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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:

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>://[namespace]/<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://default/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://default/provider"
conn, err := grpc.Dial(context.Background(), grpc.WithEndpoint(endpoint), grpc.WithDiscovery(dis))
if err != nil {
panic(err)
}