python模板渲染配置文件

python的mako、jinja2模板库，确实好用！这里做个笔记，好记性不如烂笔头。

#!/usr/bin/env python
#encoding=utf-8
import sys,yaml                       # 配置文件使用yaml格式
from mako.template import Template      # 加载mako库的Template Class
from jinja2 import Environment,FileSystemLoader  # 加载jinja2的Environment,FileSystemLoader Class

'''
解析配置文件，返回值是一个dict

'''

def parse_pxe_config(filename):
config = yaml.load(file(filename,'r'))
return config

'''
这个函数实现的功能

举例来说，掩码前缀为27转换为255.255.255.224

'''

def int2mask(mask_str):
mask_int = int(mask_str)
mask_array = ['0' for i in xrange(32)]   # python for循环，吊吧！一口气生成32个list的元素
for i in xrange(mask_int):
mask_array[i] = '1'
temp_mask = [''.join(mask_array[i*8:(i+1)*8]) for i in xrange(4)]   # 每8位组成一个list元素
temp_mask = [str(int(i,2)) for i in temp_mask]    # int(i,2) 二进制转换为十进制
return '.'.join(temp_mask)

'''
根据网关地址和掩码前缀得到管理网网段

'''

def get_manage_net(gateway,prefix_str):
prefix = int(prefix_str)
int2bin = [bin(int(i,10)).split('0b')[1] for i in gateway.split('.')]   # bin(int(i,10)) 十进制转化为二进制
for i in xrange(4):
if len(int2bin[i]) < 8:
int2bin[i] = '0'*(8 - len(int2bin[i])) + int2bin[i]
int2bin = ''.join(int2bin)
int2bin = int2bin[0:prefix]+'0'*(32-prefix)
int2bin_list = [int2bin[8*i:(i+1)*8] for i in xrange(4)]
manage_net = [str(int(i,2)) for i in int2bin_list]
return '.'.join(manage_net)

'''
利用python模板库渲染配置文件

'''

def create_pxe_config(config):
#  读取配置文件中的配置项
system_common = config['system common']
manage_prefix = system_common['manage_prefix']
manage_gateway = system_common['manage_gateway']
manage_mask = int2mask(manage_prefix)
manage_net = get_manage_net(manage_gateway,manage_prefix)
dns = system_common['dns']
fqdn = system_common['fqdn']
repo_url = system_common['repo_url']
password = system_common['password']
manage_nic = system_common['manage_nic']
storage_nic = system_common['storage_nic']
public_nic = system_common['public_nic']
data_nic = system_common['data_nic']
deploy_node = config['deploy node']
deploy_node_ip = deploy_node['ip']
deploy_node_hostname = deploy_node['hostname']
dhcp_range_start = deploy_node['dhcp_range_start']
dhcp_range_end = deploy_node['dhcp_range_end']

compute_node = config['compute node']
dhcp_template = Template(                                         # 创建一个Template对象
filename='./pxe_template/dhcpd.conf',
module_directory='/tmp/mako_modules'      # 为了提高性能，从文件加载的 Template 还可以在文件系统中将生成的模块缓存为一般的Python模块文件，
)                                         # 下次同样参数的Template 创建时，自动重用/tmp/mako_modules/目录下的模块文件。

dhcp_content = dhcp_template.render(                              # 传给 Template 的文本参数被编译为一个Python模块。模块包含一个 render_body() 函数，它产生模板的输出。
manage_gateway = manage_gateway,          # 调用render() 方法时，Mako建立了一个模板的运行环境，并调用 render_body() 函数，把输出保存到缓冲，返回它的字符串内容
dns = dns,
manage_mask = manage_mask,
fqdn = fqdn,
deploy_node_ip = deploy_node_ip,
manage_net = manage_net,
dhcp_range_start = dhcp_range_start,
dhcp_range_end = dhcp_range_end
)
fp = open('./pxe_config/dhcpd.conf','w')     # 生成dhcpd.conf配置文件
fp.write(dhcp_content)
if fp != None:
fp.close()
ip_mac_template = Template(                                         # ip-mac 绑定
filename='./pxe_template/ip_mac.conf',
module_directory='/tmp/mako_modules'
)
for compute in compute_node:
ip_mac_content = ip_mac_template.render(
compute_hostname = compute['hostname'],
manage_mac = compute['manage_mac'],
manage_ip = compute['manage_ip']
)
fp = open('./pxe_config/dhcpd.conf','a')                      # 以append方式打开文件
fp.write('\n'+ip_mac_content)                                 # 追加内容

