一、目标
二、使用步骤
1. 安装 consul
我们可以直接使用官方提供的二进制文件来进行安装部署，其官网地址为 https://www.consul.io/downloads
下载后为可执行文件，在我们开发试验过程中，可以直接使用 consul agent -dev 命令来启动一个单节点的 consul
在启动的打印日志中可以看到 agent: Started HTTP server on 127.0.0.1:8500 (tcp), 我们可以在浏览器直接访问 127.0.0.1:8500 即可看到如下
这里我们的 consul 就启动成功了
2. 服务注册
在网络编程中，一般会提供项目的 IP、PORT、PROTOCOL，在服务治理中，我们还需要知道对应的服务名、实例名以及一些自定义的扩展信息
在这里使用 ServiceInstance 接口来规定注册服务时必须的一些信息，同时用 DefaultServiceInstance 实现
type ServiceInstance interface { // return The unique instance ID as registered. GetInstanceId() string // return The service ID as registered. GetServiceId() string // return The hostname of the registered service instance. GetHost() string // return The port of the registered service instance. GetPort() int // return Whether the port of the registered service instance uses HTTPS. IsSecure() bool // return The key / value pair metadata associated with the service instance. GetMetadata() map[string]string }type DefaultServiceInstance struct { InstanceId string ServiceId string Host string Port int Secure bool Metadata map[string]string }func NewDefaultServiceInstance(serviceId string, host string, port int, secure bool, metadata map[string]string, instanceId string) (*DefaultServiceInstance, error) { // 如果没有传入 IP 则获取一下，这个方法在多网卡的情况下，并不好用 if len(host) == 0 { localIP, err := util.GetLocalIP() if err != nil { return nil, err } host = localIP } if len(instanceId) == 0 { instanceId = serviceId + "-" + strconv.FormatInt(time.Now().Unix(), 10) + "-" + strconv.Itoa(rand.Intn(9000)+1000) } return &DefaultServiceInstance{InstanceId: instanceId, ServiceId: serviceId, Host: host, Port: port, Secure: secure, Metadata: metadata}, nil }func (serviceInstance DefaultServiceInstance) GetInstanceId() string { return serviceInstance.InstanceId }func (serviceInstance DefaultServiceInstance) GetServiceId() string { return serviceInstance.ServiceId }func (serviceInstance DefaultServiceInstance) GetHost() string { return serviceInstance.Host }func (serviceInstance DefaultServiceInstance) GetPort() int { return serviceInstance.Port }func (serviceInstance DefaultServiceInstance) IsSecure() bool { return serviceInstance.Secure }func (serviceInstance DefaultServiceInstance) GetMetadata() map[string]string { return serviceInstance.Metadata }定义接口
在上面规定了需要注册的服务的必要信息，下面定义下服务注册和剔除的方法
type ServiceRegistry interface { Register(serviceInstance cloud.ServiceInstance) bool Deregister() }具体实现
因为 consul 提供了 http 接口来对 consul 进行操作，我们也可以使用 http 请求方式进行注册和剔除操作，具体 http 接口文档见 https://www.consul.io/api-docs, consul 默认提供了go 语言的实现，这里直接使用 github.com/hashicorp/consul/api
import ( "errors" "fmt" "github.com/hashicorp/consul/api" "strconv" "unsafe" )type consulServiceRegistry struct { serviceInstances map[string]map[string]cloud.ServiceInstance client api.Client localServiceInstance cloud.ServiceInstance}func (c consulServiceRegistry) Register(serviceInstance cloud.ServiceInstance) bool { // 创建注册到consul的服务到 registration := new(api.AgentServiceRegistration) registration.ID = serviceInstance.GetInstanceId() registration.Name = serviceInstance.GetServiceId() registration.Port = serviceInstance.GetPort() var tags []string if serviceInstance.IsSecure() { tags = append(tags, "secure=true") } else { tags = append(tags, "secure=false") } if serviceInstance.GetMetadata() != nil { var tags []string for key, value := range serviceInstance.GetMetadata() { tags = append(tags, key+"="+value) } registration.Tags = tags } registration.Tags = tags registration.Address = serviceInstance.GetHost() // 增加consul健康检查回调函数 check := new(api.AgentServiceCheck) schema := "http" if serviceInstance.IsSecure() { schema = "https" } check.HTTP = fmt.Sprintf("%s://%s:%d/actuator/health", schema, registration.Address, registration.Port) check.Timeout = "5s" check.Interval = "5s" check.DeregisterCriticalServiceAfter = "20s" // 故障检查失败30s后 consul自动将注册服务删除 registration.Check = check // 注册服务到consul err := c.client.Agent().ServiceRegister(registration) if err != nil { fmt.Println(err) return false } if c.serviceInstances == nil { c.serviceInstances = map[string]map[string]cloud.ServiceInstance{} } services := c.serviceInstances[serviceInstance.GetServiceId()] if services == nil { services = map[string]cloud.ServiceInstance{} } services[serviceInstance.GetInstanceId()] = serviceInstance