5.修改haproxy配置文件

　需求：

 1、查
     输入：www.oldboy.org
     获取当前backend下的所有记录

 2、新建
     输入：
         arg = {
             'backend': 'www.oldboy.org',
             'record':{
                 'server': '100.1.7.9',
                 'weight': 20,
                 'maxconn': 30
             }
         }

 3、删除
     输入：
         arg = {
             'backend': 'www.oldboy.org',
             'record':{
                 'server': '100.1.7.9',
                 'weight': 20,
                 'maxconn': 30
             }
         }

haproxy.cfg配置文件

 global
         log 127.0.0.1 local2
         daemon
         maxconn 256
         log 127.0.0.1 local2 info
 defaults
         log global
         mode http
         timeout connect 5000ms
         timeout client 50000ms
         timeout server 50000ms
         option  dontlognull

 listen stats :8888
         stats enable
         stats uri       /admin
         stats auth      admin:1234

 frontend oldboy.org
         bind 0.0.0.0:80
         option httplog
         option httpclose
         option  forwardfor
         log global
         acl www hdr_reg(host) -i www.oldboy.org
         use_backend www.oldboy.org if www

 backend www.oldboy.org
         server 100.1.7.9 100.1.7.9 weight 20 maxconn 3000

简易流程图：

 # -*- coding:utf-8 -*-
 # Author: JACK ZHAO

 #菜单列表
 operation_list = ["Search haproxy.cfg backend information","Add haproxy.cfg backend information",\
                   "Delete haproy.cfg backend information"]
 #状态判断标志
 flag_search = 0
 flag_add = 0

 while True:
     flag_search = 0
     print(" Haproy configuration file management ".center(50, "#"))
     for index,i in enumerate(operation_list): #遍历菜单列表
         print([index],i)
     choice = input("Please enter your choice[Q:exit]:")
     if choice.isdigit(): #判读输入是否为整数
         choice = int(choice)
         if choice >= 0 and choice <= 2: #判读选择是否在菜单对应的数字内
             if choice == 0: #查询backend information
                 url = input("Please enter URL Address:")
                 with open("haproxy.cfg","r",encoding="utf-8") as f_search: #打开haproxy.cfg一次性读取到内存中
                     for line in f_search:
                         if flag_search == 1:
                             if  "backend" in line:
                                 flag_search = 0
                                 continue
                             else:
                                 if len(line) <= 1: #不打印空白行
                                     continue
                                 else:
                                     print("\033[32;1m%s\033[0m" % line.strip()) #打印符合条件的行，并去掉前后空格、换行符
                                     continue
                         if "backend %s"%url in line and "use_backend" not in line :
                             flag_search = 1
             elif choice == 1: #新增backend information
                 arg = input("Pleas enter backend:")
                 dic_add = eval('''%s'''%arg) #将输入的字符串转成字典
                 with open("haproxy.cfg", "a+", encoding="utf-8") as f_add:
                     f_add.seek(0) #将位置光标移动开始位置,a+模式默认光标在文件最后
                     for line in f_add:
                         if  dic_add["backend"] in line and "use_backend" not in line: #判读backend 是否已经存在
                             print("\033[31;1m%s is exists.\033[0m" %dic_add["backend"])
                             flag_add =1
                             break
                     if flag_add == 1:
                         continue
                     f_add.write("\nbackend %s\n" %dic_add["backend"])
                     f_add.write("\t\tserver %s weight %s maxconn %s\n" % (dic_add["record"]["server"],\
                                     dic_add["record"]["weight"],dic_add["record"]["maxconn"]))
             elif choice == 2:
                 arg = input("Pleas enter backend:")
                 dic_delete = eval('''%s''' % arg) #将输入的字符串转为字典格式
                 with open("haproxy.cfg", "r", encoding='utf-8') as f_delete:
                     lines = f_delete.readlines()
                 with open("haproxy.cfg", "w", encoding='utf-8') as f_delete: #覆盖源文件的方式删除内容
                     for line in lines:
                         if "backend %s" %dic_delete["backend"] in line or "server %s weight %s maxconn %s"\
                             %(dic_delete["record"]["server"],dic_delete["record"]["weight"],dic_delete["record"]["maxconn"]) in line:
                             continue
                         f_delete.write(line)
         else:
             print("It's only going to be 0 to 2.") #必须是菜单对应的数字
             continue
     elif choice == "Q": #选择退出
         exit()
     else:
         print("It has to be an integer.")