env = Environment(
loader = FileSystemLoader('./pxe_template')          # 这个类的实例被用于存储配置信息, 全局对象, 从文件系统或其他位置加载模板，使用的加载器loader是FileSystemLoader类型,
)                                                # 可以加载的模板是当前工作目录下的templates目录下的模板文件
ks_template = env.get_template("puppet.cfg")                     # 使用env的模板环境加载名为puppet.cfg的模板文件.
ks_content = ks_template.render(                                 # 渲染模板template
repo_url = repo_url,
password = password,
deploy_node_hostname = deploy_node_hostname,
fqdn = fqdn,
deploy_node_ip = deploy_node_ip,
public_nic = public_nic,
storage_nic = storage_nic,
data_nic = data_nic,
manage_gateway = manage_gateway,
manage_mask = manage_mask
)
fp = file('./pxe_config/puppet.cfg','w')
fp.write(ks_content)

if fp != None:
fp.close()

if __name__ == '__main__':
if len(sys.argv) != 2 or sys.argv[1] != 'config.yaml':
print "Usage:pxe-init.py config.yaml"
sys.exit(-1)
config = parse_pxe_config(sys.argv[1])
create_pxe_config(config)

针对上面代码的改良版，写的不好的地方，欢迎大家指出！

#!/usr/bin/env python
#encoding=utf-8
import sys,yaml
import subprocess                                 # 用来创建一个子进程
from jinja2 import Environment,FileSystemLoader   # 统一使用jinja2模板
env = Environment(
loader = FileSystemLoader('./pxe_template')   # env设为全局变量
)
def parse_pxe_config(filename):
config = yaml.load(file(filename,'r'))
return config
'''
'1'*4 == '1111'
int('111',2) == 7 二进制转换十进制
从<<运算符得出的灵感
'''
def int2mask(prefix):
return '.'.join(str(int(('1'*(int(prefix))+'0' \
*(32-int(prefix)))[i*8:(i+1)*8],2)) \
for i in xrange(4))
'''
使用zip对两个list同时遍历，然后对各个元素进行&运算
192   168  2      254
255   255  255  224
不知道通过ip和mask计算网络号，google下！
'''
def get_manage_net(gateway,prefix_str):
mask = int2mask(int(prefix_str))
return '.'.join(str(int(m) & int(n)) \
for m,n in zip(gateway.split('.'),mask.split('.')))
'''
模板渲染抽象为一个函数
渲染的时候可以传进一个dict搞定，dict的key要和模板中的变量名对应(我老大实验得到的)
'''
def create_config_template(tem_name,tem_dict):
template = env.get_template(tem_name)
content = template.render(tem_dict)
return content
'''
创建配置文件
'''
def create_config_file(config_name,content,mode):
try:
fp = open(config_name,mode)
fp.write(content+'\n')
except IOError:
print "Error: can\'t find file or read data"
else:
fp.close()
'''
这部分内容比上面的搜身了不少吧，当然还有很多地方要改进的！
'''
def create_pxe_config(config):
system_common = config.get('system common')           # 字典使用get方法获取key对应的value，如果key不存在，返回None。比config['system common']友好多了。
manage_prefix = system_common.get('manage_prefix')
manage_gateway = system_common.get('manage_gateway')
manage_mask = int2mask(manage_prefix)
manage_net = get_manage_net(manage_gateway,manage_prefix)

deploy_node = config.get('deploy node')
deploy_node['manage_gateway'] = manage_gateway
deploy_node['manage_mask'] = manage_mask
deploy_node['manage_net'] = manage_net
dhcp_content = create_config_template('dhcpd.conf',deploy_node)
create_config_file('./pxe_config/dhcpd.conf',dhcp_content,'w')
compute_node = config['compute node']
for compute_name,compute_info in compute_node.items():
ip_mac_content = create_config_template("ip_mac.conf",compute_info)
create_config_file('./pxe_config/dhcpd.conf',ip_mac_content,'a')
subprocess.Popen('service dhcpd restart',shell = True)                 # 开了子进程来重启dhcpd服务，好让修改的dhcp配置生效
deploy_node.update(system_common)
ks_content = create_config_template('puppet.cfg',deploy_node)
create_config_file('./pxe_config/puppet.cfg',ks_content,'w')
pxe_default_content = create_config_template('default',system_common)
create_config_file('./pxe_config/default',pxe_default_content,'w')
'''
这部分不变
'''
if __name__ == '__main__':
if len(sys.argv) != 2 or sys.argv[1] != 'config.yaml':
print "Usage:pxe-init.py config.yaml"
sys.exit(-1)
config = parse_pxe_config(sys.argv[1])
create_pxe_config(config)

参考链接
http://www.yeolar.com/note/2012/08/26/mako-usage/

/article/1651987.html

本文出自 “the-way-to-cloud” 博客，请务必保留此出处http://iceyao.blog.51cto.com/9426658/1566384