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