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new module: sysctl to handle sysctl entry

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sysctl now capable to search for sys entry into /sys if not under /proc/sys

module/sysctl rolling back to 0.5

write sysctl.conf safely, tempfile first, atomic replace after.
See comments in  https://github.com/ansible/ansible/pull/1810

Patch to replace .format with % () to handle python-2.4 ,
See also https://github.com/ansible/ansible/pull/1810

using name instead key for default arg name. key putted as alias.
also, val become an alias of value arg name.
See also : https://github.com/ansible/ansible/pull/1810
This commit is contained in:
davixx 2012-12-31 19:17:47 +01:00
parent b54bb2dfed
commit 8efa62b0ea
1 changed files with 313 additions and 0 deletions
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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 handle the entries in C(/etc/sysctl.conf),
and perform a I(/sbin/sysctl -p) after any change
version_added: "0.6"
options:
name:
description:
- also known as "key",
this is the short path, point separated to the sysctl entry eg: C(vm.swappiness)"
required: true
default: null
aliases: [ 'key' ]
value:
description:
- "value to affect to the sysctl entry, to not provide if state=absent"
required: false
default: null
aliases: [ 'val' ]
state:
description:
- state=present the entry is added if not exist, or updated if exist
state=absent the entry is removed if exist
choices: [ "present", "absent" ]
default: present
checks:
description:
- C(checks)=I(none) no smart/facultative checks will be made
C(checks)=I(before) some checks performed before any update (ie. does the sysctl key is writable ?)
C(checks)=I(after) some checks performed after an update (ie. does kernel give back the setted value ?)
C(checks)=I(both) all the smart checks I(before and after) are performed
choices: [ "none", "before", "after", "both" ]
default: both
reload:
description:
- C(reload=yes) perform a I(/sbin/sysctl -p) if C(sysctl_file) updated !
C(reload=no) do not reload I(sysctl) even if C(sysctl_file) updated !
choices: [ yes, no ]
default: yes
sysctl_file:
description:
- specify the absolute path to C(/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
# ==============================================================
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):
# key_path
sysctl_args['key_path'] = sysctl_args['name'].replace('.' ,'/')
sysctl_args['key_path'] = '/proc/sys/' + sysctl_args['key_path'];
# end
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'
# sysctl file exists and openable ?
# TODO choose if prefered to use os.access() instead try/catch on open
if current_step == 'before':
try:
with open(sysctl_args['sysctl_file']) as f: pass
except IOError as e:
return 1, 'unable to open supplied sysctl.conf'
# 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:
with open(sysctl_args['key_path'],'r') as f:
output = f.read()
output = output.strip(' \t\n\r')
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)
# 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()