flag标志位，标识位，在其他语言中可能叫开关，个人觉得当作开关更容易理解。下面我们来利用这个开关来控制文件操作的流程，从而优雅的修改配置文件。
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 原配置文件
haproxy原配置文件
我们的需求是：
1、实现fetch获取内容的功能
2、往配置文件中指定位置插入内容的功能
3、删除（或者修改）参数
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
}
} 需求
代码需求
思路梳理：
1）定义fetch（）函数，函数内容为打开haproxy配置文件，找到backend开头的行，打开开关，找到第二backend开头的行，关闭开关，将开关开启状态下的行添加到我们定义的空列表中。
def fetch(a):
result=[]
flag = False
with open('ha.conf','r')as f:
for line in f:
if line.strip()=='backend %s'%a:
flag=True
continue
if flag==True:
if line.strip().startswith('backend'):
flag=False
else:
result.append(line.strip())
return result
ret=fetch('www.oldboy.org')
print(ret)
fetch函数
2）定义add（）函数：
方法一：把内容添加进列表，然后把列表内容写入。
# a=input('请输入网址：')
# a='www.oldboy.org'
# b=input('请输入新纪录字典：')
b='{"backend":"www.oldboy.org","record":{"server":"100.1.7.6","weight":20,"maxconn":30}}'
b=json.loads(b)
a=b["backend"]
s=b["record"]
s="server %s %s weight %s maxconn %s" % (s['server'],s['server'],s['weight'],s['maxconn'])
title='backend %s' % a
l1=chaxun(a)
l1.append(s)
print(l1)
with open('mm') as read_obj, open('nn', 'w') as write_obj:
flag = False #默认没有找到目标标题
has_write = False #默认列表内容还没有写
for line in read_obj:
if line.strip() == title:
write_obj.write(line)
flag = True #找到标题
continue
if flag and line.strip().startswith('backend'):
flag = False #标题结束
if flag: #如果已经找到目标标题
if not has_write: #如果还没有写内容
for new_line in l1:
temp = "%s %s \n" %(" "*8, new_line)
write_obj.write(temp)
has_write = True
#列表内容书写完毕，即使flag=True，即使没遇到下一个backend，也不会书写内容
else:
# 写入上下部分
write_obj.write(line)# a=input('请输入网址：')
# a='www.oldboy.org'
# b=input('请输入新纪录字典：')
b='{"backend":"www.oldboy.org","record":{"server":"100.1.7.6","weight":20,"maxconn":30}}'
b=json.loads(b)
a=b["backend"]
s=b["record"]
s="server %s %s weight %s maxconn %s" % (s['server'],s['server'],s['weight'],s['maxconn'])
title='backend %s' % a
l1=chaxun(a)
l1.append(s)
print(l1)
with open('mm') as read_obj, open('nn', 'w') as write_obj:
flag = False #默认没有找到目标标题
has_write = False #默认列表内容还没有写
for line in read_obj:
if line.strip() == title:
write_obj.write(line)
flag = True #找到标题
continue
if flag and line.strip().startswith('backend'):
flag = False #标题结束
if flag: #如果已经找到目标标题
if not has_write: #如果还没有写内容
for new_line in l1:
temp = "%s %s \n" %(" "*8, new_line)
write_obj.write(temp)
has_write = True
#列表内容书写完毕，即使flag=True，即使没遇到下一个backend，也不会书写内容
else:
# 写入上下部分
write_obj.write(line)
add函数列表写入
方法二：读一行，写一行，直到写到第二个backend，再此之前插入内容即可。
# a=input('请输入网址：')
# a='www.oldboy.org'
# b=input('请输入新纪录字典：')
b='{"backend":"www.oldboy.org","record":{"server":"100.1.7.6","weight":20,"maxconn":30}}'
b=json.loads(b)
a=b["backend"]
s=b["record"]
s="server %s %s weight %s maxconn %s" % (s['server'],s['server'],s['weight'],s['maxconn'])
title='backend %s' % a
l1=chaxun(a)
l1.append(s)
print(l1)
with open('mm') as read_obj, open('nn', 'w') as write_obj:
flag = False #默认没有找到目标标题
for line in read_obj:
if line.strip() == title:
write_obj.write(line)
flag = True #找到标题
continue
if flag and line.strip().startswith('backend'):
write_obj.write("%s%s \n" %(" "*8, s))
write_obj.write(line)
flag = False #标题结束
else:
# 写入上下部分
write_obj.write(line)
