环境

安装

• protoc

下载对应版本的安装包https://github.com/protocolbuffers/protobuf/releases

解压后随便找个地方放，把bin目录地址加到环境变量中。

>protoc --version
libprotoc 3.12.0

• micro和protoc相关的go插件

#设置mod模式和代理
go env -w GO111MODULE=on
go env -w GOPROXY=https://goproxy.cn,https://proxy.golang.org,direct

#安装
go get -u -v github.com/golang/protobuf/protoc-gen-go 
go get -u -v google.golang.org/grpc
#这里若加-u选项貌似会报错，就不加了
go get -v github.com/micro/micro/v2
go get -u -v github.com/micro/go-micro/v2
go get -v github.com/micro/micro/v2/cmd/protoc-gen-micro@master

顺利安装完毕后，在$GOPATH/bin下应该会有这仨执行文件

• consul（可选）

因为micro v2版本官方弃用consul，默认改用了mdns，生产推荐etcd。参考go-micro v2弃用了consul作为默认的服务发现

所以装不装这个都可以。

https://www.consul.io/downloads.html下载对应版本，网速限制的话可以在这里https://download.csdn.net/download/HJXINKKL/12428749下

解压后添加路径到环境变量

>consul -v
Consul v1.7.3

开始创建

• 目录结构

│  go.mod
│  go.sum
│
└─helloworld
    ├─message
    │      greeter.pb.go
    │      greeter.pb.micro.go
    │      greeter.proto
    │
    └─services
            client.go
            server.go

• 初始化项目

在$GOPATH/src下

mkdir microTest
go mod init microTest

• 定义API 

创建helloworld/message/greeter.proto

syntax = "proto3";

package microTest;
option go_package = "helloworld/message";

service Greeter {
    rpc Hello (Request) returns (Response) {
    }
}

message Request {
    string name = 1;
}

message Response {
    string greeting = 2;
}

microTest下执行protoc命令，就会在helloworld/message/自动生成greeter.pb.go、greeter.pb.micro.go

protoc --micro_out=. --go_out=. helloworld/message/greeter.proto

• 创建service

创建helloworld/services/server.go文件

package main

import (
    "context"
    "fmt"

    micro "github.com/micro/go-micro/v2"
    proto "microTest/helloworld/message"
)

type Greeter struct{}

func (g *Greeter) Hello(ctx context.Context, req *proto.Request, rsp *proto.Response) error {
    rsp.Greeting = "Hello " + req.Name
    return nil
}

func main() {
    // Create a new service. Optionally include some options here.
    service := micro.NewService(
        micro.Name("greeter"),
    )

    // Init will parse the command line flags.
    service.Init()

    // Register handler
    proto.RegisterGreeterHandler(service.Server(), new(Greeter))

    // Run the server
    if err := service.Run(); err != nil {
        fmt.Println(err)
    }
}

• 创建client

创建helloworld/services/client.go文件

package main

import (
    "context"
    "fmt"

    micro "github.com/micro/go-micro/v2"
    proto "microTest/helloworld/message"
)

func main() {
    // Create a new service
    service := micro.NewService(micro.Name("greeter.client"))
    // Initialise the client and parse command line flags
    service.Init()

    // Create new greeter client
    greeter := proto.NewGreeterService("greeter", service.Client())

    // Call the greeter
    rsp, err := greeter.Hello(context.TODO(), &proto.Request{Name: "John"})
    if err != nil {
        fmt.Println(err)
    }

    // Print response
    fmt.Println(rsp.Greeting)
}

运行服务

• 启动server

go run helloworld/services/server.go

• client请求

go run helloworld/services/client.go

此时，有可能会报错

{"id":"go.micro.client","code":408,"detail":"context deadline exceeded","status":"Request Timeout"}
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x28 pc=0xeef454]

• 定位报错原因

查看服务列表，greeter服务已经启动了

> micro list services
greeter

查看指定服务信息

micro get service greeter

service  greeter

version latest

ID      Address Metadata
greeter-28a0d7a1-4a26-499d-bd9f-364151021f50    10.0.0.1:57647  broker=http,protocol=grpc,registry=mdns,server=grpc,transport=grpc

Endpoint: Greeter.Hello

Request: {
        message_state MessageState {
                no_unkeyed_literals NoUnkeyedLiterals
                do_not_compare DoNotCompare
                do_not_copy DoNotCopy
                message_info MessageInfo
        }
        int32 int32
        unknown_fields []uint8
        name string
}

Response: {
        message_state MessageState {
                no_unkeyed_literals NoUnkeyedLiterals
                do_not_compare DoNotCompare
                do_not_copy DoNotCopy
                message_info MessageInfo
        }
        int32 int32
        unknown_fields []uint8
        greeting string
}

注意到Address地址为10.0.0.1:57647，也就是micro注册到默认网段去了，所以导致服务不可达。

• 带指定server_address参数启动server

go run helloworld/services/server.go --server_address=localhost:8888

• 再次client请求

go run helloworld/services/client.go

这次返回正常结果

Hello John

•  再次查看指定服务信息

micro get service greeter

ID      Address Metadata
greeter-f875a030-436a-420d-a29a-a66249d22381    127.0.0.1:8888  protocol=grpc,registry=mdns,server=grpc,transport=grpc,broker=http

•  服务调用

仿照官网给出的例子

micro call greeter Greeter.Hello '{"name": "John"}' 

不管是PowerShell还是CMD都会报 invalid character 的错误。

需要将"进行转义\"，才可以正常执行，注意PowerShell和CMD的不同

使用consul做服务发现

如果非要使用consul的话，就得往client.go和server.go的import中添加

_ "github.com/micro/go-plugins/registry/consul/v2"

•  启动Consul agent的开发模式

consul agent -dev

• 启动server

go run helloworld/services/server.go --registry=consul --server_address=localhost:8888

• client请求

go run helloworld/services/client.go --registry=consul