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ansible/clustering/consul

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#!/usr/bin/python
#
# (c) 2015, Steve Gargan <steve.gargan@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: consul
short_description: "Add, modify & delete services within a consul cluster.
See http://conul.io for more details."
description:
- registers services and checks for an agent with a consul cluster. A service
is some process running on the agent node that should be advertised by
consul's discovery mechanism. It may optionally supply a check definition
that will be used to notify the consul cluster of the health of the service.
Checks may also be registered per node e.g. disk usage, or cpu usage and
notify the health of the entire node to the cluster.
Service level checks do not require a check name or id as these are derived
by Consul from the Service name and id respectively by appending 'service:'.
Node level checks require a check_name and optionally a check_id Currently,
there is no complete way to retrieve the script, interval or ttl metadata for
a registered check. Without this metadata it is not possible to tell if
the data supplied with ansible represents a change to a check. As a result
this does not attempt to determine changes and will always report a changed
occurred. An api method is planned to supply this metadata so at that stage
change management will be added.
version_added: "1.9"
author: Steve Gargan (steve.gargan@gmail.com)
options:
state:
description:
- register or deregister the consul service, defaults to present
required: true
choices: ['present', 'absent']
service_id:
description:
- the ID for the service, must be unique per node, defaults to the
service name
required: false
host:
description:
- host of the consul agent with which to register the service,
defaults to localhost
required: false
notes:
description:
- Notes to attach to check when registering it.
service_name:
desciption:
- Unique name for the service on a node, must be unique per node,
required if registering a service. May be ommitted if registering
a node level check
required: false
service_port:
description:
- the port on which the service is listening required for
registration of a service.
required: true
tags:
description:
- a list of tags that will be attached to the service registration.
required: false
script:
description:
- the script/command that will be run periodically to check the health
of the service
required: false
interval:
description:
- the interval at which the service check will be run. This is by
convention a number with a s or m to signify the units of seconds
or minutes. if none is supplied, m will be appended
check_id:
description:
- an ID for the service check, defaults to the check name, ignored if
part of service definition.
check_name:
description:
- a name for the service check, defaults to the check id. required if
standalone, ignored if part of service definition.
"""
EXAMPLES = '''
- name: register nginx service with the local consul agent
consul:
name: nginx
port: 80
- name: register nginx service with curl check
consul:
name: nginx
port: 80
script: "curl http://localhost"
interval: 60s
- name: register nginx with some service tags
consul:
name: nginx
port: 80
tags:
- prod
- webservers
- name: remove nginx service
consul:
name: nginx
state: absent
- name: create a node level check to test disk usage
consul:
check_name: Disk usage
check_id: disk_usage
script: "/opt/disk_usage.py"
interval: 5m
'''
import sys
import urllib2
try:
import json
except ImportError:
import simplejson as json
try:
import consul
except ImportError, e:
print "failed=True msg='python-consul required for this module. "\
"see http://python-consul.readthedocs.org/en/latest/#installation'"
sys.exit(1)
def register_with_consul(module):
state = module.params.get('state')
if state == 'present':
add(module)
else:
remove(module)
def add(module):
''' adds a service or a check depending on supplied configuration'''
check = parse_check(module)
service = parse_service(module)
if not service and not check:
module.fail_json(msg='a name and port are required to register a service')
if service:
if check:
service.add_check(check)
add_service(module, service)
elif check:
add_check(module, check)
def remove(module):
''' removes a service or a check '''
service_id = module.params.get('service_id') or module.params.get('service_name')
check_id = module.params.get('check_id') or module.params.get('check_name')
if not (service_id or check_id):
module.fail_json(msg='services and checks are removed by id or name.'\
' please supply a service id/name or a check id/name')
if service_id:
remove_service(module, service_id)
else:
remove_check(module, check_id)
def add_check(module, check):
''' registers a check with the given agent. currently there is no way
retrieve the full metadata of an existing check through the consul api.