add函数边读边写
整体实现功能，武sir的标准答案：
#!/usr/bin/env python
# -*- coding:utf-8 -*-
import json
import os def fetch(backend):
backend_title = 'backend %s' % backend
record_list = []
with open('ha') as obj:
flag = False
for line in obj:
line = line.strip()
if line == backend_title:
flag = True
continue
if flag and line.startswith('backend'):
flag = False
break if flag and line:
record_list.append(line) return record_list def add(dict_info):
backend = dict_info.get('backend')
record_list = fetch(backend)
backend_title = "backend %s" % backend
current_record = "server %s %s weight %d maxconn %d" % (dict_info['record']['server'], dict_info['record']['server'], dict_info['record']['weight'], dict_info['record']['maxconn'])
if not record_list:
record_list.append(backend_title)
record_list.append(current_record)
with open('ha') as read_file, open('ha.new', 'w') as write_file:
flag = False
for line in read_file:
write_file.write(line)
for i in record_list:
if i.startswith('backend'):
write_file.write(i+'\n')
else:
write_file.write("%s%s\n" % (8*" ", i))
else:
record_list.insert(0, backend_title)
if current_record not in record_list:
record_list.append(current_record) with open('ha') as read_file, open('ha.new', 'w') as write_file:
flag = False
has_write = False
for line in read_file:
line_strip = line.strip()
if line_strip == backend_title:
flag = True
continue
if flag and line_strip.startswith('backend'):
flag = False
if not flag:
write_file.write(line)
else:
if not has_write:
for i in record_list:
if i.startswith('backend'):
write_file.write(i+'\n')
else:
write_file.write("%s%s\n" % (8*" ", i))
has_write = True
os.rename('ha','ha.bak')
os.rename('ha.new','ha') def remove(dict_info):
backend = dict_info.get('backend')
record_list = fetch(backend)
backend_title = "backend %s" % backend
current_record = "server %s %s weight %d maxconn %d" % (dict_info['record']['server'], dict_info['record']['server'], dict_info['record']['weight'], dict_info['record']['maxconn'])
if not record_list:
return
else:
if current_record not in record_list:
return
else:
del record_list[record_list.index(current_record)]
if len(record_list) > 0:
record_list.insert(0, backend_title)
with open('ha') as read_file, open('ha.new', 'w') as write_file:
flag = False
has_write = False
for line in read_file:
line_strip = line.strip()
if line_strip == backend_title:
flag = True
continue
if flag and line_strip.startswith('backend'):
flag = False
if not flag:
write_file.write(line)
else:
if not has_write:
for i in record_list:
if i.startswith('backend'):
write_file.write(i+'\n')
else:
write_file.write("%s%s\n" % (8*" ", i))
has_write = True
os.rename('ha','ha.bak')
os.rename('ha.new','ha') if __name__ == '__main__':
"""
print '1、获取；2、添加；3、删除'
num = raw_input('请输入序号：')
data = raw_input('请输入内容：')
if num == '1':
fetch(data)
else:
dict_data = json.loads(data)
if num == '2':
add(dict_data)
elif num == '3':
remove(dict_data)
else:
pass
"""
#data = "www.oldboy.org"
#fetch(data)
#data = '{"backend": "tettst.oldboy.org","record":{"server": "100.1.7.90","weight": 20,"maxconn": 30}}'
#dict_data = json.loads(data)
#add(dict_data)
#remove(dict_data) demo
整体代码