/
postgresql.py
782 lines (685 loc) · 32.9 KB
/
postgresql.py
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import logging
import os
import psycopg2
import shlex
import shutil
import subprocess
import tempfile
import time
from patroni.exceptions import PostgresConnectionException, PostgresException
from patroni.utils import Retry, RetryFailedError
from six import string_types
from six.moves.urllib_parse import urlparse
from threading import Lock
logger = logging.getLogger(__name__)
ACTION_ON_START = "on_start"
ACTION_ON_STOP = "on_stop"
ACTION_ON_RESTART = "on_restart"
ACTION_ON_RELOAD = "on_reload"
ACTION_ON_ROLE_CHANGE = "on_role_change"
def parseurl(url):
r = urlparse(url)
ret = {
'host': r.hostname,
'port': r.port or 5432,
'database': r.path[1:],
'fallback_application_name': 'Patroni',
'connect_timeout': 3,
'options': '-c statement_timeout=2000',
}
if r.username:
ret['user'] = r.username
if r.password:
ret['password'] = r.password
return ret
class Postgresql(object):
def __init__(self, config):
self.config = config
self.name = config['name']
self.server_parameters = config.get('parameters', {})
self.scope = config['scope']
self.listen_addresses, self.port = config['listen'].split(':')
self.data_dir = config['data_dir']
self.replication = config['replication']
self.superuser = config['superuser']
self.admin = config['admin']
self.initdb_options = config.get('initdb', [])
self.pgpass = config.get('pgpass') or os.path.join(os.path.expanduser('~'), 'pgpass')
self.pg_rewind = config.get('pg_rewind', {})
self.callback = config.get('callbacks', {})
self.use_slots = config.get('use_slots', True)
self.schedule_load_slots = self.use_slots
self.recovery_conf = os.path.join(self.data_dir, 'recovery.conf')
self.configuration_to_save = (os.path.join(self.data_dir, 'pg_hba.conf'),
os.path.join(self.data_dir, 'postgresql.conf'))
self.postmaster_pid = os.path.join(self.data_dir, 'postmaster.pid')
self.trigger_file = config.get('recovery_conf', {}).get('trigger_file') or 'promote'
self.trigger_file = os.path.abspath(os.path.join(self.data_dir, self.trigger_file))
self._pg_ctl = ['pg_ctl', '-w', '-D', self.data_dir]
self.local_address = self.get_local_address()
connect_address = config.get('connect_address') or self.local_address
self.connection_string = 'postgres://{username}:{password}@{connect_address}/postgres'.format(
connect_address=connect_address, **self.replication)
self._connection = None
self._cursor_holder = None
self._sysid = None
self.replication_slots = [] # list of already existing replication slots
self.retry = Retry(max_tries=-1, deadline=5, max_delay=1, retry_exceptions=PostgresConnectionException)
self._state = 'stopped'
self._state_lock = Lock()
self._role = self.get_postgres_role_from_data_directory()
self._role_lock = Lock()
if self.is_running():
self._state = 'running'
self._role = 'master' if self.is_leader() else 'replica'
@property
def can_rewind(self):
""" check if pg_rewind executable is there and that pg_controldata indicates
we have either wal_log_hints or checksums turned on
"""
# low-hanging fruit: check if pg_rewind configuration is there
if not self.pg_rewind or\
not (self.pg_rewind.get('username', '') and self.pg_rewind.get('password', '')):
return False
cmd = ['pg_rewind', '--help']
try:
ret = subprocess.call(cmd, stdout=open(os.devnull, 'w'), stderr=subprocess.STDOUT)
if ret != 0: # pg_rewind is not there, close up the shop and go home
return False
except OSError:
return False
# check if the cluster's configuration permits pg_rewind
data = self.controldata()
return data.get('wal_log_hints setting', 'off') == 'on' or data.get('Data page checksum version', '0') != '0'
@property
def sysid(self):
if not self._sysid:
data = self.controldata()
self._sysid = data.get('Database system identifier', "")
return self._sysid
def get_local_address(self):
listen_addresses = self.listen_addresses.split(',')
local_address = listen_addresses[0].strip() # take first address from listen_addresses
for la in listen_addresses:
if la.strip() in ['*', '0.0.0.0']: # we are listening on *
local_address = 'localhost' # connection via localhost is preferred
break
return local_address + ':' + self.port
def get_postgres_role_from_data_directory(self):
