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如何使用Ansible 2的API做python开发

在ansible1.9的时候,API是一个非常简单的东西。官方说“it’s pretty simple”,真是又pretty又simple。

import ansible.runner  runner = ansible.runner.Runner(    module_name='ping',    module_args='',    pattern='web*',    forks=10 ) datastructure = runner.run()

到了ansible2.0以后,是“a bit more complicated”,Oh my,简直让人难受。

简洁和灵活是鱼和熊掌。

ansible2.0 API怎么用?

ansible2.0更贴近于ansible cli的常用命令执行方式,不同于上一版本只能发送单个命令或playbook;而更推荐用户在调用ansibleAPI的时候,将playbook的每个task拆分出来,获取每个task的结果。能够跟灵活处理在执行批量作业过程中的各种反馈。

  • 将执行操作的队列模型,包含各类环境参数设置,归结到“ansible.executor.task_queue_manager”类中
  • 将执行过程中的各个task的设置,或者说playbook中的编排内容,归结到“ansible.playbook.play”中

上述两个东西,几乎囊括了可以在执行过程中设置的所有参数,足够灵活,也让人抓狂,相当于需要自己写一个1.9版本中的runner。
他们的确也都是原生类,并非专用于外部调用。

ansible.executor.task_queue_manager

这是ansible的一个内部模块(ansible/executor/task_queue_manager.py)。初始化的源码如下:

class TaskQueueManager:      '''     This class handles the multiprocessing requirements of Ansible by     creating a pool of worker forks, a result handler fork, and a     manager object with shared datastructures/queues for coordinating     work between all processes.      The queue manager is responsible for loading the play strategy plugin,     which dispatches the Play's tasks to hosts.     '''      def __init__(self, inventory, variable_manager, loader, options, passwords, stdout_callback=None, run_additional_callbacks=True, run_tree=False):          self._inventory        = inventory         self._variable_manager = variable_manager         self._loader           = loader         self._options          = options         self._stats            = AggregateStats()         self.passwords         = passwords         self._stdout_callback  = stdout_callback         self._run_additional_callbacks = run_additional_callbacks         self._run_tree         = run_tree          self._callbacks_loaded = False         self._callback_plugins = []         self._start_at_done    = False         self._result_prc       = None          ……

创建时,需要的主要参数包括:

  • inventory –> 由ansible.inventory模块创建,用于导入inventory文件
  • variable_manager –> 由ansible.vars模块创建,用于存储各类变量信息
  • loader –> 由ansible.parsing.dataloader模块创建,用于数据解析
  • options –> 存放各类配置信息的数据字典
  • passwords –> 登录密码,可设置加密信息
  • stdout_callback –> 回调函数

ansible.playbook.play

ansible.playbook是一个原生模块,既用于CLI也用于API。从源码可以看出来:

try:     from __main__ import display except ImportError:     from ansible.utils.display import Display     display = Display()

ansible.playbook.play(ansible/playbook/play.py)。初始化源码的介绍如下:

__all__ = ['Play']   class Play(Base, Taggable, Become):      """     A play is a language feature that represents a list of roles and/or     task/handler blocks to execute on a given set of hosts.      Usage:         Play.load(datastructure) -> Play        Play.something(...)     """
  • 最后,用task_queue_manager(play)来执行,老规矩,源码的官方解释。
def run(self, play):         '''         Iterates over the roles/tasks in a play, using the given (or default)         strategy for queueing tasks. The default is the linear strategy, which         operates like classic Ansible by keeping all hosts in lock-step with         a given task (meaning no hosts move on to the next task until all hosts         are done with the current task).         '''

一个完整的例子

# -*- coding:utf-8 -*- # !/usr/bin/env python # # Author: Shawn.T # Email: shawntai.ds@gmail.com # # this is the Interface package of Ansible2 API #  from collections import namedtuple from ansible.parsing.dataloader import DataLoader from ansible.vars import VariableManager from ansible.inventory import Inventory from ansible.playbook.play import Play from ansible.executor.task_queue_manager import TaskQueueManager from tempfile import NamedTemporaryFile import os  class AnsibleTask(object):     def __init__(self, targetHost):         Options = namedtuple(                           'Options', [                               'listtags', 'listtasks', 'listhosts', 'syntax', 'connection','module_path',                               'forks', 'remote_user', 'private_key_file', 'ssh_common_args', 'ssh_extra_args',                               'sftp_extra_args', 'scp_extra_args', 'become', 'become_method', 'become_user',                               'verbosity', 'check'                           ]                        )          # initialize needed objects         self.variable_manager = VariableManager()          self.options = Options(                           listtags=False, listtasks=False, listhosts=False, syntax=False, connection='smart',                           module_path='/usr/lib/python2.7/site-packages/ansible/modules', forks=100,                           remote_user='root', private_key_file=None, ssh_common_args=None, ssh_extra_args=None,                           sftp_extra_args=None, scp_extra_args=None, become=False, become_method=None, become_user='root',                           verbosity=None, check=False                       )         self.passwords = dict(vault_pass='secret')         self.loader = DataLoader()          # create inventory and pass to var manager         self.hostsFile = NamedTemporaryFile(delete=False)         self.hostsFile.write(targetHost)         self.hostsFile.close()         self.inventory = Inventory(loader=self.loader, variable_manager=self.variable_manager, host_list=self.hostsFile.name)         self.variable_manager.set_inventory(self.inventory)      def ansiblePlay(self, action):         # create play with tasks         args = "ls /"         play_source =  dict(                 name = "Ansible Play",                 hosts = 'all',                 gather_facts = 'no',                 tasks = [                     dict(action=dict(module='shell', args=args), register='shell_out'),                     dict(action=dict(module='debug', args=dict(msg='{{shell_out.stdout}}')))                 ]             )         play = Play().load(play_source, variable_manager=self.variable_manager, loader=self.loader)          # run it         tqm = None         try:             tqm = TaskQueueManager(                       inventory=self.inventory,                       variable_manager=self.variable_manager,                       loader=self.loader,                       options=self.options,                       passwords=self.passwords,                       stdout_callback='default',                   )             result = tqm.run(play)         finally:         # print result             if tqm is not None:                 tqm.cleanup()                 os.remove(self.hostsFile.name)                 self.inventory.clear_pattern_cache()             return result

写一个ansibleTask类,创建了上述的各类必要的配置信息对象,最后使用ansibleTask.ansiblePlay()函数执行。

  • inventory文件的动态生成

写上面的代码的过程中,碰到一个问题:inventory对象创建时需要一个实体的hosts文件,而文件需要动态生成。
生成的方法参考了这篇牛逼闪闪的文章。使用tempfile.NamedTemporaryFile这个方法来创建一个有名称的临时文件,可以选择关闭后删除或保留。上面的处理办法是:不删除,在执行完毕之后,通过os.remove(self.hostsFile.name)进行删除。

ps.经YiChenWang指出,inventory的创建参数host_list可以使列表。使用以下方式创建inventory也是可以的:

self.inventory = Inventory(loader=self.loader, variable_manager=self.variable_manager, host_list=['xx.xx.xx.xx', 'xx.xx.xx.xx'])

不过,源码中指出,采用list格式参数是无法加载inventory data的。如果需要加载,还是得使用临时文件的办法。

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