go微服务初探--基于go-micro框架构建一个简单的微服务接口以etcd为注册中心

etcd版本:etcd-v3.3.25

etcd节点:
192.168.0.50:2379
192.168.0.51:2379
192.168.0.52:2379

etcd启动配置文件:
 config.yaml 
name: consul01
data-dir: /usr/local/etcd-v3.3.25/data
listen-client-urls: http://192.168.0.50:2379,http://127.0.0.1:2379
advertise-client-urls: http://192.168.0.50:2379,http://127.0.0.1:2379
listen-peer-urls: http://192.168.0.50:2380
initial-advertise-peer-urls: http://192.168.0.50:2380
initial-cluster: consul01=http://192.168.0.50:2380,consul02=http://192.168.0.51:2380,consul03=http://192.168.0.52:2380
initial-cluster-token: etcd-cluster-token
initial-cluster-state: new


etcd启动脚本:

service.sh 
#!/bin/bash

#cd /usr/local/etcd-v3.3.25;nohup ./etcd --config-file config.yaml &
DIR=/usr/local/etcd-v3.3.25
cd $DIR
echo "================ start etcd server================="
PID=`ps aux |grep etcd |grep "config.yaml" |grep -v grep|awk -F " " '{print $2}'`
if [ $PID > 0 ];then
   echo " etcd service is already running!"
   exit 0
fi

nohup ./etcd --config-file config.yaml 1>>./start.log 2>&1  &
stat=$?
if [ $stat == 0 ]
then
   pid=`ps aux |grep etcd |grep "config.yaml" |grep -v grep|awk -F " " '{print $2}'`
   if [ $pid > 0 ]; then
      echo "etcd service start success, pid:$pid"
   else
      echo "etcd service start fail"
   fi
   exit 0
else
  echo "etcd server start failed"
fi

etcdctl 命令：
ETCDCTL_API=3 ./etcdctl --endpoints=http://0:2379,http://1:2379,http://2:2379 endpoint status --write-out=table
etcd 版本为 3.4，可以ETCDCTL_API=3，或ETCDCTL_API=2，默认情况下用的就是v3了，可以不用声明ETCDCTL_API


version: 查看版本
member list: 查看节点状态，learner 情况
endpoint status: 节点状态，leader 情况
endpoint health: 健康状态与耗时
alarm list: 查看警告，如存储满时会切换为只读，产生 alarm
alarm disarm：清除所有警告
set app demo: 写入
get app: 获取
update app demo1:更新
rm app: 删除
mkdir demo 创建文件夹
rmdir dir 删除文件夹
backup 备份
compaction： 压缩
defrag：整理碎片
watch key 监测 key 变化
get / –prefix –keys-only: 查看所有 key
–write-out= tables，可以用表格形式输出更清晰，注意有些输出并不支持tables

目录结构：
tree .
.
├── client
│   └── main.go
├── go.mod
├── go.sum
├── proto
│   └── hello
│       ├── hello.pb.go
│       ├── hello.pb.micro.go
│       └── hello.proto
└── server
    └── main.go

go.mod文件信息如下：
module mehelloword

go 1.14
replace google.golang.org/grpc => google.golang.org/grpc v1.26.0
require (
	github.com/golang/protobuf v1.4.3
	github.com/micro/go-micro v1.18.0
	google.golang.org/protobuf v1.25.0
)

服务接口声明
mkdir proto/hello -p && cd proto/hello

hello.proto
syntax = "proto3";

// protoc -I. --go_out=. --micro_out=.  proto/hello/hello.proto

package mehello;

service Lemon{
    rpc SayHi(Request) returns (Response) {};
}

message Request{
    string name = 1;
    string address = 2;
}

message Response {
    string ret = 1;
}

如上述代码所示，我们定义了一个名为 Lemon 的服务，该服务中包含一个 SayHi 方法，该方法接收一个 Request 对象，然后返回一个 Response 对象.