return 'replica' if os.path.exists(self.recovery_conf) else 'master'
@property
def _connect_kwargs(self):
r = parseurl('postgres://{0}/postgres'.format(self.local_address))
if 'username' in self.superuser:
r['user'] = self.superuser['username']
if 'password' in self.superuser:
r['password'] = self.superuser['password']
return r
def connection(self):
if not self._connection or self._connection.closed != 0:
self._connection = psycopg2.connect(**self._connect_kwargs)
self._connection.autocommit = True
self.server_version = self._connection.server_version
return self._connection
def _cursor(self):
if not self._cursor_holder or self._cursor_holder.closed or self._cursor_holder.connection.closed != 0:
logger.info("establishing a new patroni connection to the postgres cluster")
self._cursor_holder = self.connection().cursor()
return self._cursor_holder
def close_connection(self):
if self._cursor_holder and self._cursor_holder.connection and self._cursor_holder.connection.closed == 0:
self._cursor_holder.connection.close()
logger.info("closed patroni connection to the postgresql cluster")
def _query(self, sql, *params):
cursor = None
try:
cursor = self._cursor()
cursor.execute(sql, params)
return cursor
except psycopg2.Error as e:
if cursor and cursor.connection.closed == 0:
raise e
if self.state == 'restarting':
raise RetryFailedError('cluster is being restarted')
raise PostgresConnectionException('connection problems')
def query(self, sql, *params):
try:
return self.retry(self._query, sql, *params)
except RetryFailedError as e:
raise PostgresConnectionException(str(e))
def data_directory_empty(self):
return not os.path.exists(self.data_dir) or os.listdir(self.data_dir) == []
@staticmethod
def initdb_allowed_option(name):
if name in ['pgdata', 'nosync', 'pwfile', 'sync-only']:
raise Exception('{0} option for initdb is not allowed'.format(name))
return True
def get_initdb_options(self):
options = []
for o in self.initdb_options:
if isinstance(o, string_types) and self.initdb_allowed_option(o):
options.append('--{0}'.format(o))
elif isinstance(o, dict):
keys = list(o.keys())
if len(keys) != 1 or not isinstance(keys[0], string_types) or not self.initdb_allowed_option(keys[0]):
raise Exception('Invalid option: {0}'.format(o))
options.append('--{0}={1}'.format(keys[0], o[keys[0]]))
else:
raise Exception('Unknown type of initdb option: {0}'.format(o))
return options
def initialize(self):
self.set_state('initalizing new cluster')
options = self.get_initdb_options()
pwfile = None
if self.superuser:
if 'username' in self.superuser:
options.append('--username={0}'.format(self.superuser['username']))
if 'password' in self.superuser:
(fd, pwfile) = tempfile.mkstemp()
os.write(fd, self.superuser['password'].encode('utf-8'))
os.close(fd)
options.append('--pwfile={0}'.format(pwfile))
ret = subprocess.call(self._pg_ctl + ['initdb'] + (['-o', ' '.join(options)] if options else [])) == 0
if pwfile:
os.remove(pwfile)
if ret:
self.write_pg_hba()
else:
self.set_state('initdb failed')
return ret
def delete_trigger_file(self):
if os.path.exists(self.trigger_file):
os.unlink(self.trigger_file)
def write_pgpass(self, record):
with open(self.pgpass, 'w') as f:
os.fchmod(f.fileno(), 0o600)
f.write('{host}:{port}:*:{user}:{password}\n'.format(**record))
env = os.environ.copy()
env['PGPASSFILE'] = self.pgpass
return env
def sync_replica(self, clone_member):
# add the credentials to connect to the replica origin to pgpass.
env = self.write_pgpass(parseurl(clone_member.conn_url)) if clone_member else os.environ.copy()
if self.create_replica(clone_member, env) == 0:
self.delete_trigger_file()
return True
return False
@staticmethod
def build_connstring(conn):
"""
>>> Postgresql.build_connstring({'host': '127.0.0.1', 'port': '5432'}) == 'host=127.0.0.1 port=5432'
True
"""
return ' '.join('{0}={1}'.format(param, val) for param, val in sorted(conn.items()))
def replica_method_can_work_without_replication_connection(self, method):
return method != 'basebackup' and self.config and self.config.get(method, {}).get('no_master')
def can_create_replica_without_replication_connection(self):
""" go through the replication methods to see if there are ones
that does not require a working replication connection.
