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ansible/library/sysctl
Michel Blanc 6f9d28c8b1 Changed when new sysctl file is created 
When destination sysctl file is missing, it is created.
But, for idempotency purposes, the creation process now takes place just before it is used, in the
main code path so an empty file is not left over if the code
module.fail_jsons before the file is really used.
2013-02-20 12:52:30 +01:00

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#!/usr/bin/python
# -*- coding: utf-8 -*-
# (c) 2012, David "DaviXX" CHANIAL <david.chanial@gmail.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
#
DOCUMENTATION = '''
---
module: sysctl
short_description: Permit to handle sysctl.conf entries
description:
- This module manipulates sysctl entries and performs a I(/sbin/sysctl -p) after changing them.
version_added: "1.0"
options:
name:
description:
- this is the short path, decimal seperated, to the sysctl entry
required: true
default: null
aliases: [ 'key' ]
value:
description:
- set the sysctl value to this entry
required: false
default: null
aliases: [ 'val' ]
state:
description:
- whether the entry should be present or absent
choices: [ "present", "absent" ]
default: present
checks:
description:
- if C(checks)=I(none) no smart/facultative checks will be made
- if C(checks)=I(before) some checks performed before any update (ie. does the sysctl key is writable ?)
- if C(checks)=I(after) some checks performed after an update (ie. does kernel give back the setted value ?)
- if C(checks)=I(both) all the smart checks I(before and after) are performed
choices: [ "none", "before", "after", "both" ]
default: both
reload:
description:
- if C(reload=yes), performs a I(/sbin/sysctl -p) if the C(sysctl_file) is updated
- if C(reload=no), does not reload I(sysctl) even if the C(sysctl_file) is updated
choices: [ yes, no ]
default: yes
sysctl_file:
description:
- specifies the absolute path to C(sysctl.conf), if not /etc/sysctl.conf
required: false
default: /etc/sysctl.conf
examples:
- code: "sysctl: name=vm.swappiness value=5 state=present"
description: "Set vm.swappiness to 5 in /etc/sysctl.conf"
- code: "sysctl: name=kernel.panic state=absent sysctl_file=/etc/sysctl.conf"
description: "Remove kernel.panic entry from /etc/sysctl.conf"
- code: "sysctl: name=kernel.panic value=3 sysctl_file=/tmp/test_sysctl.conf check=before reload=no"
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)
notes: []
requirements: []
author: David "DaviXX" CHANIAL <david.chanial@gmail.com>
'''
# ==============================================================
import os
import tempfile
import re
# ==============================================================
def reload_sysctl(**sysctl_args):
# update needed ?
if not sysctl_args['reload']:
return 0, ''
# do it
cmd = [ '/sbin/sysctl', '-p' ]
call = subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = call.communicate()
if call.returncode == 0:
return 0, ''
else:
return call.returncode, out+err
# ==============================================================
def write_sysctl(module, lines, **sysctl_args):
# open a tmp file
fd, tmp_path = tempfile.mkstemp('.conf', '.ansible_m_sysctl_', os.path.dirname(sysctl_args['sysctl_file']))
f = open(tmp_path,"w")
try:
for l in lines:
f.write(l)
except IOError, e:
module.fail_json(msg="Failed to write to file %s: %s" % (tmp_path, str(e)))
f.flush()
f.close()
# replace the real one
module.atomic_replace(tmp_path, sysctl_args['sysctl_file'])
# end
return sysctl_args
# ==============================================================
def sysctl_args_expand(**sysctl_args):
sysctl_args['key_path'] = sysctl_args['name'].replace('.' ,'/')
sysctl_args['key_path'] = '/proc/sys/' + sysctl_args['key_path']
return sysctl_args
# ==============================================================
def sysctl_args_collapse(**sysctl_args):
# go ahead
if sysctl_args.get('key_path') is not None:
del sysctl_args['key_path']
if sysctl_args['state'] == 'absent' and 'value' in sysctl_args:
del sysctl_args['value']
# end
return sysctl_args
# ==============================================================
def sysctl_check(current_step, **sysctl_args):
# checking coherence
if sysctl_args['state'] == 'absent' and sysctl_args['value'] is not None:
return 1, 'value=x must not be supplied when state=absent'
if sysctl_args['state'] == 'present' and sysctl_args['value'] is None:
return 1, 'value=x must be supplied when state=present'
if not sysctl_args['reload'] and sysctl_args['checks'] in ['after', 'both']:
return 1, 'checks cannot be set to after or both if reload=no'
# getting file stat
if not os.access(sysctl_args['key_path'], os.F_OK):
return 1, 'key_path is not an existing file, key seems invalid'
if not os.access(sysctl_args['key_path'], os.R_OK):
return 1, 'key_path is not a readable file, key seems to be uncheckable'