c.serviceInstances[serviceInstance.GetServiceId()] = services c.localServiceInstance = serviceInstance return true }// deregister a servicefunc (c consulServiceRegistry) Deregister() { if c.serviceInstances == nil { return } services := c.serviceInstances[c.localServiceInstance.GetServiceId()] if services == nil { return } delete(services, c.localServiceInstance.GetInstanceId()) if len(services) == 0 { delete(c.serviceInstances, c.localServiceInstance.GetServiceId()) } _ = c.client.Agent().ServiceDeregister(c.localServiceInstance.GetInstanceId()) c.localServiceInstance = nil }// new a consulServiceRegistry instance// token is optionalfunc NewConsulServiceRegistry(host string, port int, token string) (*consulServiceRegistry, error) { if len(host) < 3 { return nil, errors.New("check host") } if port <= 0 || port > 65535 { return nil, errors.New("check port, port should between 1 and 65535") } config := api.DefaultConfig() config.Address = host + ":" + strconv.Itoa(port) config.Token = token client, err := api.NewClient(config) if err != nil { return nil, err } return &consulServiceRegistry{client: *client}, nil }测试用例
注册服务的代码基本完成，来测试一下
func TestConsulServiceRegistry(t *testing.T) { host := "127.0.0.1" port := 8500 registryDiscoveryClient, _ := extension.NewConsulServiceRegistry(host, port, "") ip, err := util.GetLocalIP() if err != nil { t.Error(err) } serviceInstanceInfo, _ := cloud.NewDefaultServiceInstance("go-user-server", "", 8090, false, map[string]string{"user":"zyn"}, "") registryDiscoveryClient.Register(serviceInstanceInfo) r := gin.Default() // 健康检测接口，其实只要是 200 就认为成功了 r.GET("/actuator/health", func(c *gin.Context) { c.JSON(200, gin.H{ "message": "pong", }) }) err = r.Run(":8090") if err != nil{ registryDiscoveryClient.Deregister() } }如果成功，则会在 consul 看到 go-user-server 这个服务
3. 服务发现
在服务发现中，一般会需要两个方法
获取所有的服务列表
获取指定的服务的所有实例信息
接口定义
type DiscoveryClient interface { /** * Gets all ServiceInstances associated with a particular serviceId. * @param serviceId The serviceId to query. * @return A List of ServiceInstance. */ GetInstances(serviceId string) ([]cloud.ServiceInstance, error) /** * @return All known service IDs. */ GetServices() ([]string, error)}具体实现
来实现一下
type consulServiceRegistry struct { serviceInstances map[string]map[string]cloud.ServiceInstance client api.Client localServiceInstance cloud.ServiceInstance}func (c consulServiceRegistry) GetInstances(serviceId string) ([]cloud.ServiceInstance, error) { catalogService, _, _ := c.client.Catalog().Service(serviceId, "", nil) if len(catalogService) > 0 { result := make([]cloud.ServiceInstance, len(catalogService)) for index, sever := range catalogService { s := cloud.DefaultServiceInstance{ InstanceId: sever.ServiceID, ServiceId: sever.ServiceName, Host: sever.Address, Port: sever.ServicePort, Metadata: sever.ServiceMeta, } result[index] = s } return result, nil } return nil, nil }func (c consulServiceRegistry) GetServices() ([]string, error) { services, _, _ := c.client.Catalog().Services(nil) result := make([]string, unsafe.Sizeof(services)) index := 0 for serviceName, _ := range services { result[index] = serviceName index++ } return result, nil }// new a consulServiceRegistry instance // token is optional func NewConsulServiceRegistry(host string, port int, token string) (*consulServiceRegistry, error) { if len(host) < 3 { return nil, errors.New("check host") } if port <= 0 || port > 65535 { return nil, errors.New("check port, port should between 1 and 65535") } config := api.DefaultConfig() config.Address = host + ":" + strconv.Itoa(port) config.Token = token client, err := api.NewClient(config) if err != nil { return nil, err } return &consulServiceRegistry{client: *client}, nil }测试用例
func TestConsulServiceDiscovery(t *testing.T) { host := "127.0.0.1" port := 8500 token := "" registryDiscoveryClient, err := extension.NewConsulServiceRegistry(host, port, token) if err != nil { panic(err) } t.Log(registryDiscoveryClient.GetServices()) t.Log(registryDiscoveryClient.GetInstances("go-user-server")) }结果
consul_service_registry_test.go:57: [consul go-user-server ] <nil> consul_service_registry_test.go:59: [{go-user-server-1602590661-56179 go-user-server 127.0.0.1 8090 false map[user:zyn]}] <nil>总结
通过使用 consul api 我们可以简单的实现基于 consul 的服务发现，在通过结合 http rpc 就可简单的实现服务的调用，下面一章来简单讲下 go 如何发起 http 请求，为我们做 rpc 做个铺垫
