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# Copyright 2015-2016 Canonical Ltd.
#
# This file is part of the Leadership Layer for Juju.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranties of
# MERCHANTABILITY, SATISFACTORY QUALITY, 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 this program. If not, see <http://www.gnu.org/licenses/>.
from charmhelpers.core import hookenv
from charmhelpers.core import unitdata
from charms import reactive
from charms.leadership import leader_get, leader_set
__all__ = ['leader_get', 'leader_set'] # Backwards compatibility
def initialize_leadership_state():
'''Initialize leadership.* states from the hook environment.
Invoked by hookenv.atstart() so states are available in
@hook decorated handlers.
'''
is_leader = hookenv.is_leader()
if is_leader:
hookenv.log('Initializing Leadership Layer (is leader)')
else:
hookenv.log('Initializing Leadership Layer (is follower)')
reactive.helpers.toggle_state('leadership.is_leader', is_leader)
previous = unitdata.kv().getrange('leadership.settings.', strip=True)
current = hookenv.leader_get()
# Handle deletions.
for key in set(previous.keys()) - set(current.keys()):
current[key] = None
any_changed = False
for key, value in current.items():
reactive.helpers.toggle_state('leadership.changed.{}'.format(key),
value != previous.get(key))
if value != previous.get(key):
any_changed = True
reactive.helpers.toggle_state('leadership.set.{}'.format(key),
value is not None)
reactive.helpers.toggle_state('leadership.changed', any_changed)
unitdata.kv().update(current, prefix='leadership.settings.')
# Per https://github.com/juju-solutions/charms.reactive/issues/33,
# this module may be imported multiple times so ensure the
# initialization hook is only registered once. I have to piggy back
# onto the namespace of a module imported before reactive discovery
# to do this.
if not hasattr(reactive, '_leadership_registered'):
hookenv.atstart(initialize_leadership_state)
reactive._leadership_registered = True
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