Merge pull request #1810 from davixx/sysctl
new module: sysctl to handle sysctl entry
This commit is contained in:
Michael DeHaan
commit
e7223760c4
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library/sysctl
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313
library/sysctl
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#!/usr/bin/python
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# -*- coding: utf-8 -*-
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# (c) 2012, David "DaviXX" CHANIAL <david.chanial@gmail.com>
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#
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# This file is part of Ansible
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#
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# Ansible is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Ansible is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
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#
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DOCUMENTATION = '''
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---
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module: sysctl
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short_description: Permit to handle sysctl.conf entries
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description:
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- This module handle the entries in C(/etc/sysctl.conf),
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and perform a I(/sbin/sysctl -p) after any change
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version_added: "0.6"
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options:
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name:
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description:
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- also known as "key",
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this is the short path, point separated to the sysctl entry eg: C(vm.swappiness)"
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required: true
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default: null
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aliases: [ 'key' ]
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value:
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description:
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- "value to affect to the sysctl entry, to not provide if state=absent"
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required: false
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default: null
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aliases: [ 'val' ]
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state:
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description:
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- state=present the entry is added if not exist, or updated if exist
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state=absent the entry is removed if exist
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choices: [ "present", "absent" ]
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default: present
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checks:
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description:
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- C(checks)=I(none) no smart/facultative checks will be made
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C(checks)=I(before) some checks performed before any update (ie. does the sysctl key is writable ?)
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C(checks)=I(after) some checks performed after an update (ie. does kernel give back the setted value ?)
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C(checks)=I(both) all the smart checks I(before and after) are performed
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choices: [ "none", "before", "after", "both" ]
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default: both
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reload:
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description:
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- C(reload=yes) perform a I(/sbin/sysctl -p) if C(sysctl_file) updated !
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C(reload=no) do not reload I(sysctl) even if C(sysctl_file) updated !
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choices: [ yes, no ]
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default: yes
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sysctl_file:
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description:
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- specify the absolute path to C(/etc/sysctl.conf)
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required: false
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default: /etc/sysctl.conf
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examples:
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- code: "sysctl: name=vm.swappiness value=5 state=present"
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description: "Set vm.swappiness to 5 in /etc/sysctl.conf"
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- code: "sysctl: name=kernel.panic state=absent sysctl_file=/etc/sysctl.conf"
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description: "Remove kernel.panic entry from /etc/sysctl.conf"
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- code: "sysctl: name=kernel.panic value=3 sysctl_file=/tmp/test_sysctl.conf check=before reload=no"
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description: Set kernel.panic to 3 in /tmp/test_sysctl.conf, check if the sysctl key seems writable, but do not reload sysctl, and do not check kernel value after (not needed, because not the real /etc/sysctl.conf updated)
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notes: []
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requirements: []
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author: David "DaviXX" CHANIAL <david.chanial@gmail.com>
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'''
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# ==============================================================
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import os
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import tempfile
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# ==============================================================
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def reload_sysctl(**sysctl_args):
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# update needed ?
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if not sysctl_args['reload']:
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return 0, ''
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# do it
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cmd = [ '/sbin/sysctl', '-p' ]
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call = subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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out, err = call.communicate()
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if call.returncode == 0:
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return 0, ''
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else:
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return call.returncode, out+err
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# ==============================================================
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def write_sysctl(module, lines, **sysctl_args):
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# open a tmp file
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fd, tmp_path = tempfile.mkstemp('.conf', '.ansible_m_sysctl_', os.path.dirname(sysctl_args['sysctl_file']))
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f = open(tmp_path,"w")
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try:
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for l in lines:
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f.write(l)
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except IOError, e:
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module.fail_json(msg="Failed to write to file %s: %s" % (tmp_path, str(e)))
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f.flush()
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f.close()
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# replace the real one
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module.atomic_replace(tmp_path, sysctl_args['sysctl_file'])
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# end
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return sysctl_args
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# ==============================================================
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def sysctl_args_expand(**sysctl_args):
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# key_path
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sysctl_args['key_path'] = sysctl_args['name'].replace('.' ,'/')
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sysctl_args['key_path'] = '/proc/sys/' + sysctl_args['key_path'];
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# end
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return sysctl_args
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# ==============================================================
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def sysctl_args_collapse(**sysctl_args):
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# go ahead
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if sysctl_args.get('key_path') is not None:
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del sysctl_args['key_path']
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if sysctl_args['state'] == 'absent' and 'value' in sysctl_args:
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del sysctl_args['value']
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# end
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return sysctl_args
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# ==============================================================
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def sysctl_check(current_step, **sysctl_args):
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# checking coherence
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if sysctl_args['state'] == 'absent' and sysctl_args['value'] is not None:
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return 1, 'value=x must not be supplied when state=absent'
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if sysctl_args['state'] == 'present' and sysctl_args['value'] is None:
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return 1, 'value=x must be supplied when state=present'
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if not sysctl_args['reload'] and sysctl_args['checks'] in ['after', 'both']:
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return 1, 'checks cannot be set to after or both if reload=no'
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# getting file stat
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if not os.access(sysctl_args['key_path'], os.F_OK):
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return 1, 'key_path is not an existing file, key seems invalid'
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if not os.access(sysctl_args['key_path'], os.R_OK):
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return 1, 'key_path is not a readable file, key seems to be uncheckable'
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# sysctl file exists and openable ?
