ServiceName: psm,
                Method: method,
                Tags: map[string]string{
                    "cluster": "default",

Warm up connection pool:

cli, err := myservice.NewClient(psm, client.WithWarmingUp(&warmup.ClientOption{
    PoolOption: &warmup.PoolOption{
        ConnNum: 2,


func WithCloseCallbacks(callback func() error) Option

Set close callback function.


func WithErrorHandler(f func(error) error) Option

Set the error handler function, which is executed after the server handler is executed and before the middleware executes.


func WithGeneric(g generic.Generic) Option

Specifie the generalization call type, which needs to be used in conjunction with the generalization Client/Server. More


func WithACLRules(rules ...acl.RejectFunc) Option

Set ACL permission access control, which is executed before service discovery. More


func WithConnReporterEnabled() Option

Enable connection pool reporter. More


func WithHTTPConnection() Option 

Specifie client use RPC over http.

Extended Options


func WithTracer(c stats.Tracer) Option

Add an additional Tracer. More


func WithResolver(r discovery.Resolver) Option

Specifie a resolver to do service discovery. More


func WithHTTPResolver(r http.Resolver) Option

Set HTTP resolver. More


func WithLoadBalancer(lb loadbalance.Loadbalancer, opts ...*lbcache.Options) Option 

Set load balancer. More


func WithBoundHandler(h remote.BoundHandler) Option

Add a new IO Bound handler. More


func WithCodec(c remote.Codec) Option

Specifie a Codec for scenarios that require custom protocol. More


func WithPayloadCodec(c remote.PayloadCodec) Option

Specifie a PayloadCodec. More


func WithMetaHandler(h remote.MetaHandler) Option

Add a meta handler for customizing transparent information in conjunction with the transport protocol, such as service name, invocation method, machine room, cluster, env, tracerInfo. More


func WithFirstMetaHandler(h remote.MetaHandler) Option

Add a meta handler at the first position.


func WithTransHandlerFactory(f remote.ClientTransHandlerFactory) Option 

Set transHandlerFactory. More


func WithDiagnosisService(ds diagnosis.Service) Option

Set diagnosis service. More


func WithDialer(d remote.Dialer) Option

Set dialer.


func WithConnPool(pool remote.ConnPool) Option

Set connection pool.