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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/>.
#
# Copyright 2012 Canonical Ltd.
#
# Authors:
# James Page <james.page@ubuntu.com>
# Adam Gandelman <adamg@ubuntu.com>
#
"""
Helpers for clustering and determining "cluster leadership" and other
clustering-related helpers.
"""
import subprocess
import os
from socket import gethostname as get_unit_hostname
import six
from charmhelpers.core.hookenv import (
log,
relation_ids,
related_units as relation_list,
relation_get,
config as config_get,
INFO,
ERROR,
WARNING,
unit_get,
is_leader as juju_is_leader
)
from charmhelpers.core.decorators import (
retry_on_exception,
)
from charmhelpers.core.strutils import (
bool_from_string,
)
DC_RESOURCE_NAME = 'DC'
class HAIncompleteConfig(Exception):
pass
class CRMResourceNotFound(Exception):
pass
class CRMDCNotFound(Exception):
pass
def is_elected_leader(resource):
"""
Returns True if the charm executing this is the elected cluster leader.
It relies on two mechanisms to determine leadership:
1. If juju is sufficiently new and leadership election is supported,
the is_leader command will be used.
2. If the charm is part of a corosync cluster, call corosync to
determine leadership.
3. If the charm is not part of a corosync cluster, the leader is
determined as being "the alive unit with the lowest unit numer". In
other words, the oldest surviving unit.
"""
try:
return juju_is_leader()
except NotImplementedError:
log('Juju leadership election feature not enabled'
', using fallback support',
level=WARNING)
if is_clustered():
if not is_crm_leader(resource):
log('Deferring action to CRM leader.', level=INFO)
return False
else:
peers = peer_units()
if peers and not oldest_peer(peers):
log('Deferring action to oldest service unit.', level=INFO)
return False
return True
def is_clustered():
for r_id in (relation_ids('ha') or []):
for unit in (relation_list(r_id) or []):
clustered = relation_get('clustered',
rid=r_id,
unit=unit)
if clustered:
return True
return False
def is_crm_dc():
"""
Determine leadership by querying the pacemaker Designated Controller
"""
cmd = ['crm', 'status']
try:
status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
if not isinstance(status, six.text_type):
status = six.text_type(status, "utf-8")
except subprocess.CalledProcessError as ex:
raise CRMDCNotFound(str(ex))
current_dc = ''
for line in status.split('\n'):
if line.startswith('Current DC'):
# Current DC: juju-lytrusty-machine-2 (168108163) - partition with quorum
current_dc = line.split(':')[1].split()[0]
if current_dc == get_unit_hostname():
return True
elif current_dc == 'NONE':
raise CRMDCNotFound('Current DC: NONE')
return False
@retry_on_exception(5, base_delay=2,
exc_type=(CRMResourceNotFound, CRMDCNotFound))
def is_crm_leader(resource, retry=False):
"""
Returns True if the charm calling this is the elected corosync leader,
as returned by calling the external "crm" command.
We allow this operation to be retried to avoid the possibility of getting a
false negative. See LP #1396246 for more info.
"""
if resource == DC_RESOURCE_NAME:
return is_crm_dc()
cmd = ['crm', 'resource', 'show', resource]
try:
status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
if not isinstance(status, six.text_type):
status = six.text_type(status, "utf-8")
except subprocess.CalledProcessError:
status = None
if status and get_unit_hostname() in status:
return True
if status and "resource %s is NOT running" % (resource) in status:
raise CRMResourceNotFound("CRM resource %s not found" % (resource))
return False
def is_leader(resource):
log("is_leader is deprecated. Please consider using is_crm_leader "
"instead.", level=WARNING)
return is_crm_leader(resource)
def peer_units(peer_relation="cluster"):
peers = []
for r_id in (relation_ids(peer_relation) or []):
for unit in (relation_list(r_id) or []):
peers.append(unit)
return peers
def peer_ips(peer_relation='cluster', addr_key='private-address'):
'''Return a dict of peers and their private-address'''
peers = {}
for r_id in relation_ids(peer_relation):
for unit in relation_list(r_id):
peers[unit] = relation_get(addr_key, rid=r_id, unit=unit)
return peers
def oldest_peer(peers):
"""Determines who the oldest peer is by comparing unit numbers."""
local_unit_no = int(os.getenv('JUJU_UNIT_NAME').split('/')[1])
for peer in peers:
remote_unit_no = int(peer.split('/')[1])
if remote_unit_no < local_unit_no:
return False
return True
def eligible_leader(resource):
log("eligible_leader is deprecated. Please consider using "
"is_elected_leader instead.", level=WARNING)
return is_elected_leader(resource)
def https():
'''
Determines whether enough data has been provided in configuration
or relation data to configure HTTPS
.
returns: boolean
'''
use_https = config_get('use-https')
if use_https and bool_from_string(use_https):
return True
if config_get('ssl_cert') and config_get('ssl_key'):
return True
for r_id in relation_ids('identity-service'):
for unit in relation_list(r_id):
# TODO - needs fixing for new helper as ssl_cert/key suffixes with CN
rel_state = [
relation_get('https_keystone', rid=r_id, unit=unit),
relation_get('ca_cert', rid=r_id, unit=unit),
]
# NOTE: works around (LP: #1203241)
if (None not in rel_state) and ('' not in rel_state):
return True
return False
def determine_api_port(public_port, singlenode_mode=False):
'''
Determine correct API server listening port based on
existence of HTTPS reverse proxy and/or haproxy.
public_port: int: standard public port for given service
singlenode_mode: boolean: Shuffle ports when only a single unit is present
returns: int: the correct listening port for the API service
'''
i = 0
if singlenode_mode:
i += 1
elif len(peer_units()) > 0 or is_clustered():
i += 1
if https():
i += 1
return public_port - (i * 10)
def determine_apache_port(public_port, singlenode_mode=False):
'''
Description: Determine correct apache listening port based on public IP +
state of the cluster.
public_port: int: standard public port for given service
singlenode_mode: boolean: Shuffle ports when only a single unit is present
returns: int: the correct listening port for the HAProxy service
'''
i = 0
if singlenode_mode:
i += 1
elif len(peer_units()) > 0 or is_clustered():
i += 1
return public_port - (i * 10)
def get_hacluster_config(exclude_keys=None):
'''
Obtains all relevant configuration from charm configuration required
for initiating a relation to hacluster:
ha-bindiface, ha-mcastport, vip
param: exclude_keys: list of setting key(s) to be excluded.
returns: dict: A dict containing settings keyed by setting name.
raises: HAIncompleteConfig if settings are missing.
'''
settings = ['ha-bindiface', 'ha-mcastport', 'vip']
conf = {}
for setting in settings:
if exclude_keys and setting in exclude_keys:
continue
conf[setting] = config_get(setting)
missing = []
[missing.append(s) for s, v in six.iteritems(conf) if v is None]
if missing:
log('Insufficient config data to configure hacluster.', level=ERROR)
raise HAIncompleteConfig
return conf
def canonical_url(configs, vip_setting='vip'):
'''
Returns the correct HTTP URL to this host given the state of HTTPS
configuration and hacluster.
:configs : OSTemplateRenderer: A config tempating object to inspect for
a complete https context.
:vip_setting: str: Setting in charm config that specifies
VIP address.
'''
scheme = 'http'
if 'https' in configs.complete_contexts():
scheme = 'https'
if is_clustered():
addr = config_get(vip_setting)
else:
addr = unit_get('private-address')
return '%s://%s' % (scheme, addr)
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