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# TODO choose if prefered to use os.access() instead try/catch on open
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if current_step == 'before':
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try:
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with open(sysctl_args['sysctl_file']) as f: pass
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except IOError as e:
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return 1, 'unable to open supplied sysctl.conf'
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# no smart checks at this step ?
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if sysctl_args['checks'] == 'none':
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return 0, ''
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if current_step == 'before' and sysctl_args['checks'] not in ['before', 'both']:
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return 0, ''
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if current_step == 'after' and sysctl_args['checks'] not in ['after', 'both']:
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return 0, ''
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# checks before
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if current_step == 'before' and sysctl_args['checks'] in ['before', 'both']:
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if not os.access(sysctl_args['key_path'], os.W_OK):
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return 1, 'key_path is not a writable file, key seems to be read only'
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return 0, ''
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# checks after
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if current_step == 'after' and sysctl_args['checks'] in ['after', 'both']:
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if sysctl_args['value'] is not None:
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with open(sysctl_args['key_path'],'r') as f:
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output = f.read()
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output = output.strip(' \t\n\r')
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if output != sysctl_args['value']:
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return 1, 'key seems not set to value even after update/sysctl, founded : <%s>, wanted : <%s>' % (output, sysctl_args['value'])
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return 0, ''
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# weird end
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return 1, 'unexpected position reached'
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# ==============================================================
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# main
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def main():
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# defining module
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module = AnsibleModule(
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argument_spec = dict(
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name = dict(aliases=['key'], required=True),
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value = dict(aliases=['val'], required=False),
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state = dict(default='present', choices=['present', 'absent']),
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checks = dict(default='both', choices=['none', 'before', 'after', 'both']),
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reload = dict(default=True, choices=BOOLEANS),
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sysctl_file = dict(default='/etc/sysctl.conf')
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)
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)
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# defaults
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sysctl_args = {
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'changed': False,
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'name': module.params['name'],
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'state': module.params['state'],
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'checks': module.params['checks'],
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'reload': module.boolean(module.params.get('reload', True)),
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'value': module.params.get('value'),
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'sysctl_file': module.params['sysctl_file']
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}
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# prepare vars
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sysctl_args = sysctl_args_expand(**sysctl_args)
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new_line = "%s = %s\n" % (sysctl_args['name'], sysctl_args['value'])
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to_write = []
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founded = False
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# make checks before act
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res,msg = sysctl_check('before', **sysctl_args)
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if res != 0:
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module.fail_json(msg='checks_before failed with: ' + msg)
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# reading the file
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for line in open(sysctl_args['sysctl_file'], 'r').readlines():
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if not line.strip():
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to_write.append(line)
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continue
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if line.strip().startswith('#'):
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to_write.append(line)
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continue
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if len(line.split('=')) != 2:
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# not sure what this is or why it is here
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# but it is not our fault so leave it be
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to_write.append(line)
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continue
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# write line if not the one searched
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ld = {}
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ld['name'], ld['val'] = line.split('=')
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ld['name'] = ld['name'].strip()
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if ld['name'] != sysctl_args['name']:
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to_write.append(line)
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continue
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# should be absent ?
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if sysctl_args['state'] == 'absent':
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# not writing the founded line
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# mark as changed
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sysctl_args['changed'] = True
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# should be present
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if sysctl_args['state'] == 'present':
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# is the founded line equal to the wanted one ?
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ld['val'] = ld['val'].strip()
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if ld['val'] == sysctl_args['value']:
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# line is equal, writing it without update (but cancel repeats)
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if sysctl_args['changed'] == False and founded == False:
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to_write.append(line)
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founded = True
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else:
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# update the line (but cancel repeats)
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if sysctl_args['changed'] == False and founded == False:
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to_write.append(new_line)
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sysctl_args['changed'] = True
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continue
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# if not changed, but should be present, so we have to add it
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if sysctl_args['state'] == 'present' and sysctl_args['changed'] == False and founded == False:
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to_write.append(new_line)
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sysctl_args['changed'] = True
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# has changed ?
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res = 0
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if sysctl_args['changed'] == True:
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sysctl_args = write_sysctl(module, to_write, **sysctl_args)
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res,msg = reload_sysctl(**sysctl_args)
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# make checks after act
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res,msg = sysctl_check('after', **sysctl_args)
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if res != 0:
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module.fail_json(msg='checks_after failed with: ' + msg)
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# look at the next link to avoid this workaround
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# https://groups.google.com/forum/?fromgroups=#!topic/ansible-project/LMY-dwF6SQk
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changed = sysctl_args['changed']
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del sysctl_args['changed']
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# end
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sysctl_args = sysctl_args_collapse(**sysctl_args)
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module.exit_json(changed=changed, **sysctl_args)
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sys.exit(0)
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# this is magic, see lib/ansible/module_common.py
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#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
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main()
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