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.runnerrunner = 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。能够更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 displayexcept 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: [e-mail]## this is the Interface package of Ansible2 API#from collections import namedtuplefrom ansible.parsing.dataloader import DataLoaderfrom ansible.vars import VariableManagerfrom ansible.inventory import Inventoryfrom ansible.playbook.play import Playfrom ansible.executor.task_queue_manager import TaskQueueManagerfrom tempfile import NamedTemporaryFileimport osclass 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。

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。