Registry

Interface

Registry has two interface, the Registrar is for services’ register and deregister, the Discovery is for fetching the list of services.

type Registrar interface {
    // register the service
    Register(ctx context.Context, service *ServiceInstance) error
    // deregister the service
    Deregister(ctx context.Context, service *ServiceInstance) error
}

type Discovery interface {
    // fetch the service list of serviceName
    Fetch(ctx context.Context, serviceName string) ([]*ServiceInstance, error)
    // subscribe to a list of serviceName
    Watch(ctx context.Context, serviceName string) (Watcher, error)
}

Implementations:

• consul
• discovery
• etcd
• kubernetes
• nacos
• polaris
• zookeeper

Usage

Register a Service

Create a Registrar(e.g. consul) and inject it to Kratos applications. Then the framework will do register and deregister automatically.

import (
    consul "github.com/go-kratos/consul/registry"
    "github.com/hashicorp/consul/api"
)
// new consul client
client, err := api.NewClient(api.DefaultConfig())
if err != nil {
    panic(err)
}
// new reg with consul client
reg := consul.New(client)
app := kratos.New(
    // service-name
    kratos.Name(Name),
    kratos.Version(Version),
    kratos.Metadata(map[string]string{}),
    kratos.Logger(logger),
    kratos.Server(
        hs,
        gs,
    ),
    // with registrar
    kratos.Registrar(reg),
)

If use etcd or any other implementations, you can create a Registrar with other client.

import (
    "github.com/go-kratos/kratos/contrib/registry/etcd/v2"
    clientv3 "go.etcd.io/etcd/client/v3"
)
// new etcd client
client, err := clientv3.New(clientv3.Config{
    Endpoints: []string{"127.0.0.1:2379"},
})
if err != nil {
    panic(err)
}
// new reg with etcd client
reg := etcd.New(client)
app := kratos.New(
    // service-name
    kratos.Name(Name),
    kratos.Version(Version),
    kratos.Metadata(map[string]string{}),
    kratos.Logger(logger),
    kratos.Server(
        hs,
        gs,
    ),
    // with registrar
    kratos.Registrar(reg),
)

Service Discovery (gRPC)

Create a Registrar(e.g. consul), create an Endpoint with url format as <schema>://[authority]/<service-name>, then use grc.WithDiscovery and grpc.WithEndpoint as the options of the Dial method to get the gRPC connection.

import (
    "context"
    consul "github.com/go-kratos/consul/registry"
    "github.com/go-kratos/kratos/v2/transport/grpc"
    "github.com/hashicorp/consul/api"
)
// new consul client
client, err := api.NewClient(api.DefaultConfig())
if err != nil {
    panic(err)
}
// new dis with consul client
dis := consul.New(client)
endpoint := "discovery:///provider"
conn, err := grpc.Dial(context.Background(), grpc.WithEndpoint(endpoint), grpc.WithDiscovery(dis))
if err != nil {
    panic(err)
}

It is the same as Register, if use etcd or any other implementations, you can create a Discovery with other client.

import (
    "github.com/go-kratos/kratos/contrib/registry/etcd/v2"
    "github.com/go-kratos/kratos/v2/transport/grpc"
    clientv3 "go.etcd.io/etcd/client/v3"
)
// new etcd client
client, err := clientv3.New(clientv3.Config{
    Endpoints: []string{"127.0.0.1:2379"},
})
if err != nil {
    panic(err)
}
// new dis with etcd client
dis := etcd.New(client)
// This Dial need to use DialInsecure() or use grpc.WithTransportCredentials in Dial option
endpoint := "discovery:///provider"
conn, err := grpc.Dial(context.Background(), grpc.WithEndpoint(endpoint), grpc.WithDiscovery(dis))
if err != nil {
    panic(err)
}