SaltStack源码分析之service模块

/usr/lib/python2.6/site-packages/salt/modules/service.py

-*- coding: utf-8 -*-
'''
The default service module, if not otherwise specified salt will fall back
to this basic module
'''

# Import python libs
import os

__func_alias__ = {
'reload_': 'reload'
}

_GRAINMAP = {
'Arch': '/etc/rc.d',
'Arch ARM': '/etc/rc.d'
}

这里定义两个字典，__func_alias__ 和 _GRAINMAP.

在python中，如果一个变量是以单个下划线开头的话，表示这个变量是私有变量。例如_var。
如果是以两个下划线开头的话，就表示这个变量是严格的私有变量，例如__var 。模块内部访问，外部无法直接调用。
如果是以两个下划线开头和结尾的话，就表示这个变量是python语言级别的变量，如__var__

单个下划线结尾是为了避免与python关键字冲突。如var_

def __virtual__():
'''
Only work on systems which exclusively use sysvinit
'''
# Disable on these platforms, specific service modules exist:
disable = set((
'RedHat',
'CentOS',
'Amazon',
'ScientificLinux',
'CloudLinux',
'Fedora',
'Gentoo',
'Ubuntu',
'Debian',
'Arch',
'Arch ARM',
'ALT',
'SUSE  Enterprise Server',
'OEL',
'Linaro',
'elementary OS',
'McAfee  OS Server'
))
if __grains__.get('os', '') in disable:
return False
# Disable on all non-Linux OSes as well
if __grains__['kernel'] != 'Linux':
return False
# Suse >=12.0 uses systemd
if __grains__.get('os_family', '') == 'Suse':
try:
if int(__grains__.get('osrelease', '').split('.')[0]) >= 12:
return False
except ValueError:
return False
return 'service'

Master在向minion发送命令之前会执行一些操作，例如返回静态grain的值或者动态grain的函数

def start(name):
'''
Start the specified service

CLI Example:

.. code-block:: bash

salt '*' service.start <service name>
'''
cmd = os.path.join(
_GRAINMAP.get(__grains__.get('os'), '/etc/init.d'),
name
) + ' start'
return not __salt__['cmd.retcode'](cmd)

$ sudo salt '*' service.start httpd
jidong-fileserver:
True
localhost.localdomain:
False
gintama-qa-server:
False
jialebi-qa-server:
False

def stop(name):
'''
Stop the specified service

CLI Example:

.. code-block:: bash

salt '*' service.stop <service name>
'''
cmd = os.path.join(
_GRAINMAP.get(__grains__.get('os'), '/etc/init.d'),
name
) + ' stop'
return not __salt__['cmd.retcode'](cmd)

$ sudo salt '*' service.stop httpd
jidong-fileserver:
True
localhost.localdomain:
True
gintama-qa-server:
True
jialebi-qa-server:
True

def restart(name):
'''
Restart the specified service

CLI Example:

.. code-block:: bash

salt '*' service.restart <service name>
'''
cmd = os.path.join(
_GRAINMAP.get(__grains__.get('os'), '/etc/init.d'),
name
) + ' restart'
return not __salt__['cmd.retcode'](cmd)

$ sudo salt '*' service.restart httpd
jidong-fileserver:
True
localhost.localdomain:
False
gintama-qa-server:
False
jialebi-qa-server:
False

def status(name, sig=None):
'''
Return the status for a service, returns the PID or an empty string if the
service is running or not, pass a signature to use to find the service via
ps

CLI Example:

.. code-block:: bash

salt '*' service.status <service name> [service signature]
'''
return __salt__['status.pid'](sig if sig else name)

$ sudo salt '*' service.status httpd
jidong-fileserver:
True
localhost.localdomain:
False
gintama-qa-server:
False
jialebi-qa-server:
False

def reload_(name):
'''
Refreshes config files by calling service reload. Does not perform a full
restart.

CLI Example:

.. code-block:: bash

salt '*' service.reload <service name>
'''
cmd = os.path.join(
_GRAINMAP.get(__grains__.get('os'), '/etc/init.d'),
name
) + ' reload'
return not __salt__['cmd.retcode'](cmd)

$ sudo salt '*' service.reload httpd
jidong-fileserver:
False
localhost.localdomain:
False
gintama-qa-server:
False
jialebi-qa-server:
False

def available(name):
'''
Returns ``True`` if the specified service is available, otherwise returns
``False``.

CLI Example:

.. code-block:: bash

salt '*' service.available sshd
'''
return name in get_all()

$ sudo salt '*' service.available httpd
jidong-fileserver:
True
localhost.localdomain:
True
gintama-qa-server:
True
jialebi-qa-server:
True

def missing(name):
'''
The inverse of service.available.
Returns ``True`` if the specified service is not available, otherwise returns
``False``.

CLI Example:

.. code-block:: bash

salt '*' service.missing sshd
'''
return name not in get_all()

$ sudo salt '*' service.missing httpd
jidong-fileserver:
False
localhost.localdomain:
False
gintama-qa-server:
False
jialebi-qa-server:
False

def get_all():
'''
Return a list of all available services

CLI Example:

.. code-block:: bash

salt '*' service.get_all
'''
if not os.path.isdir(_GRAINMAP.get(__grains__.get('os'), '/etc/init.d')):
return []
return sorted(os.listdir(_GRAINMAP.get(__grains__.get('os'), '/etc/init.d')))

获取所有服务名称

参考资料：
http://docs.saltstack.com/en/latest/topics/development/dunder_dictionaries.html#grains

本文出自 “Linux SA John” 博客，请务必保留此出处http://john88wang.blog.51cto.com/2165294/1650560