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# Copyright 2014-2015 Canonical Limited.
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# This file is part of charm-helpers.
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# charm-helpers is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License version 3 as
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# published by the Free Software Foundation.
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# charm-helpers is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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# You should have received a copy of the GNU Lesser General Public License
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# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
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# Copyright 2012 Canonical Ltd.
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# James Page <james.page@ubuntu.com>
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# Adam Gandelman <adamg@ubuntu.com>
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Helpers for clustering and determining "cluster leadership" and other
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clustering-related helpers.
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from socket import gethostname as get_unit_hostname
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from charmhelpers.core.hookenv import (
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related_units as relation_list,
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from charmhelpers.core.decorators import (
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from charmhelpers.core.strutils import (
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DC_RESOURCE_NAME = 'DC'
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class HAIncompleteConfig(Exception):
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class CRMResourceNotFound(Exception):
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def is_elected_leader(resource):
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Returns True if the charm executing this is the elected cluster leader.
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It relies on two mechanisms to determine leadership:
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1. If the charm is part of a corosync cluster, call corosync to
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2. If the charm is not part of a corosync cluster, the leader is
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determined as being "the alive unit with the lowest unit numer". In
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other words, the oldest surviving unit.
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if not is_crm_leader(resource):
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log('Deferring action to CRM leader.', level=INFO)
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if peers and not oldest_peer(peers):
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log('Deferring action to oldest service unit.', level=INFO)
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for r_id in (relation_ids('ha') or []):
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for unit in (relation_list(r_id) or []):
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clustered = relation_get('clustered',
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Determine leadership by querying the pacemaker Designated Controller
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cmd = ['crm', 'status']
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status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
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if not isinstance(status, six.text_type):
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status = six.text_type(status, "utf-8")
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except subprocess.CalledProcessError:
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for line in status.split('\n'):
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if line.startswith('Current DC'):
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# Current DC: juju-lytrusty-machine-2 (168108163) - partition with quorum
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current_dc = line.split(':')[1].split()[0]
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if current_dc == get_unit_hostname():
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@retry_on_exception(5, base_delay=2, exc_type=CRMResourceNotFound)
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def is_crm_leader(resource, retry=False):
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Returns True if the charm calling this is the elected corosync leader,
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as returned by calling the external "crm" command.
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We allow this operation to be retried to avoid the possibility of getting a
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false negative. See LP #1396246 for more info.
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if resource == DC_RESOURCE_NAME:
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cmd = ['crm', 'resource', 'show', resource]
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status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
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if not isinstance(status, six.text_type):
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status = six.text_type(status, "utf-8")
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except subprocess.CalledProcessError:
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if status and get_unit_hostname() in status:
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if status and "resource %s is NOT running" % (resource) in status:
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raise CRMResourceNotFound("CRM resource %s not found" % (resource))
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def is_leader(resource):
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log("is_leader is deprecated. Please consider using is_crm_leader "
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"instead.", level=WARNING)
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return is_crm_leader(resource)
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def peer_units(peer_relation="cluster"):
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for r_id in (relation_ids(peer_relation) or []):
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for unit in (relation_list(r_id) or []):
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def peer_ips(peer_relation='cluster', addr_key='private-address'):
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'''Return a dict of peers and their private-address'''
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for r_id in relation_ids(peer_relation):
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for unit in relation_list(r_id):
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peers[unit] = relation_get(addr_key, rid=r_id, unit=unit)
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def oldest_peer(peers):
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"""Determines who the oldest peer is by comparing unit numbers."""
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local_unit_no = int(os.getenv('JUJU_UNIT_NAME').split('/')[1])
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remote_unit_no = int(peer.split('/')[1])
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if remote_unit_no < local_unit_no:
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def eligible_leader(resource):
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log("eligible_leader is deprecated. Please consider using "
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"is_elected_leader instead.", level=WARNING)
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return is_elected_leader(resource)
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Determines whether enough data has been provided in configuration
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or relation data to configure HTTPS
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use_https = config_get('use-https')
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if use_https and bool_from_string(use_https):
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if config_get('ssl_cert') and config_get('ssl_key'):
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for r_id in relation_ids('identity-service'):
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for unit in relation_list(r_id):
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# TODO - needs fixing for new helper as ssl_cert/key suffixes with CN
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relation_get('https_keystone', rid=r_id, unit=unit),
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relation_get('ca_cert', rid=r_id, unit=unit),
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# NOTE: works around (LP: #1203241)
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if (None not in rel_state) and ('' not in rel_state):
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def determine_api_port(public_port, singlenode_mode=False):
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Determine correct API server listening port based on
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existence of HTTPS reverse proxy and/or haproxy.
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public_port: int: standard public port for given service
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singlenode_mode: boolean: Shuffle ports when only a single unit is present
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returns: int: the correct listening port for the API service
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elif len(peer_units()) > 0 or is_clustered():
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return public_port - (i * 10)
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def determine_apache_port(public_port, singlenode_mode=False):
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Description: Determine correct apache listening port based on public IP +
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state of the cluster.
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public_port: int: standard public port for given service
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singlenode_mode: boolean: Shuffle ports when only a single unit is present
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returns: int: the correct listening port for the HAProxy service
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elif len(peer_units()) > 0 or is_clustered():
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return public_port - (i * 10)
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def get_hacluster_config(exclude_keys=None):
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Obtains all relevant configuration from charm configuration required
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for initiating a relation to hacluster:
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ha-bindiface, ha-mcastport, vip
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param: exclude_keys: list of setting key(s) to be excluded.
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returns: dict: A dict containing settings keyed by setting name.
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raises: HAIncompleteConfig if settings are missing.
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settings = ['ha-bindiface', 'ha-mcastport', 'vip']
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for setting in settings:
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if exclude_keys and setting in exclude_keys:
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conf[setting] = config_get(setting)
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[missing.append(s) for s, v in six.iteritems(conf) if v is None]
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log('Insufficient config data to configure hacluster.', level=ERROR)
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raise HAIncompleteConfig
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def canonical_url(configs, vip_setting='vip'):
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Returns the correct HTTP URL to this host given the state of HTTPS
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configuration and hacluster.
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:configs : OSTemplateRenderer: A config tempating object to inspect for
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a complete https context.
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:vip_setting: str: Setting in charm config that specifies
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if 'https' in configs.complete_contexts():
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addr = config_get(vip_setting)
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addr = unit_get('private-address')
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return '%s://%s' % (scheme, addr)
added
removed
hooks/charmhelpers/contrib/hahelpers/cluster.py
