ansible/clustering/znode.py

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#!/usr/bin/python
# Copyright 2015 WP Engine, Inc. All rights reserved.
#
# 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: znode
version_added: "2.0"
short_description: Create, delete, retrieve, and update znodes using ZooKeeper.
options:
hosts:
description:
- A list of ZooKeeper servers (format '[server]:[port]').
required: true
path:
description:
- The path of the znode.
required: true
value:
description:
- The value assigned to the znode.
default: None
required: false
op:
description:
- An operation to perform. Mutually exclusive with state.
default: None
required: false
state:
description:
- The state to enforce. Mutually exclusive with op.
default: None
required: false
timeout:
description:
- The amount of time to wait for a node to appear.
default: 300
required: false
requirements:
- kazoo >= 2.1
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- python >= 2.6
author: "Trey Perry (@treyperry)"
"""
EXAMPLES = """
# Creating or updating a znode with a given value
- action: znode hosts=localhost:2181 name=/mypath value=myvalue state=present
# Getting the value and stat structure for a znode
- action: znode hosts=localhost:2181 name=/mypath op=get
# Listing a particular znode's children
- action: znode hosts=localhost:2181 name=/zookeeper op=list
# Waiting 20 seconds for a znode to appear at path /mypath
- action: znode hosts=localhost:2181 name=/mypath op=wait timeout=20
# Deleting a znode at path /mypath
- action: znode hosts=localhost:2181 name=/mypath state=absent
"""
try:
from kazoo.client import KazooClient
from kazoo.exceptions import NoNodeError, ZookeeperError
from kazoo.handlers.threading import KazooTimeoutError
KAZOO_INSTALLED = True
except ImportError:
KAZOO_INSTALLED = False
def main():
module = AnsibleModule(
argument_spec=dict(
hosts=dict(required=True, type='str'),
name=dict(required=True, type='str'),
value=dict(required=False, default=None, type='str'),
op=dict(required=False, default=None, choices=['get', 'wait', 'list']),
state=dict(choices=['present', 'absent']),
timeout=dict(required=False, default=300, type='int')
),
supports_check_mode=False
)
if not KAZOO_INSTALLED:
module.fail_json(msg='kazoo >= 2.1 is required to use this module. Use pip to install it.')
check = check_params(module.params)
if not check['success']:
module.fail_json(msg=check['msg'])
zoo = KazooCommandProxy(module)
try:
zoo.start()
except KazooTimeoutError:
module.fail_json(msg='The connection to the ZooKeeper ensemble timed out.')
command_dict = {
'op': {
'get': zoo.get,
'list': zoo.list,
'wait': zoo.wait
},
'state': {
'present': zoo.present,
'absent': zoo.absent
}
}
command_type = 'op' if 'op' in module.params and module.params['op'] is not None else 'state'
method = module.params[command_type]
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result, result_dict = command_dict[command_type][method]
zoo.shutdown()
if result:
module.exit_json(**result_dict)
else:
module.fail_json(**result_dict)
def check_params(params):
if not params['state'] and not params['op']:
return {'success': False, 'msg': 'Please define an operation (op) or a state.'}
if params['state'] and params['op']:
return {'success': False, 'msg': 'Please choose an operation (op) or a state, but not both.'}
return {'success': True}
class KazooCommandProxy():
def __init__(self, module):
self.module = module
self.zk = KazooClient(module.params['hosts'])
def absent(self):
return self._absent(self.module.params['name'])
def exists(self, znode):
return self.zk.exists(znode)
def list(self):
children = self.zk.get_children(self.module.params['name'])
return True, {'count': len(children), 'items': children, 'msg': 'Retrieved znodes in path.',
'znode': self.module.params['name']}
def present(self):
return self._present(self.module.params['name'], self.module.params['value'])
def get(self):
return self._get(self.module.params['name'])
def shutdown(self):
self.zk.stop()
self.zk.close()
def start(self):
self.zk.start()
def wait(self):
return self._wait(self.module.params['name'], self.module.params['timeout'])
def _absent(self, znode):
if self.exists(znode):
self.zk.delete(znode)
return True, {'changed': True, 'msg': 'The znode was deleted.'}
else:
return True, {'changed': False, 'msg': 'The znode does not exist.'}
def _get(self, path):
if self.exists(path):
value, zstat = self.zk.get(path)
stat_dict = {}
for i in dir(zstat):
if not i.startswith('_'):
attr = getattr(zstat, i)
if type(attr) in (int, str):
stat_dict[i] = attr
result = True, {'msg': 'The node was retrieved.', 'znode': path, 'value': value,
'stat': stat_dict}
else:
result = False, {'msg': 'The requested node does not exist.'}
return result
def _present(self, path, value):
if self.exists(path):
(current_value, zstat) = self.zk.get(path)
if value != current_value:
self.zk.set(path, value)
return True, {'changed': True, 'msg': 'Updated the znode value.', 'znode': path,
'value': value}
else:
return True, {'changed': False, 'msg': 'No changes were necessary.', 'znode': path, 'value': value}
else:
self.zk.create(path, value, makepath=True)
return True, {'changed': True, 'msg': 'Created a new znode.', 'znode': path, 'value': value}
def _wait(self, path, timeout, interval=5):
lim = time.time() + timeout
while time.time() < lim:
if self.exists(path):
return True, {'msg': 'The node appeared before the configured timeout.',
'znode': path, 'timeout': timeout}
else:
time.sleep(interval)
return False, {'msg': 'The node did not appear before the operation timed out.', 'timeout': timeout,
'znode': path}
from ansible.module_utils.basic import *
main()