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-# Copyright 2014-2015 Canonical Limited.
-#
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers 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 Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
-
-import os
-import json
-from inspect import getargspec
-from collections import Iterable, OrderedDict
-
-from charmhelpers.core import host
-from charmhelpers.core import hookenv
-
-
-__all__ = ['ServiceManager', 'ManagerCallback',
- 'PortManagerCallback', 'open_ports', 'close_ports', 'manage_ports',
- 'service_restart', 'service_stop']
-
-
-class ServiceManager(object):
- def __init__(self, services=None):
- """
- Register a list of services, given their definitions.
-
- Service definitions are dicts in the following formats (all keys except
- 'service' are optional)::
-
- {
- "service": <service name>,
- "required_data": <list of required data contexts>,
- "provided_data": <list of provided data contexts>,
- "data_ready": <one or more callbacks>,
- "data_lost": <one or more callbacks>,
- "start": <one or more callbacks>,
- "stop": <one or more callbacks>,
- "ports": <list of ports to manage>,
- }
-
- The 'required_data' list should contain dicts of required data (or
- dependency managers that act like dicts and know how to collect the data).
- Only when all items in the 'required_data' list are populated are the list
- of 'data_ready' and 'start' callbacks executed. See `is_ready()` for more
- information.
-
- The 'provided_data' list should contain relation data providers, most likely
- a subclass of :class:`charmhelpers.core.services.helpers.RelationContext`,
- that will indicate a set of data to set on a given relation.
-
- The 'data_ready' value should be either a single callback, or a list of
- callbacks, to be called when all items in 'required_data' pass `is_ready()`.
- Each callback will be called with the service name as the only parameter.
- After all of the 'data_ready' callbacks are called, the 'start' callbacks
- are fired.
-
- The 'data_lost' value should be either a single callback, or a list of
- callbacks, to be called when a 'required_data' item no longer passes
- `is_ready()`. Each callback will be called with the service name as the
- only parameter. After all of the 'data_lost' callbacks are called,
- the 'stop' callbacks are fired.
-
- The 'start' value should be either a single callback, or a list of
- callbacks, to be called when starting the service, after the 'data_ready'
- callbacks are complete. Each callback will be called with the service
- name as the only parameter. This defaults to
- `[host.service_start, services.open_ports]`.
-
- The 'stop' value should be either a single callback, or a list of
- callbacks, to be called when stopping the service. If the service is
- being stopped because it no longer has all of its 'required_data', this
- will be called after all of the 'data_lost' callbacks are complete.
- Each callback will be called with the service name as the only parameter.
- This defaults to `[services.close_ports, host.service_stop]`.
-
- The 'ports' value should be a list of ports to manage. The default
- 'start' handler will open the ports after the service is started,
- and the default 'stop' handler will close the ports prior to stopping
- the service.
-
-
- Examples:
-
- The following registers an Upstart service called bingod that depends on
- a mongodb relation and which runs a custom `db_migrate` function prior to
- restarting the service, and a Runit service called spadesd::
-
- manager = services.ServiceManager([
- {
- 'service': 'bingod',
- 'ports': [80, 443],
- 'required_data': [MongoRelation(), config(), {'my': 'data'}],
- 'data_ready': [
- services.template(source='bingod.conf'),
- services.template(source='bingod.ini',
- target='/etc/bingod.ini',
- owner='bingo', perms=0400),
- ],
- },
- {
- 'service': 'spadesd',
- 'data_ready': services.template(source='spadesd_run.j2',
- target='/etc/sv/spadesd/run',
- perms=0555),
- 'start': runit_start,
- 'stop': runit_stop,
- },
- ])
- manager.manage()
- """
- self._ready_file = os.path.join(hookenv.charm_dir(), 'READY-SERVICES.json')
- self._ready = None
- self.services = OrderedDict()
- for service in services or []:
- service_name = service['service']
- self.services[service_name] = service
-
- def manage(self):
- """
- Handle the current hook by doing The Right Thing with the registered services.
- """
- hookenv._run_atstart()
- try:
- hook_name = hookenv.hook_name()
- if hook_name == 'stop':
- self.stop_services()
- else:
- self.reconfigure_services()
- self.provide_data()
- except SystemExit as x:
- if x.code is None or x.code == 0:
- hookenv._run_atexit()
- hookenv._run_atexit()
-
- def provide_data(self):
- """
- Set the relation data for each provider in the ``provided_data`` list.
-
- A provider must have a `name` attribute, which indicates which relation
- to set data on, and a `provide_data()` method, which returns a dict of
- data to set.
-
- The `provide_data()` method can optionally accept two parameters:
-
- * ``remote_service`` The name of the remote service that the data will
- be provided to. The `provide_data()` method will be called once
- for each connected service (not unit). This allows the method to
- tailor its data to the given service.
- * ``service_ready`` Whether or not the service definition had all of
- its requirements met, and thus the ``data_ready`` callbacks run.
-
- Note that the ``provided_data`` methods are now called **after** the
- ``data_ready`` callbacks are run. This gives the ``data_ready`` callbacks
- a chance to generate any data necessary for the providing to the remote
- services.