通过服务声明生成原型代码
protoc -I. --go_out=. --micro_out=.  proto/hello/hello.proto

编写服务实现代码
接下来，我们就可以在项目根目录下创建server/main.go，然后基于上述服务原型代码来编写第一个微服务服务端接口了：
package main

import (
	"context"
	"fmt"
	mehello "mehelloword/proto/hello"

	"github.com/micro/go-micro"
)

type LemonService struct {
}

func (l *LemonService) SayHi(ctx context.Context,
	in *mehello.Request, rsp *mehello.Response) error {
	rsp.Ret = "你好," + in.Name + ", welcome to " + in.Address
	return nil
}

//go run main.go --registry=etcd --registry_address 192.168.0.50:2379
//etcd查查询所有key:./etcdctl  --endpoints="http://192.168.0.51:2379" get  / –prefix –keys-only
//ETCDCTL_API=3 ./etcdctl --endpoints="" --cacert /etc/etcd/ssl/ca.pem
//--cert /etc/etcd/ssl/etcd.pem --key /etc/etcd/ssl/etcd-key.pem endpoint status --write-out=table
//etcd 版本为 3.4，可以ETCDCTL_API=3，或ETCDCTL_API=2，默认情况下用的就是v3了，可以不用声明ETCDCTL_API
func main() {
	//注册一个新的服务
	service := micro.NewService(micro.Name("LemonService"), micro.Address("192.168.0.103:9091"))
	//service init
	service.Init()
	//registry handler and call LemonService's method
	err := mehello.RegisterLemonHandler(service.Server(), new(LemonService))
	if err != nil {
		fmt.Printf("register handler failed,err:%v\n", err)
		return
	}

	//start service
	if err := service.Run(); err != nil {
		panic(err)
	}
	/**
	下面错误解决方案:
	# github.com/coreos/etcd/clientv3/balancer/picker
	../../../pkg/mod/github.com/coreos/etcd@v3.3.17+incompatible/clientv3/balancer/picker/err.go:37:44: undefined: balancer.PickOptions
	../../../pkg/mod/github.com/coreos/etcd@v3.3.17+incompatible/clientv3/balancer/picker/roundrobin_balanced.go:55:54: undefined: balancer.PickOptions
	# github.com/coreos/etcd/clientv3/balancer/resolver/endpoint
	../../../pkg/mod/github.com/coreos/etcd@v3.3.17+incompatible/clientv3/balancer/resolver/endpoint/endpoint.go:114:78: undefined: resolver.BuildOption

	go.mod加下配置:
	replace google.golang.org/grpc v1.27.0 => google.golang.org/grpc v1.26.0

	或:
	replace google.golang.org/grpc => google.golang.org/grpc v1.26.0
	*/
}

//启动服务(如果不指定注册中心，默认使用mdcn)
go run main.go --registry=etcd --registry_address 192.168.0.50:2379
2020-12-15 11:46:37.526713 I | Transport [http] Listening on 192.168.0.103:9091
2020-12-15 11:46:37.527120 I | Broker [http] Connected to [::]:57848
2020-12-15 11:46:37.527166 I | Registry [etcd] Registering node: LemonService-60b77ea5-ecc2-412f-8c58-061cc7930b8b

客户端调用
我们来编写一段简单的客户端测试代码，在项目根目录下创建client/main.go 并编写代码如下：

package main

import (
	"context"
	"fmt"
	mehello "mehelloword/proto/hello"

	"github.com/micro/go-micro"
)

func main() {

	//make a service
	service := micro.NewService(micro.Name("LemonService.Client")) // micro.Address("192.168.0.103:9091")
	//service init
	service.Init()
	//make lemon client
	lemon := mehello.NewLemonService("LemonService", service.Client())
	//call
	rsp, err := lemon.SayHi(context.Background(), &mehello.Request{Name: "柠檬君", Address: "西安"})

	if err != nil {
		panic(err)
	}

	fmt.Printf("ret:%v\n", rsp.Ret)
	fmt.Println(rsp)
}

//运行客户端
 go run main.go --registry=etcd --registry_address 192.168.0.50:2379
ret:你好,柠檬君, welcome to 西安
ret:"你好,柠檬君, welcome to 西安"