服务注册与发现

接口实现

Registry 接口分为两个，Registrar 为实例注册和反注册，Discovery 为服务实例列表获取

type Registrar interface {
    // 注册实例
    Register(ctx context.Context, service *ServiceInstance) error
    // 反注册实例
    Deregister(ctx context.Context, service *ServiceInstance) error
}

type Discovery interface {
    // 根据 serviceName 直接拉取实例列表
    GetService(ctx context.Context, serviceName string) ([]*ServiceInstance, error)
    // 根据 serviceName 阻塞式订阅一个服务的实例列表信息
    Watch(ctx context.Context, serviceName string) (Watcher, error)
}

已支持的实现：

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

使用方式

注册服务实例

创建一个 Registrar（以 consul 为例），将 Registrar 注入进 Kratos 应用实例中，Kratos 会自动完成实例注册和反注册

import (
    consul "github.com/go-kratos/kratos/contrib/registry/consul/v2"
    "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),
)

如果使用 etcd 或是其它实现，只需要根据不同的实现来创建 Registry 后传入

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),
)

服务发现（gRPC）

创建一个 Discoverer（以 consul 为例），根据 Dial url 格式 <schema>://[authority]/<service-name> 创建一个 Endpoint，通过 grpc.WithDiscoverer，grpc.WithEndpoint 创建一个 grpc connection

import (
    "context"
    consul "github.com/go-kratos/kratos/contrib/registry/consul/v2"
    "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)
}

与服务注册相同，如果使用 etcd 或是其它实现，只需要根据不同的实现来创建 Discovery 后传入

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 dis with etcd client
dis := etcd.New(client)
endpoint := "discovery:///provider"
conn, err := grpc.Dial(context.Background(), grpc.WithEndpoint(endpoint), grpc.WithDiscovery(dis))
if err != nil {
    panic(err)
}