"""
replica_methods = self.config.get('create_replica_method', [])
return any(self.replica_method_can_work_without_replication_connection(replica_method)
for replica_method in replica_methods)
def create_replica(self, clone_member, env):
# create the replica according to the replica_method
# defined by the user. this is a list, so we need to
# loop through all methods the user supplies
connstring = clone_member.conn_url if clone_member else ""
# get list of replica methods from config.
# If there is no configuration key, or no value is specified, use basebackup
replica_methods = self.config.get('create_replica_method') or ['basebackup']
# if we don't have any source, leave only replica methods that work without it
replica_methods = replica_methods if clone_member else \
[r for r in replica_methods if self.replica_method_can_work_without_replication_connection(r)]
# go through them in priority order
ret = 1
for replica_method in replica_methods:
# if the method is basebackup, then use the built-in
if replica_method == "basebackup":
ret = self.basebackup(clone_member, env)
if ret == 0:
logger.info("replica has been created using basebackup")
# if basebackup succeeds, exit with success
break
else:
cmd = replica_method
method_config = {}
# user-defined method; check for configuration
# not required, actually
if replica_method in self.config:
method_config = self.config[replica_method].copy()
# look to see if the user has supplied a full command path
# if not, use the method name as the command
cmd = method_config.pop('command', cmd)
# add the default parameters
try:
method_config.update({"scope": self.scope,
"role": "replica",
"datadir": self.data_dir,
"connstring": connstring})
params = ["--{0}={1}".format(arg, val) for arg, val in method_config.items()]
# call script with the full set of parameters
ret = subprocess.call(shlex.split(cmd) + params, env=env)
# if we succeeded, stop
if ret == 0:
logger.info("replica has been created using {0}".format(replica_method))
break
except Exception as e:
logger.exception('Error creating replica using method {0}: {1}'.format(replica_method, str(e)))
ret = 1
return ret
def is_leader(self):
return not self.query('SELECT pg_is_in_recovery()').fetchone()[0]
def is_running(self):
return subprocess.call(' '.join(self._pg_ctl) + ' status > /dev/null 2>&1', shell=True) == 0
def call_nowait(self, cb_name):
""" pick a callback command and call it without waiting for it to finish """
if not self.callback or cb_name not in self.callback:
return False
cmd = self.callback[cb_name]
try:
subprocess.Popen(shlex.split(cmd) + [cb_name, self.role, self.scope])
except OSError:
logger.exception('callback %s %s %s %s failed', cmd, cb_name, self.role, self.scope)
return False
return True
@property
def role(self):
with self._role_lock:
return self._role
def set_role(self, value):
with self._role_lock:
self._role = value
@property
def state(self):
with self._state_lock:
return self._state
def set_state(self, value):
with self._state_lock:
self._state = value
def start(self, block_callbacks=False):
if self.is_running():
logger.error('Cannot start PostgreSQL because one is already running.')
return True
self.set_role(self.get_postgres_role_from_data_directory())
if os.path.exists(self.postmaster_pid):
os.remove(self.postmaster_pid)
logger.info('Removed %s', self.postmaster_pid)
if not block_callbacks:
self.set_state('starting')
env = os.environ.copy()
if 'username' in self.superuser:
env['PGUSER'] = self.superuser['username']
ret = subprocess.call(self._pg_ctl + ['start', '-o', self.server_options()], env=env, preexec_fn=os.setsid) == 0
self.set_state('running' if ret else 'start failed')
self.schedule_load_slots = ret and self.use_slots
self.save_configuration_files()
# block_callbacks is used during restart to avoid
# running start/stop callbacks in addition to restart ones
if ret and not block_callbacks:
self.call_nowait(ACTION_ON_START)
return ret
def checkpoint(self, connect_kwargs=None):
connect_kwargs = connect_kwargs or self._connect_kwargs
for p in ['connect_timeout', 'options']:
connect_kwargs.pop(p, None)
try:
with psycopg2.connect(**connect_kwargs) as conn:
conn.autocommit = True
with conn.cursor() as cur:
cur.execute("SET statement_timeout = 0")
cur.execute('CHECKPOINT')
except psycopg2.Error:
logging.exception('Exception during CHECKPOINT')
def stop(self, mode='fast', block_callbacks=False, checkpoint=True):
