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# Copyright 2014-2016 Canonical Limited.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Copyright 2016 Canonical Ltd.
#
# Authors:
# Openstack Charmers <
#
"""
Helpers for high availability.
"""
import re
from charmhelpers.core.hookenv import (
log,
relation_set,
charm_name,
config,
status_set,
DEBUG,
)
from charmhelpers.core.host import (
lsb_release
)
from charmhelpers.contrib.openstack.ip import (
resolve_address,
)
class DNSHAException(Exception):
"""Raised when an error occurs setting up DNS HA
"""
pass
def update_dns_ha_resource_params(resources, resource_params,
relation_id=None,
crm_ocf='ocf:maas:dns'):
""" Check for os-*-hostname settings and update resource dictionaries for
the HA relation.
@param resources: Pointer to dictionary of resources.
Usually instantiated in ha_joined().
@param resource_params: Pointer to dictionary of resource parameters.
Usually instantiated in ha_joined()
@param relation_id: Relation ID of the ha relation
@param crm_ocf: Corosync Open Cluster Framework resource agent to use for
DNS HA
"""
# Validate the charm environment for DNS HA
assert_charm_supports_dns_ha()
settings = ['os-admin-hostname', 'os-internal-hostname',
'os-public-hostname', 'os-access-hostname']
# Check which DNS settings are set and update dictionaries
hostname_group = []
for setting in settings:
hostname = config(setting)
if hostname is None:
log('DNS HA: Hostname setting {} is None. Ignoring.'
''.format(setting),
DEBUG)
continue
m = re.search('os-(.+?)-hostname', setting)
if m:
networkspace = m.group(1)
else:
msg = ('Unexpected DNS hostname setting: {}. '
'Cannot determine network space name'
''.format(setting))
status_set('blocked', msg)
raise DNSHAException(msg)
hostname_key = 'res_{}_{}_hostname'.format(charm_name(), networkspace)
if hostname_key in hostname_group:
log('DNS HA: Resource {}: {} already exists in '
'hostname group - skipping'.format(hostname_key, hostname),
DEBUG)
continue
hostname_group.append(hostname_key)
resources[hostname_key] = crm_ocf
resource_params[hostname_key] = (
'params fqdn="{}" ip_address="{}" '
''.format(hostname, resolve_address(endpoint_type=networkspace,
override=False)))
if len(hostname_group) >= 1:
log('DNS HA: Hostname group is set with {} as members. '
'Informing the ha relation'.format(' '.join(hostname_group)),
DEBUG)
relation_set(relation_id=relation_id, groups={
'grp_{}_hostnames'.format(charm_name()): ' '.join(hostname_group)})
else:
msg = 'DNS HA: Hostname group has no members.'
status_set('blocked', msg)
raise DNSHAException(msg)
def assert_charm_supports_dns_ha():
"""Validate prerequisites for DNS HA
The MAAS client is only available on Xenial or greater
"""
if lsb_release().get('DISTRIB_RELEASE') < '16.04':
msg = ('DNS HA is only supported on 16.04 and greater '
'versions of Ubuntu.')
status_set('blocked', msg)
raise DNSHAException(msg)
return True
def expect_ha():
""" Determine if the unit expects to be in HA
Check for VIP or dns-ha settings which indicate the unit should expect to
be related to hacluster.
@returns boolean
"""
return config('vip') or config('dns-ha')
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