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关于golang:Go-Go-使用-consul-做服务发现

jiezi

系列文章目录

@TOC

前言

后面一章讲了微服务的一些长处和毛病，那如何做到

一、指标

二、应用步骤

1. 装置 consul

咱们能够间接应用官网提供的二进制文件来进行装置部署，其官网地址为 https://www.consul.io/downloads

下载后为可执行文件，在咱们开发试验过程中，能够间接应用 consul agent -dev 命令来启动一个单节点的 consul

在启动的打印日志中能够看到 agent: Started HTTP server on 127.0.0.1:8500 (tcp), 咱们能够在浏览器间接拜访 127.0.0.1:8500 即可看到如下

这里咱们的 consul 就启动胜利了

2. 服务注册

在网络编程中，个别会提供我的项目的 IP、PORT、PROTOCOL，在服务治理中，咱们还须要晓得对应的服务名、实例名以及一些自定义的扩大信息

在这里应用 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，这个办法在多网卡的状况下，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

在下面规定了须要注册的服务的必要信息，上面定义下服务注册和剔除的办法

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，咱们也能够应用 http 申请形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，这里间接应用 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 {
    // 创立注册到 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()

    // 减少 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" // 故障查看失败 30s 后 consul 主动将注册服务删除
    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 service
func (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 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

注册服务的代码根本实现，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()
    // 衰弱检测接口，其实只有是 200 就认为胜利了
    r.GET("/actuator/health", func(c *gin.Context) {
        c.JSON(200, gin.H{"message": "pong",})
    })
    err = r.Run(":8090")
    if err != nil{registryDiscoveryClient.Deregister()
    }
}

如果胜利，则会在 consul 看到 go-user-server 这个服务

3. 服务发现

在服务发现中，个别会须要两个办法

  1. 获取所有的服务列表
  2. 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"))
}

后果

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

通过应用 consul api 咱们能够简略的实现基于 consul 的服务发现，在通过联合 http rpc 就可简略的实现服务的调用，上面一章来简略讲下 go 如何发动 http 申请，为咱们做 rpc 做个铺垫

具体代码见 https://github.com/zhangyunan…

参考

  • https://www.consul.io/api-docs
  • https://github.com/hashicorp/…
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