# make sure we close all connections established against
# the former node, otherwise, we might get a stalled one
# after kill -9, which would report incorrect data to
# patroni.
self.close_connection()
if not self.is_running():
if not block_callbacks:
self.set_state('stopped')
return True
if checkpoint:
self.checkpoint()
if not block_callbacks:
self.set_state('stopping')
ret = subprocess.call(self._pg_ctl + ['stop', '-m', mode]) == 0
# block_callbacks is used during restart to avoid
# running start/stop callbacks in addition to restart ones
if not ret:
self.set_state('stop failed')
elif not block_callbacks:
self.set_state('stopped')
self.call_nowait(ACTION_ON_STOP)
return ret
def reload(self):
ret = subprocess.call(self._pg_ctl + ['reload']) == 0
if ret:
self.call_nowait(ACTION_ON_RELOAD)
return ret
def restart(self):
self.set_state('restarting')
ret = self.stop(block_callbacks=True) and self.start(block_callbacks=True)
if ret:
self.call_nowait(ACTION_ON_RESTART)
else:
self.set_state('restart failed ({0})'.format(self.state))
return ret
def server_options(self):
options = "--listen_addresses='{0}' --port={1}".format(self.listen_addresses, self.port)
for setting, value in self.server_parameters.items():
options += " --{0}='{1}'".format(setting, value)
return options
def is_healthy(self):
if not self.is_running():
logger.warning('Postgresql is not running.')
return False
return True
def check_replication_lag(self, last_leader_operation):
return (last_leader_operation or 0) - self.xlog_position() <= self.config.get('maximum_lag_on_failover', 0)
def write_pg_hba(self):
with open(os.path.join(self.data_dir, 'pg_hba.conf'), 'a') as f:
f.write('\nhost replication {username} {network} md5\n'.format(**self.replication))
for line in self.config.get('pg_hba', []):
if line.split()[0].strip() == 'hostssl' and self.server_parameters.get('ssl', 'off').lower() != 'on':
continue
f.write(line + '\n')
@staticmethod
def primary_conninfo(leader_url):
r = parseurl(leader_url)
return 'user={user} password={password} host={host} port={port} sslmode=prefer sslcompression=1'.format(**r)
def check_recovery_conf(self, leader):
if not os.path.isfile(self.recovery_conf):
return False
pattern = leader and leader.conn_url and self.primary_conninfo(leader.conn_url)
with open(self.recovery_conf, 'r') as f:
for line in f:
if line.startswith('primary_conninfo'):
return pattern and (pattern in line)
return not pattern
def write_recovery_conf(self, leader, bootstrap=False):
with open(self.recovery_conf, 'w') as f:
f.write("""standby_mode = 'on'
recovery_target_timeline = 'latest'
""")
if leader and leader.conn_url:
f.write("""primary_conninfo = '{0}'\n""".format(self.primary_conninfo(leader.conn_url)))
if self.use_slots:
f.write("""primary_slot_name = '{0}'\n""".format(self.name))
if (leader and leader.conn_url) or bootstrap:
for name, value in self.config.get('recovery_conf', {}).items():
f.write("{0} = '{1}'\n".format(name, value))
def rewind(self, leader):
# prepare pg_rewind connection
r = parseurl(leader.conn_url)
r.update(self.pg_rewind)
r['user'] = r.pop('username')
env = self.write_pgpass(r)
pc = "user={user} host={host} port={port} dbname=postgres sslmode=prefer sslcompression=1".format(**r)
# first run a checkpoint on a promoted master in order
# to make it store the new timeline (5540277D.8020309@iki.fi)
self.checkpoint(r)
logger.info("running pg_rewind from %s", pc)
pg_rewind = ['pg_rewind', '-D', self.data_dir, '--source-server', pc]
try:
ret = subprocess.call(pg_rewind, env=env) == 0
except OSError:
ret = False
if ret:
self.write_recovery_conf(leader)
return ret
def controldata(self):
""" return the contents of pg_controldata, or non-True value if pg_controldata call failed """
result = {}
try:
data = subprocess.check_output(['pg_controldata', self.data_dir])
if data:
data = data.decode('utf-8').splitlines()
result = {l.split(':')[0].replace('Current ', '', 1): l.split(':')[1].strip() for l in data if l}
except subprocess.CalledProcessError:
logger.exception("Error when calling pg_controldata")