Without this we can't compare to the supplied check and so we must assume
a change. '''
if not check.name:
module.fail_json(msg='a check name is required for a node level check,'\
' one not attached to a service')
consul_api = get_consul_api(module)
check.register(consul_api)
module.exit_json(changed=True,
check_id=check.check_id,
check_name=check.name,
script=check.script,
interval=check.interval,
ttl=check.ttl)
def remove_check(module, check_id):
''' removes a check using its id '''
consul_api = get_consul_api(module)
if check_id in consul_api.agent.checks():
consul_api.agent.check.deregister(check_id)
module.exit_json(changed=True, id=check_id)
module.exit_json(changed=False, id=check_id)
def add_service(module, service):
''' registers a service with the the current agent '''
result = service
changed = False
consul_api = get_consul_api(module)
existing = get_service_by_id(consul_api, service.id)
# there is no way to retreive the details of checks so if a check is present
# in the service it must be reregistered
if service.has_checks() or not existing or not existing == service:
service.register(consul_api)
# check that it registered correctly
registered = get_service_by_id(consul_api, service.id)
if registered:
result = registered
changed = True
module.exit_json(changed=changed,
service_id=result.id,
service_name=result.name,
service_port=result.port,
checks=map(lambda x: x.to_dict(), service.checks),
tags=result.tags)
def remove_service(module, service_id):
''' deregister a service from the given agent using its service id '''
consul_api = get_consul_api(module)
service = get_service_by_id(consul_api, service_id)
if service:
consul_api.agent.service.deregister(service_id)
module.exit_json(changed=True, id=service_id)
module.exit_json(changed=False, id=service_id)
def get_consul_api(module, token=None):
return consul.Consul(host=module.params.get('host'),
port=module.params.get('port'),
token=module.params.get('token'))
def get_service_by_id(consul_api, service_id):
''' iterate the registered services and find one with the given id '''
for name, service in consul_api.agent.services().iteritems():
if service['ID'] == service_id:
return ConsulService(loaded=service)
def parse_check(module):
if module.params.get('script') and module.params.get('ttl'):
module.fail_json(
msg='check are either script or ttl driven, supplying both does'\
' not make sense')
if module.params.get('check_id') or module.params.get('script') or module.params.get('ttl'):
return ConsulCheck(
module.params.get('check_id'),
module.params.get('check_name'),
module.params.get('check_node'),
module.params.get('check_host'),
module.params.get('script'),
module.params.get('interval'),
module.params.get('ttl'),
module.params.get('notes')
)
def parse_service(module):
if module.params.get('service_name') and module.params.get('service_port'):
return ConsulService(
module.params.get('service_id'),
module.params.get('service_name'),
module.params.get('service_port'),
module.params.get('tags'),
)
elif module.params.get('service_name') and not module.params.get('service_port'):
module.fail_json(
msg="service_name supplied but no service_port, a port is required"\
" to configure a service. Did you configure the 'port' "\
"argument meaning 'service_port'?")
class ConsulService():
def __init__(self, service_id=None, name=None, port=-1,
tags=None, loaded=None):
self.id = self.name = name
if service_id:
self.id = service_id
self.port = port
self.tags = tags
self.checks = []
if loaded:
self.id = loaded['ID']
self.name = loaded['Service']
self.port = loaded['Port']
self.tags = loaded['Tags']
def register(self, consul_api):
if len(self.checks) > 0:
check = self.checks[0]
consul_api.agent.service.register(
self.name,
service_id=self.id,
port=self.port,
tags=self.tags,
script=check.script,
interval=check.interval,
ttl=check.ttl)
else:
consul_api.agent.service.register(
self.name,
service_id=self.id,
port=self.port,
tags=self.tags)
def add_check(self, check):
self.checks.append(check)
def checks(self):
return self.checks
def has_checks(self):
return len(self.checks) > 0
def __eq__(self, other):
return (isinstance(other, self.__class__)
and self.id == other.id
and self.name == other.name
and self.port == other.port
and self.tags == other.tags)
def __ne__(self, other):
return not self.__eq__(other)
def to_dict(self):
data = {'id': self.id, "name": self.name}
if self.port:
data['port'] = self.port
if self.tags and len(self.tags) > 0:
data['tags'] = self.tags
if len(self.checks) > 0:
data['check'] = self.checks[0].to_dict()
return data
class ConsulCheck():
def __init__(self, check_id, name, node=None, host='localhost',
script=None, interval=None, ttl=None, notes=None):
self.check_id = self.name = name
if check_id:
self.check_id = check_id
self.script = script
self.interval = str(interval)
if not self.interval.endswith('m') or self.interval.endswith('s'):
self.interval += 'm'
self.ttl = ttl
self.notes = notes
self.node = node
self.host = host
if interval and interval <= 0:
raise Error('check interval must be positive')
if ttl and ttl <= 0:
raise Error('check ttl value must be positive')
def register(self, consul_api):
consul_api.agent.check.register(self.name, check_id=self.check_id,
script=self.script,
interval=self.interval,
ttl=self.ttl, notes=self.notes)
def __eq__(self, other):
return (isinstance(other, self.__class__)
and self.check_id == other.check_id
and self.name == other.name
and self.script == script
and self.interval == interval)
def __ne__(self, other):
return not self.__eq__(other)
def to_dict(self):
data = {}
self._add(data, 'id', attr='check_id')
self._add(data, 'name', attr='check_name')
self._add(data, 'script')
self._add(data, 'node')
self._add(data, 'notes')
self._add(data, 'host')
self._add(data, 'interval')
self._add(data, 'ttl')
return data
def _add(self, data, key, attr=None):
try:
if attr == None:
attr = key
data[key] = getattr(self, attr)
except:
pass
def main():
module = AnsibleModule(
argument_spec=dict(
check_id=dict(required=False),
check_name=dict(required=False),
host=dict(default='localhost'),
interval=dict(required=False, default='1m'),
check_node=dict(required=False),
check_host=dict(required=False),
notes=dict(required=False),
port=dict(default=8500, type='int'),
script=dict(required=False),
service_id=dict(required=False),
service_name=dict(required=False),
service_port=dict(required=False, type='int'),
state=dict(default='present', choices=['present', 'absent']),
tags=dict(required=False, type='list'),
token=dict(required=False),
url=dict(default='http://localhost:8500')
),
supports_check_mode=False,
)
try:
register_with_consul(module)
except IOError, e:
error = e.read()
if not error:
error = str(e)
module.fail_json(msg=error)
# import module snippets
from ansible.module_utils.basic import *
main()
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