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Diffstat (limited to 'charms/trusty/ceilometer/charmhelpers/contrib/hahelpers/cluster.py')
| -rw-r--r-- | charms/trusty/ceilometer/charmhelpers/contrib/hahelpers/cluster.py | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/charms/trusty/ceilometer/charmhelpers/contrib/hahelpers/cluster.py b/charms/trusty/ceilometer/charmhelpers/contrib/hahelpers/cluster.py new file mode 100644 index 0000000..aa0b515 --- /dev/null +++ b/charms/trusty/ceilometer/charmhelpers/contrib/hahelpers/cluster.py @@ -0,0 +1,316 @@ +# 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) |