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 = {
            'bakend': 'www.oldboy.org',
            'record':{
                'server': '100.1.7.9',
                'weight': 20,
                'maxconn': 30
            }
        }

3、删除
    输入：
        arg = {
            'bakend': 'www.oldboy.org',
            'record':{
                'server': '100.1.7.9',
                'weight': 20,
                'maxconn': 30
            }
        }
分析：
1、输入是字典模式的字符串，需要把字符串转换为字典，对字典进行处理
2、对文件进行copy，读取，覆盖写操作，还要设置标志，进行区分处理
3、函数的调用

功能查：

def fetch(backend):
    #取出backend相关的server信息
    result = [] #定义结果列表
    with open("haproxy","r",encoding="utf-8") as f: #循环读取文件
        flag = False  #标记为假
        for line in f :
            #以backend开头
            line = line.strip()
            if line.startswith("backend") and line == "backend %s" %backend:
                flag = True  #读取到backend开头的信息，标记为真
                continue   #直接返回到for语句
            #如果遇到下一个backend开头的语句，直接break跳出for语句，因为数据拿完了
            if flag and line.startswith("backend"):
                flag = False
                break
            #server信息添加到result列表
            if flag and line.strip():
                result.append(line)
    return result

实现代码：

import shutil
import json

def list_function():
    print("Please choice the ID of a action.".center(50,"#"))# 50g个字符，提示在中间，不够的#补足
    print("【1】.Fetch haproxy backend infomation.")
    print("【2】.Add haproxy backend infomation.")
    print("【3】.Delete haproxy backend infomation.")
    print("【q】.Delete haproxy backend infomation.")
def fetch(backend):
    #取出backend相关的server信息
    result = [] #定义结果列表
    with open("haproxy","r",encoding="utf-8") as f: #循环读取文件
        flag = False  #标记为假
        for line in f :
            #以backend开头
            line = line.strip()
            if line.startswith("backend") and line == "backend %s" %backend:
                flag = True  #读取到backend开头的信息，标记为真
                continue   #直接返回到for语句
            #如果遇到下一个backend开头的语句，直接break跳出for语句，因为数据拿完了
            if flag and line.startswith("backend"):
                flag = False
                break
            #server信息添加到result列表
            if flag and line.strip():
                result.append(line)
    return result

def writer(backend,record_list):
    with open("haproxy","r") as old,open("haproxy_new","w") as new:
        flag = False
        for line in old:
            if line == "backend %s
" %backend:
                flag = True
                new.write(line)
                for new_line in record_list:
                    new.write(""*4 + new_line + "
")
                continue
            if flag and line.strip().startswith("backend"):
                flag = False
                new.write(line)
                continue   #跳到下一次循环，防止backend写两次
            if line.strip() and not flag:
                new.write(line)

def add(backend, record):
    global change_flag
    record_list = fetch(backend) #查找是否存在backend
    if not record_list and record_list != []: #backend不存在同时record_list是空列表
        with open('haproxy','r') as old, open("haproxy_new",'w') as new:
            for line in old:
                new.write(line)
            new.write("
backend " + backend + "
")
            new.write(" "*4 + record + "
")
            print("33[32;1mAdd done33[0m")
            change_flag = True
    else:  #backend存在
        if record in record_list:
            print("Record already in it,Nothing to do!")
            change_flag = False
        else: #backend存在，record不存在
            record_list.append(record)
            writer(backend,record_list)
            print("33[32;1mAdd done33[0m")
            change_flag = True

def delete(backend, record):
    global change_flag
    record_list = fetch(backend)
    if not record_list:
        print("Not match the backend,no need delete!".center(50,"#"))
    else:
        if record in record_list:
            record_list.remove(record)
            writer(backend,record_list) #写入
            print("33[31;1mDelete done33[0m")
            change_flag = True
        else: #backend存在，record不存在
            print("Only math backend,no need delete!".center(50,"#"))
            change_flag = False
    return change_flag

def output(servers):
    #输出指定backend的server信息
    print("Match the server info:".center(50,"#"))
    for server in servers:
        print("33[32;1m%s33[0m" % server)
    print("#".center(50,"#"))

def operate(action):
    global change_flag
    if action == "fetch":
        backend_info = input("Input backend info:")
        result = fetch(backend_info) #取出backend信息
        if result:
            output(result) #输出获取到的server信息
        else:
            print("33[31;1mNot a match is found!33[0m")
    elif action is None:
        print("33[31;1mNothing to do!33[0m")
    else:
        backend_record = input("Input backend info(dict):")  # 输入的是字符串,
        backend_record_dict = eval(backend_record)
        backend = backend_record_dict['backend']
        record = backend_record_dict['record']
        record = "server %s %s weight %s maxconn %s" % (record['server'], record['server'],
                                                        record['weight'], record['maxconn'])
        if action == "add":
            add(backend,record)
        elif action == "delete":
            delete(backend,record)
        if change_flag is True:  #文件有修改，才进行文件更新
            shutil.copy("haproxy","haproxy_old")
            shutil.copy("haproxy_new","haproxy")
            result = fetch(backend)
            output(result)  #输出获取到的server信息

def judge_input():
    #判断输入功能编号，执行相应步骤
    input_info = input("Your input number:").strip()
    if input_info == "1":  #查询指定backend记录
        action = "fetch"
    elif input_info == "2":
        action = "add"
    elif input_info == "3":
        action = "delete"
    elif input_info == "q" or input_info == "quit":
        exit("Bye,thanks!".center(50,"#"))
    else:
        print("33[31;1mInput error!33[0m")
        action = None
    return action

def main():
    exit_flag = False
    while exit_flag is not True:
        global change_flag
        change_flag = False
        list_function()
        action = judge_input()
        operate(action)

if __name__ == '__main__':
    main()