87 lines
2.7 KiB
Python
87 lines
2.7 KiB
Python
# -*- test-case-name: twisted.python.test.test_systemd -*-
|
|
# Copyright (c) Twisted Matrix Laboratories.
|
|
# See LICENSE for details.
|
|
|
|
"""
|
|
Integration with systemd.
|
|
|
|
Currently only the minimum APIs necessary for using systemd's socket activation
|
|
feature are supported.
|
|
"""
|
|
|
|
__all__ = ['ListenFDs']
|
|
|
|
from os import getpid
|
|
|
|
|
|
class ListenFDs(object):
|
|
"""
|
|
L{ListenFDs} provides access to file descriptors inherited from systemd.
|
|
|
|
Typically L{ListenFDs.fromEnvironment} should be used to construct a new
|
|
instance of L{ListenFDs}.
|
|
|
|
@cvar _START: File descriptors inherited from systemd are always
|
|
consecutively numbered, with a fixed lowest "starting" descriptor. This
|
|
gives the default starting descriptor. Since this must agree with the
|
|
value systemd is using, it typically should not be overridden.
|
|
@type _START: C{int}
|
|
|
|
@ivar _descriptors: A C{list} of C{int} giving the descriptors which were
|
|
inherited.
|
|
"""
|
|
_START = 3
|
|
|
|
def __init__(self, descriptors):
|
|
"""
|
|
@param descriptors: The descriptors which will be returned from calls to
|
|
C{inheritedDescriptors}.
|
|
"""
|
|
self._descriptors = descriptors
|
|
|
|
|
|
@classmethod
|
|
def fromEnvironment(cls, environ=None, start=None):
|
|
"""
|
|
@param environ: A dictionary-like object to inspect to discover
|
|
inherited descriptors. By default, C{None}, indicating that the
|
|
real process environment should be inspected. The default is
|
|
suitable for typical usage.
|
|
|
|
@param start: An integer giving the lowest value of an inherited
|
|
descriptor systemd will give us. By default, C{None}, indicating
|
|
the known correct (that is, in agreement with systemd) value will be
|
|
used. The default is suitable for typical usage.
|
|
|
|
@return: A new instance of C{cls} which can be used to look up the
|
|
descriptors which have been inherited.
|
|
"""
|
|
if environ is None:
|
|
from os import environ
|
|
if start is None:
|
|
start = cls._START
|
|
|
|
descriptors = []
|
|
|
|
try:
|
|
pid = int(environ['LISTEN_PID'])
|
|
except (KeyError, ValueError):
|
|
pass
|
|
else:
|
|
if pid == getpid():
|
|
try:
|
|
count = int(environ['LISTEN_FDS'])
|
|
except (KeyError, ValueError):
|
|
pass
|
|
else:
|
|
descriptors = range(start, start + count)
|
|
del environ['LISTEN_PID'], environ['LISTEN_FDS']
|
|
|
|
return cls(descriptors)
|
|
|
|
|
|
def inheritedDescriptors(self):
|
|
"""
|
|
@return: The configured list of descriptors.
|
|
"""
|
|
return list(self._descriptors)
|