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# Copyright 2020 Catalyst Cloud
#
# 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.
import os
from oslo_log import log as logging
from oslo_utils import netutils
from trove.common import cfg
from trove.common import exception
from trove.common import utils
from trove.common.db.postgresql import models
from trove.guestagent.common import operating_system
from trove.guestagent.common.operating_system import FileMode
from trove.guestagent.datastore.postgres import service as pg_service
from trove.guestagent.strategies.replication import base
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
REPL_USER = 'replicator'
class PostgresqlReplicationStreaming(base.Replication):
def _create_replication_user(self, service, adm_mgr, pwfile):
"""Create the replication user and password file.
Unfortunately, to be able to run pg_rewind, we need SUPERUSER, not just
REPLICATION privilege
"""
pw = utils.generate_random_password()
operating_system.write_file(pwfile, pw, as_root=True)
operating_system.chown(pwfile, user=CONF.database_service_uid,
group=CONF.database_service_uid, as_root=True)
operating_system.chmod(pwfile, FileMode.SET_USR_RWX(),
as_root=True)
LOG.debug(f"File {pwfile} created")
LOG.debug(f"Creating replication user {REPL_USER}")
repl_user = models.PostgreSQLUser(name=REPL_USER, password=pw)
adm_mgr.create_user(repl_user, None,
*('REPLICATION', 'SUPERUSER', 'LOGIN'))
return pw
def _get_or_create_replication_user(self, service):
"""There are three scenarios we need to deal with here:
- This is a fresh master, with no replicator user created.
Generate a new u/p
- We are attaching a new slave and need to give it the login creds
Send the creds we have stored in PGDATA/.replpass
- This is a failed-over-to slave, who will have the replicator user
but not the credentials file. Recreate the repl user in this case
"""
LOG.debug("Checking for replication user")
pwfile = os.path.join(service.datadir, ".replpass")
adm_mgr = service.adm
if adm_mgr.user_exists(REPL_USER):
if operating_system.exists(pwfile, as_root=True):
LOG.debug("Found existing .replpass")
pw = operating_system.read_file(pwfile, as_root=True)
else:
LOG.debug("Found user but not .replpass, recreate")
adm_mgr.delete_user(models.PostgreSQLUser(REPL_USER))
pw = self._create_replication_user(service, adm_mgr, pwfile)
else:
LOG.debug("Found no replicator user, create one")
pw = self._create_replication_user(service, adm_mgr, pwfile)
repl_user_info = {
'name': REPL_USER,
'password': pw
}
return repl_user_info
def enable_as_master(self, service, master_config):
"""Primary postgredql settings.
For a server to be a master in postgres, we need to enable
the replication user in pg_hba.conf
"""
self._get_or_create_replication_user(service)
hba_entry = f"host replication {REPL_USER} 0.0.0.0/0 md5\n"
tmp_hba = '/tmp/pg_hba'
operating_system.copy(pg_service.HBA_CONFIG_FILE, tmp_hba,
force=True, as_root=True)
operating_system.chmod(tmp_hba, FileMode.SET_ALL_RWX(),
as_root=True)
with open(tmp_hba, 'a+') as hba_file:
hba_file.write(hba_entry)
operating_system.copy(tmp_hba, pg_service.HBA_CONFIG_FILE,
force=True, as_root=True)
operating_system.chown(pg_service.HBA_CONFIG_FILE,
user=CONF.database_service_uid,
group=CONF.database_service_uid, as_root=True)
operating_system.chmod(pg_service.HBA_CONFIG_FILE,
FileMode.SET_USR_RWX(),
as_root=True)
operating_system.remove(tmp_hba, as_root=True)
LOG.debug(f"{pg_service.HBA_CONFIG_FILE} changed")
service.restart()
def snapshot_for_replication(self, context, service, adm, location,
snapshot_info):
LOG.info("Creating backup for replication")
volumes_mapping = {
'/var/lib/postgresql/data': {
'bind': '/var/lib/postgresql/data', 'mode': 'rw'
},
"/var/run/postgresql": {"bind": "/var/run/postgresql",
"mode": "ro"},
}
extra_params = f"--pg-wal-archive-dir {pg_service.WAL_ARCHIVE_DIR}"
service.create_backup(context, snapshot_info,
volumes_mapping=volumes_mapping,
need_dbuser=False,
extra_params=extra_params)
LOG.info('Getting or creating replication user')
replication_user = self._get_or_create_replication_user(service)
replica_conf = {
'log_position': {},
'replication_user': replication_user
}
return snapshot_info['id'], replica_conf
def get_master_ref(self, service, snapshot_info):
master_ref = {
'host': netutils.get_my_ipv4(),
'port': cfg.get_configuration_property('postgresql_port')
}
return master_ref
def enable_as_slave(self, service, snapshot, slave_config):
"""Set up the replica server."""
signal_file = f"{service.datadir}/standby.signal"
operating_system.execute_shell_cmd(
f"touch {signal_file}", [], shell=True, as_root=True)
operating_system.chown(signal_file, CONF.database_service_uid,
CONF.database_service_uid, force=True,
as_root=True)
LOG.debug("Standby signal file created")
user = snapshot['replica_conf']['replication_user']
conninfo = (f"host={snapshot['master']['host']} "
f"port={snapshot['master']['port']} "
f"dbname=postgres "
f"user={user['name']} password={user['password']}")
service.configuration_manager.apply_system_override(
{'primary_conninfo': conninfo})
LOG.debug("primary_conninfo is set in the config file.")
def detach_slave(self, service, for_failover):
"""Promote replica and wait for its running.
Running on replica, detach from the primary.
"""
service.adm.query("select pg_promote()")
def _wait_for_failover():
"""Wait until slave has switched out of recovery mode"""
return not service.is_replica()
try:
utils.poll_until(_wait_for_failover, time_out=60)
except exception.PollTimeOut:
raise exception.TroveError(
"Timeout occurred waiting for replica to exit standby mode")
def get_replica_context(self, service, adm):
"""Running on primary."""
repl_user_info = self._get_or_create_replication_user(service)
return {
'log_position': {},
'master': self.get_master_ref(None, None),
'replica_conf': {'replication_user': repl_user_info}
}
def cleanup_source_on_replica_detach(self, admin_service, replica_info):
pass
def _pg_rewind(self, service):
conn_info = service.configuration_manager.get_value('primary_conninfo')
service.pg_rewind(conn_info)
signal_file = f"{service.datadir}/standby.signal"
operating_system.execute_shell_cmd(
f"touch {signal_file}", [], shell=True, as_root=True)
operating_system.chown(signal_file, CONF.database_service_uid,
CONF.database_service_uid, force=True,
as_root=True)
LOG.debug("Standby signal file created")
def demote_master(self, service):
"""Running on the old primary.
In order to demote a master we need to shutdown the server and call
pg_rewind against the new master to enable a proper timeline
switch.
"""
service.stop_db()
self._pg_rewind(service)
service.restart()
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