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 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。

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。