Golang使用http协议实现心跳检测程序过程详解

package main
import (
	"encoding/json"
	"github.com/hako/durafmt"
	"log"
	"net/http"
	"time"
)
const NotAvailableMessage = "Not available"
var CommitHash string
var StartTime time.Time
type HeartbeatMessage struct {
	Status string `json:"status"`
	Build  string `json:"build"`
	Uptime string `json:"uptime"`
}
func init() {
	StartTime = time.Now()
}
func handler(rw http.ResponseWriter, r *http.Request) {
	hash := CommitHash
	if hash == "" {
		hash = NotAvailableMessage
	}
	df, _ := durafmt.ParseString(time.Since(StartTime).String())
	uptime := df.String()
	err := json.NewEncoder(rw).Encode(HeartbeatMessage{"running", hash, uptime})
	if err != nil {
		log.Fatalf("Failed to write heartbeat message. Reason: %s", err.Error())
	}
}
func RunHeartbeatService(address string) {
	http.HandleFunc("/heartbeat", handler)
	log.Println(http.ListenAndServe(address, nil))
}

func handler(rw http.ResponseWriter, r *http.Request) {
	hash := CommitHash
	if hash == "" {
		hash = NotAvailableMessage
	}
	df, _ := durafmt.ParseString(time.Since(StartTime).String())
	uptime := df.String()
	err := json.NewEncoder(rw).Encode(HeartbeatMessage{"running", hash, uptime})
	if err != nil {
		log.Fatalf("Failed to write heartbeat message. Reason: %s", err.Error())
	}
}

func RunHeartbeatService(address string) {
	http.HandleFunc("/heartbeat", handler)
	log.Println(http.ListenAndServe(address, nil))
}

func main() {
	go RunHeartbeatService(":9090")
	// 阻塞主程序，模拟应用一直在运行
	select {}
}

func Get(address string) (HeartbeatMessage, error) {
	// 定义http client
	client := &http.Client{}
	req, err := http.NewRequest("GET", address, nil)
	resp, err := client.Do(req)
	if err != nil {
		return HeartbeatMessage{}, err
	}
	// 解析响应并返回结果
	b, err := io.ReadAll(resp.Body)
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return HeartbeatMessage{}, errors.New(fmt.Sprintf("Wrong status code: %d", resp.StatusCode))
	}
	message := HeartbeatMessage{}
	err = json.Unmarshal(b, &message)
	if err != nil {
		log.Println("Error occured unmarshalling the response")
	}
	return message, nil
}

package main
import (
	"fmt"
	"testing"
)
func TestGet(t *testing.T) {
	hs, err := Get("http://localhost:9090/heartbeat")
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(hs)
}