return result
def read_postmaster_opts(self):
""" returns the list of option names/values from postgres.opts, Empty dict if read failed or no file """
result = {}
try:
with open(os.path.join(self.data_dir, "postmaster.opts")) as f:
data = f.read()
opts = [opt.strip('"\n') for opt in data.split(' "')]
for opt in opts:
if '=' in opt and opt.startswith('--'):
name, val = opt.split('=', 1)
name = name.strip('-')
result[name] = val
except IOError:
logger.exception('Error when reading postmaster.opts')
return result
def single_user_mode(self, command=None, options=None):
""" run a given command in a single-user mode. If the command is empty - then just start and stop """
cmd = ['postgres', '--single', '-D', self.data_dir]
for opt, val in sorted((options or {}).items()):
cmd.extend(['-c', '{0}={1}'.format(opt, val)])
# need a database name to connect
cmd.append('postgres')
p = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=open(os.devnull, 'w'), stderr=subprocess.STDOUT)
if p:
if command:
p.communicate('{0}\n'.format(command))
p.stdin.close()
return p.wait()
return 1
def cleanup_archive_status(self):
status_dir = os.path.join(self.data_dir, 'pg_xlog', 'archive_status')
try:
for f in os.listdir(status_dir):
path = os.path.join(status_dir, f)
try:
if os.path.islink(path):
os.unlink(path)
elif os.path.isfile(path):
os.remove(path)
except OSError:
logger.exception("Unable to remove %s", path)
except OSError:
logger.exception("Unable to list %s", status_dir)
def follow(self, leader, recovery=False):
if self.check_recovery_conf(leader) and not recovery:
return True
change_role = self.role == 'master'
need_rewind = change_role and self.can_rewind
if need_rewind:
logger.info("set the rewind flag after demote")
self.write_recovery_conf(leader)
if leader and need_rewind: # we have a leader and need to rewind
if self.is_running():
self.stop()
# at present, pg_rewind only runs when the cluster is shut down cleanly
# and not shutdown in recovery. We have to remove the recovery.conf if present
# and start/shutdown in a single user mode to emulate this.
# XXX: if recovery.conf is linked, it will be written anew as a normal file.
if os.path.islink(self.recovery_conf):
os.unlink(self.recovery_conf)
else:
os.remove(self.recovery_conf)
# Archived segments might be useful to pg_rewind,
# clean the flags that tell we should remove them.
self.cleanup_archive_status()
# Start in a single user mode and stop to produce a clean shutdown
opts = self.read_postmaster_opts()
opts.update({'archive_mode': 'on', 'archive_command': 'false'})
self.single_user_mode(options=opts)
if self.rewind(leader):
ret = self.start()
else:
logger.error("unable to rewind the former master")
self.remove_data_directory()
ret = True
else: # do not rewind until the leader becomes available
ret = self.restart()
if change_role and ret:
self.call_nowait(ACTION_ON_ROLE_CHANGE)
return ret
def save_configuration_files(self):
"""
copy postgresql.conf to postgresql.conf.backup to be able to retrive configuration files
- originally stored as symlinks, those are normally skipped by pg_basebackup
- in case of WAL-E basebackup (see http://comments.gmane.org/gmane.comp.db.postgresql.wal-e/239)
"""
try:
for f in self.configuration_to_save:
if os.path.isfile(f):
shutil.copy(f, f + '.backup')
except IOError:
logger.exception('unable to create backup copies of configuration files')
def restore_configuration_files(self):
""" restore a previously saved postgresql.conf """
try:
for f in self.configuration_to_save:
if not os.path.isfile(f) and os.path.isfile(f + '.backup'):
shutil.copy(f + '.backup', f)
except IOError:
logger.exception('unable to restore configuration files from backup')
def promote(self):
if self.role == 'master':
return True
ret = subprocess.call(self._pg_ctl + ['promote']) == 0
if ret:
self.set_role('master')
logger.info("cleared rewind flag after becoming the leader")
self.call_nowait(ACTION_ON_ROLE_CHANGE)
return ret
def create_or_update_role(self, name, password, options):
