优雅重启HTTP服务

  • 目的 1、不关闭现有连接（正在运行中的程序） 2、新的进程启动并替代旧进程 3、新的进程接管新的连接 4、连接要随时响应用户的请求，当用户仍在请求旧进程时要保持连接，新用户应请求新进程，不可以出现拒绝请求的情况

  • 流程 1、替换可执行文件或修改配置文件 2、发送信号量 SIGHUP 3、拒绝新连接请求旧进程，但要保证已有连接正常 4、启动新的子进程 5、新的子进程开始 Accet 6、系统将新的请求转交新的子进程 7、旧进程处理完所有旧连接后正常结束

github.com/fvbock/endless

use the net/http package


package main

import (
	"html/template"
	"log"
	"net/http"
	"os"
	"regexp"
)

type Page struct {
	Title string
	Body  []byte
}

func (p *Page) save() error {
	filename := p.Title + ".txt"
	return os.WriteFile(filename, p.Body, 0600)
}

func loadPage(title string) (*Page, error) {
	filename := title + ".txt"
	body, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	return &Page{Title: title, Body: body}, nil
}

func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
	p, err := loadPage(title)
	if err != nil {
		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
		return
	}
	renderTemplate(w, "view", p)
}

func editHandler(w http.ResponseWriter, r *http.Request, title string) {
	p, err := loadPage(title)
	if err != nil {
		p = &Page{Title: title}
	}
	renderTemplate(w, "edit", p)
}

func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
	body := r.FormValue("body")
	p := &Page{Title: title, Body: []byte(body)}
	err := p.save()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	http.Redirect(w, r, "/view/"+title, http.StatusFound)
}

var templates = template.Must(template.ParseFiles("edit.html", "view.html"))

func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
	err := templates.ExecuteTemplate(w, tmpl+".html", p)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")

func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		m := validPath.FindStringSubmatch(r.URL.Path)
		if m == nil {
			http.NotFound(w, r)
			return
		}
		fn(w, r, m[2])
	}
}

func main() {
	http.HandleFunc("/view/", makeHandler(viewHandler))
	http.HandleFunc("/edit/", makeHandler(editHandler))
	http.HandleFunc("/save/", makeHandler(saveHandler))

	log.Fatal(http.ListenAndServe(":8080", nil))
}