# no smart checks at this step ?
if sysctl_args['checks'] == 'none':
return 0, ''
if current_step == 'before' and sysctl_args['checks'] not in ['before', 'both']:
return 0, ''
if current_step == 'after' and sysctl_args['checks'] not in ['after', 'both']:
return 0, ''
# checks before
if current_step == 'before' and sysctl_args['checks'] in ['before', 'both']:
if not os.access(sysctl_args['key_path'], os.W_OK):
return 1, 'key_path is not a writable file, key seems to be read only'
return 0, ''
# checks after
if current_step == 'after' and sysctl_args['checks'] in ['after', 'both']:
if sysctl_args['value'] is not None:
# reading the virtual file
f = open(sysctl_args['key_path'],'r')
output = f.read()
f.close()
output = output.strip(' \t\n\r')
output = re.sub(r'\s+', ' ', output)
# multi positive integer values separated by spaces as described in issue #2004 :
if re.search('^([\d\s]+)$', sysctl_args['value']):
# replace all groups of spaces by one space
output = re.sub('(\s+)', ' ', output)
# normal case, finded value must be equal to the submitted value :
if output != sysctl_args['value']:
return 1, 'key seems not set to value even after update/sysctl, founded : <%s>, wanted : <%s>' % (output, sysctl_args['value'])
return 0, ''
# weird end
return 1, 'unexpected position reached'
# ==============================================================
# main
def main():
# defining module
module = AnsibleModule(
argument_spec = dict(
name = dict(aliases=['key'], required=True),
value = dict(aliases=['val'], required=False),
state = dict(default='present', choices=['present', 'absent']),
checks = dict(default='both', choices=['none', 'before', 'after', 'both']),
reload = dict(default=True, choices=BOOLEANS),
sysctl_file = dict(default='/etc/sysctl.conf')
)
)
# defaults
sysctl_args = {
'changed': False,
'name': module.params['name'],
'state': module.params['state'],
'checks': module.params['checks'],
'reload': module.boolean(module.params.get('reload', True)),
'value': module.params.get('value'),
'sysctl_file': module.params['sysctl_file']
}
# prepare vars
sysctl_args = sysctl_args_expand(**sysctl_args)
new_line = "%s = %s\n" % (sysctl_args['name'], sysctl_args['value'])
to_write = []
founded = False
# make checks before act
res,msg = sysctl_check('before', **sysctl_args)
if res != 0:
module.fail_json(msg='checks_before failed with: ' + msg)
if not os.access(sysctl_args['sysctl_file'], os.W_OK):
try:
f = open(sysctl_args['sysctl_file'],'w')
f.write('')
f.close()
except IOError, e:
module.fail_json(msg='unable to create supplied sysctl file (destination directory probably missing)')
# reading the file
for line in open(sysctl_args['sysctl_file'], 'r').readlines():
if not line.strip():
to_write.append(line)
continue
if line.strip().startswith('#'):
to_write.append(line)
continue
if len(line.split('=')) != 2:
# not sure what this is or why it is here
# but it is not our fault so leave it be
to_write.append(line)
continue
# write line if not the one searched
ld = {}
ld['name'], ld['val'] = line.split('=')
ld['name'] = ld['name'].strip()
if ld['name'] != sysctl_args['name']:
to_write.append(line)
continue
# should be absent ?
if sysctl_args['state'] == 'absent':
# not writing the founded line
# mark as changed
sysctl_args['changed'] = True
# should be present
if sysctl_args['state'] == 'present':
# is the founded line equal to the wanted one ?
ld['val'] = ld['val'].strip()
if ld['val'] == sysctl_args['value']:
# line is equal, writing it without update (but cancel repeats)
if sysctl_args['changed'] == False and founded == False:
to_write.append(line)
founded = True
else:
# update the line (but cancel repeats)
if sysctl_args['changed'] == False and founded == False:
to_write.append(new_line)
sysctl_args['changed'] = True
continue
# if not changed, but should be present, so we have to add it
if sysctl_args['state'] == 'present' and sysctl_args['changed'] == False and founded == False:
to_write.append(new_line)
sysctl_args['changed'] = True
# has changed ?
res = 0
if sysctl_args['changed'] == True:
sysctl_args = write_sysctl(module, to_write, **sysctl_args)
res,msg = reload_sysctl(**sysctl_args)
# make checks after act
res,msg = sysctl_check('after', **sysctl_args)
if res != 0:
module.fail_json(msg='checks_after failed with: ' + msg)
# look at the next link to avoid this workaround
# https://groups.google.com/forum/?fromgroups=#!topic/ansible-project/LMY-dwF6SQk
changed = sysctl_args['changed']
del sysctl_args['changed']
# end
sysctl_args = sysctl_args_collapse(**sysctl_args)
module.exit_json(changed=changed, **sysctl_args)
sys.exit(0)
# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()
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