consul基礎使用練習

想像去郵局辦事，consul類似於發號碼牌的那個機器

伺服端(櫃台人員)去找consul註冊服務，比如說櫃台1~3提供儲蓄，櫃台4~6提供郵寄服務

客戶進來透過服務發現，把要辦的事丟給consul，它查看哪個櫃台健康，幫你匹配對應的服務或叫號

(感覺這例子不太完善，就…類似的理解啦，實際用了才會懂)

下載

# 官網:
https://www.consul.io/downloads
# ubuntu shell: (下載>解壓縮>把二進位執行檔丟進去)
wget https://releases.hashicorp.com/consul/1.10.3/consul_1.10.3_linux_amd64.zip
unzip consul_1.10.3_linux_amd64.zip
sudo mv consul /usr/local/bin/

測試
```
consul -h
```

啟動server

consul agent -server -bootstrap-expect 1 -data-dir /tmp/consul -node=n1 -bind=192.168.234.128 -ui -rejoin -config-dir=/etc/consul.d/ -client 0.0.0.0

這個IP=192.168.234.128=ubuntu的ip

*若/etc/consul.d/不存在要先自己創

查看服務
```
http://192.168.234.128:8500/
```

註冊自訂的健康檢查服務，範例:

剛剛自訂的配置檔路徑/etc/consul.d/下新增一個web.json

{"service": {
    "name": "web",
    "tags": ["extract", "verify", "compare", "idcard"],
    "address": "192.168.234.128",
    "port": 9000,
    "check": {
        "id": "api",
        "name": "HTTP API on port 9000",
        "http": "http://localhost:9000",
        "interval": "10s",
        "timeout": "1s"
        }
   }
}

重啟server並查看服務
- 結果是不健康，因為沒有東西回應它

透過consul來傳遞一個簡單服務案例:

person.proto

syntax="proto3";
package pb;
option go_package="/.;pb";
message Person{
    string name=1;
    int32 age=2;
}

service hello{
    rpc sayHello(Person) returns(Person);
}

server

package main

import (
	"context"
	"fmt"

	"github.com/hashicorp/consul/api"
	"github.com/my/repo/consul/pb"
)

type Children struct {
}

// 綁定方法實現接口
func (c *Children) SayHello(ctx context.Context, p *pb.Person) (*pb.Person, error) {
	p.Name = "hello" + p.Name
	return p, nil
}

func main() {
	// 1. 把grpc註冊到consul，初始化
	consulConfig := api.DefaultConfig()

	// 2. 創建consul對象
	consulClient, err := api.NewClient(consulConfig)
	if err != nil {
		fmt.Println("api.NewClient err", err)
		return
	}

	// 3. 告訴consul將要註冊的服務消息
	reg := api.AgentServiceRegistration{
		ID:      "bj38",
		Tags:    []string{"grpc", "consul"},
		Name:    "grpc And Consul",
		Address: "127.0.0.1",
		Port:    8800,
		Check: &api.AgentServiceCheck{
			CheckID:  "consul grpc test",
			TCP:      "127.0.0.1:8800",
			Timeout:  "1s",
			Interval: "5s",
		},
	}
	// 4. 註冊到consul上
	consulClient.Agent().ServiceRegister(&reg)
	fmt.Println("服務啟動...")

}

client

package main

import (
	"context"
	"fmt"
	"strconv"

	"github.com/hashicorp/consul/api"
	"github.com/my/repo/consul/pb"
	"google.golang.org/grpc"
)

func main() {
	// 初始化consul
	consulConfig := api.DefaultConfig()
	consulClient, err := api.NewClient(consulConfig)
	if err != nil {
		fmt.Println("api.NewClient err", err)
	}

	// 服務發現，從consul上獲取健康的服務
	services, _, err := consulClient.Health().Service("grpc And Consul", "grpc", true, nil)
	if err != nil {
		fmt.Println("consulClient.Health().Service err", err)
		return
	}
	// 拼接出服務的IP跟端口
	fmt.Println(services[0].Service.Address)
	fmt.Println(services[0].Service.Port)
	addr := services[0].Service.Address + ":" + strconv.Itoa(services[0].Service.Port)

	grpcConn, _ := grpc.Dial(addr, grpc.WithInsecure())

	grpcClient := pb.NewHelloClient(grpcConn)
	var person pb.Person
	person.Name = "Tom~"
	person.Age = 18

	p, err := grpcClient.SayHello(context.TODO(), &person)
	fmt.Println(p, err)

}

記得隨便用個cmd 開啟consul當橋梁

$ consul agent -dev

上次修改於 2021-09-28