- """
- for service_name, service in self.services.items():
- service_ready = self.is_ready(service_name)
- for provider in service.get('provided_data', []):
- for relid in hookenv.relation_ids(provider.name):
- units = hookenv.related_units(relid)
- if not units:
- continue
- remote_service = units[0].split('/')[0]
- argspec = getargspec(provider.provide_data)
- if len(argspec.args) > 1:
- data = provider.provide_data(remote_service, service_ready)
- else:
- data = provider.provide_data()
- if data:
- hookenv.relation_set(relid, data)
-
- def reconfigure_services(self, *service_names):
- """
- Update all files for one or more registered services, and,
- if ready, optionally restart them.
-
- If no service names are given, reconfigures all registered services.
- """
- for service_name in service_names or self.services.keys():
- if self.is_ready(service_name):
- self.fire_event('data_ready', service_name)
- self.fire_event('start', service_name, default=[
- service_restart,
- manage_ports])
- self.save_ready(service_name)
- else:
- if self.was_ready(service_name):
- self.fire_event('data_lost', service_name)
- self.fire_event('stop', service_name, default=[
- manage_ports,
- service_stop])
- self.save_lost(service_name)
-
- def stop_services(self, *service_names):
- """
- Stop one or more registered services, by name.
-
- If no service names are given, stops all registered services.
- """
- for service_name in service_names or self.services.keys():
- self.fire_event('stop', service_name, default=[
- manage_ports,
- service_stop])
-
- def get_service(self, service_name):
- """
- Given the name of a registered service, return its service definition.
- """
- service = self.services.get(service_name)
- if not service:
- raise KeyError('Service not registered: %s' % service_name)
- return service
-
- def fire_event(self, event_name, service_name, default=None):
- """
- Fire a data_ready, data_lost, start, or stop event on a given service.
- """
- service = self.get_service(service_name)
- callbacks = service.get(event_name, default)
- if not callbacks:
- return
- if not isinstance(callbacks, Iterable):
- callbacks = [callbacks]
- for callback in callbacks:
- if isinstance(callback, ManagerCallback):
- callback(self, service_name, event_name)
- else:
- callback(service_name)
-
- def is_ready(self, service_name):
- """
- Determine if a registered service is ready, by checking its 'required_data'.
-
- A 'required_data' item can be any mapping type, and is considered ready
- if `bool(item)` evaluates as True.
- """
- service = self.get_service(service_name)
- reqs = service.get('required_data', [])
- return all(bool(req) for req in reqs)
-
- def _load_ready_file(self):
- if self._ready is not None:
- return
- if os.path.exists(self._ready_file):
- with open(self._ready_file) as fp:
- self._ready = set(json.load(fp))
- else:
- self._ready = set()
-
- def _save_ready_file(self):
- if self._ready is None:
- return
- with open(self._ready_file, 'w') as fp:
- json.dump(list(self._ready), fp)
-
- def save_ready(self, service_name):
- """
- Save an indicator that the given service is now data_ready.
- """
- self._load_ready_file()
- self._ready.add(service_name)
- self._save_ready_file()
-
- def save_lost(self, service_name):
- """
- Save an indicator that the given service is no longer data_ready.
- """
- self._load_ready_file()
- self._ready.discard(service_name)
- self._save_ready_file()
-
- def was_ready(self, service_name):
- """
- Determine if the given service was previously data_ready.
- """
- self._load_ready_file()
- return service_name in self._ready
-
-
-class ManagerCallback(object):
- """
- Special case of a callback that takes the `ServiceManager` instance
- in addition to the service name.
-
- Subclasses should implement `__call__` which should accept three parameters:
-
- * `manager` The `ServiceManager` instance
- * `service_name` The name of the service it's being triggered for
- * `event_name` The name of the event that this callback is handling
- """
- def __call__(self, manager, service_name, event_name):
- raise NotImplementedError()
-
-
-class PortManagerCallback(ManagerCallback):
- """
- Callback class that will open or close ports, for use as either
- a start or stop action.
- """
- def __call__(self, manager, service_name, event_name):
- service = manager.get_service(service_name)
- new_ports = service.get('ports', [])
- port_file = os.path.join(hookenv.charm_dir(), '.{}.ports'.format(service_name))
- if os.path.exists(port_file):
- with open(port_file) as fp:
- old_ports = fp.read().split(',')
- for old_port in old_ports:
- if bool(old_port):
- old_port = int(old_port)
- if old_port not in new_ports:
- hookenv.close_port(old_port)
- with open(port_file, 'w') as fp:
- fp.write(','.join(str(port) for port in new_ports))
- for port in new_ports:
- if event_name == 'start':
- hookenv.open_port(port)
- elif event_name == 'stop':
- hookenv.close_port(port)
-
-
-def service_stop(service_name):
- """
- Wrapper around host.service_stop to prevent spurious "unknown service"
- messages in the logs.
- """
- if host.service_running(service_name):
- host.service_stop(service_name)
-
-
-def service_restart(service_name):
- """
- Wrapper around host.service_restart to prevent spurious "unknown service"
- messages in the logs.
- """
- if host.service_available(service_name):
- if host.service_running(service_name):
- host.service_restart(service_name)
- else:
- host.service_start(service_name)
-
-
-# Convenience aliases
-open_ports = close_ports = manage_ports = PortManagerCallback()