REMOTE EXECUTION

Posted 2020-10-05 孤独的海浪

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暂略

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STRINGS AND UNICODE

字符编码问题
python2使用的unicode编码，python3使用str字符串。

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OUTPUTTER CONFIGURATION

执行模块能够返回不同格式的数据，salt可以为单个函数指定输出类型，譬如yaml，json等。

__outputter__是一个函数名和对应输出类型的字典，支持的输出类型参考链接：
https://docs.saltstack.com/en/2016.11/ref/output/all/index.html#all-salt-output

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VIRTUAL MODULES

虚拟模块，可以重写一个已经存在的模块。

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__VIRTUAL__ FUNCTION

__VIRTUAL__会返回一个字符串，譬如True, False，如果返回TRUE，则使用当前模块名称加载模块，如果返回false，则不会加载模块。
在模块被加载之后__virtual__被调用，在这个时间点__salt__将不可用。

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RETURNING ERROR INFORMATION FROM __VIRTUAL__

从__VIRTUAL__里面获取错误信息
示例：

 1 ‘‘‘
 2 Cheese execution (or returner/beacon/etc.) module
 3 ‘‘‘
 4 try:
 5     import enzymes
 6     HAS_ENZYMES = True
 7 except ImportError:
 8     HAS_ENZYMES = False
 9 
10 
11 def __virtual__():
12     ‘‘‘
13     only load cheese if enzymes are available
14     ‘‘‘
15     if HAS_ENZYMES:
16         return ‘cheese‘
17     else:
18         return False, ‘The cheese execution module cannot be loaded: enzymes unavailable.‘
19 
20 ‘‘‘
21 Cheese state module
22 ‘‘‘
23 
24 def __virtual__():
25     ‘‘‘
26     only load cheese if enzymes are available
27     ‘‘‘
28     # predicate loading of the cheese state on the corresponding execution module
29     if ‘cheese.slice‘ in __salt__:
30         return ‘cheese‘
31     else:
32         return False, ‘The cheese state module cannot be loaded: enzymes unavailable.‘

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OVERRIDING VIRTUAL MODULE PROVIDERS

在minion端定义被重写后的模块，这样就覆盖了salt本身提供的模块：

1 providers:
2   service: systemd
3   pkg: aptpkg

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虚拟模块的列表：
　　https://docs.saltstack.com/en/2016.11/ref/modules/all/salt.modules.pkg.html#virtual-pkg

 

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__VIRTUALNAME__ 

__virtualname__是一个变量，可以重新定义模块名。
示例：

 1 # Define the module‘s virtual name
 2 __virtualname__ = ‘pkg‘
 3 
 4 
 5 def __virtual__():
 6     ‘‘‘
 7     Confine this module to Mac OS with Homebrew.
 8     ‘‘‘
 9 
10     if salt.utils.which(‘brew‘) and __grains__[‘os‘] == ‘MacOS‘:
11         return __virtualname__
12     return False

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DOCUMENTATION

salt ‘*‘ sys.doc #查看minion端的可用模块

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ADDING DOCUMENTATION TO SALT MODULES

在模块中添加使用帮助文档，这应该是作为一种规范的存在。

示例：

1 def spam(eggs):
2     ‘‘‘
3     A function to make some spam with eggs!
4 
5     CLI Example::
6 
7         salt ‘*‘ test.spam eggs
8     ‘‘‘
9     return eggs

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ADD EXECUTION MODULE METADATA

增加模块的说明文档，设置一个较好的规范格式来展示

1 :maintainer:    Thomas Hatch <[e-mail], Seth House <[email protected]>
2 :maturity:      new
3 :depends:       python-mysqldb
4 :platform:      all

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LOG OUTPUT

调用日志模块，打印日志.

1 log = logging.getLogger(__name__)
2 
3 log.info(‘Here is Some Information‘)
4 log.warning(‘You Should Not Do That‘)
5 log.error(‘It Is Busted‘)

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ALIASING FUNCTIONS

设置模块函数的别名:

1 __func_alias__ = {
2     ‘set_‘: ‘set‘,
3     ‘list_‘: ‘list‘,
4 }

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PRIVATE FUNCTIONS

定义私有函数，以_下划线开头的函数

这样的函数会被加载到minion端:

1 def foo(bar):
2     return bar

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而下面的就不会，python中定义私有方法就是以_开头的:

1 def _foobar(baz): # Preceded with an _
2     return baz
3 
4 cheese = {} # Not a callable Python object

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USEFUL DECORATORS FOR MODULES

在函数中使用装饰器.

示例：

 1 import logging
 2 
 3 from salt.utils.decorators import depends
 4 
 5 log = logging.getLogger(__name__)
 6 
 7 try:
 8     import dependency_that_sometimes_exists
 9 except ImportError as e:
10     log.trace(‘Failed to import dependency_that_sometimes_exists: {0}‘.format(e))
11 
12 @depends(‘dependency_that_sometimes_exists‘)
13 def foo():
14     ‘‘‘
15     Function with a dependency on the "dependency_that_sometimes_exists" module,
16     if the "dependency_that_sometimes_exists" is missing this function will not exist
17     ‘‘‘
18     return True
19 
20 def _fallback():
21     ‘‘‘
22     Fallback function for the depends decorator to replace a function with
23     ‘‘‘
24     return ‘"dependency_that_sometimes_exists" needs to be installed for this function to exist‘
25 
26 @depends(‘dependency_that_sometimes_exists‘, fallback_function=_fallback)
27 def foo():
28     ‘‘‘
29     Function with a dependency on the "dependency_that_sometimes_exists" module.
30     If the "dependency_that_sometimes_exists" is missing this function will be
31     replaced with "_fallback"
32     ‘‘‘
33     return True
34 
35 
36 from salt.utils.decorators import depends
37 
38 HAS_DEP = False
39 try:
40     import dependency_that_sometimes_exists
41     HAS_DEP = True
42 except ImportError:
43     pass
44 
45 @depends(HAS_DEP)
46 def foo():
47     return True

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