self.query("""DO $$
BEGIN
SET local synchronous_commit = 'local';
PERFORM * FROM pg_authid WHERE rolname = %s;
IF FOUND THEN
ALTER ROLE "{0}" WITH LOGIN {1} PASSWORD %s;
ELSE
CREATE ROLE "{0}" WITH LOGIN {1} PASSWORD %s;
END IF;
END;
$$""".format(name, options), name, password, password)
def create_replication_user(self):
self.create_or_update_role(self.replication['username'], self.replication['password'], 'REPLICATION')
def create_connection_user(self):
if self.admin:
self.create_or_update_role(self.admin['username'], self.admin['password'], 'CREATEDB CREATEROLE')
def xlog_position(self):
return self.query("""SELECT pg_xlog_location_diff(CASE WHEN pg_is_in_recovery()
THEN pg_last_xlog_replay_location()
ELSE pg_current_xlog_location()
END, '0/0')::bigint""").fetchone()[0]
def load_replication_slots(self):
if self.use_slots and self.schedule_load_slots:
cursor = self.query("SELECT slot_name FROM pg_replication_slots WHERE slot_type='physical'")
self.replication_slots = [r[0] for r in cursor]
self.schedule_load_slots = False
def sync_replication_slots(self, cluster):
if self.use_slots:
try:
self.load_replication_slots()
# if the replicatefrom tag is set on the member - we should not create the replication slot for it on
# the current master, because that member would replicate from elsewhere. We still create the slot if
# the replicatefrom destination member is currently not a member of the cluster (fallback to the
# master), or if replicatefrom destination member happens to be the current master
if self.role == 'master':
slots = [m.name for m in cluster.members if m.name != self.name and
(m.replicatefrom is None or m.replicatefrom == self.name or
not cluster.has_member(m.replicatefrom))]
else:
# only manage slots for replicas that replicate from this one, except for the leader among them
slots = [m.name for m in cluster.members if m.replicatefrom == self.name and
m.name != cluster.leader.name]
# drop unused slots
for slot in set(self.replication_slots) - set(slots):
self.query("""SELECT pg_drop_replication_slot(%s)
WHERE EXISTS(SELECT 1 FROM pg_replication_slots
WHERE slot_name = %s)""", slot, slot)
# create new slots
for slot in set(slots) - set(self.replication_slots):
self.query("""SELECT pg_create_physical_replication_slot(%s)
WHERE NOT EXISTS (SELECT 1 FROM pg_replication_slots
WHERE slot_name = %s)""", slot, slot)
self.replication_slots = slots
except psycopg2.Error:
logger.exception('Exception when changing replication slots')
def last_operation(self):
return str(self.xlog_position())
def bootstrap(self, cluster_initialized=False, clone_member=None):
"""
Populate PostgreSQL data directory by doing one of the following:
- create with initdb if there is no master.
- initialize the replica from an existing member (master or replica)
- initialize the replica using the replica creation method that
works without the replication connection (i.e. restore from on-disk
base backup)
The choice between the last 2 is triggered by the initialize flag.
We should never try to initdb an already initialized cluster, nor
try to bootstrap the cluster that lacks the initialize key using the
master-less replica creation method (in the latter case, there is
no clear inidicator of the moment we should abandon our attempts and
swich to initdb).
Failure during initdb always leads to an exception, since there is
no point in continuing if initdb fails. For the rest of the cases,
the function returns False in order to inidicate a failed attempt
that should be retried in the future.
"""
ret = False
if not (cluster_initialized or clone_member):
ret = self.initialize() and self.start()
if ret:
self.create_replication_user()
self.create_connection_user()
else:
raise PostgresException("Could not bootstrap master PostgreSQL")
else:
if self.sync_replica(clone_member):
self.restore_configuration_files()
self.write_recovery_conf(clone_member, True)
ret = self.start()
return ret
def move_data_directory(self):
if os.path.isdir(self.data_dir) and not self.is_running():
try:
new_name = '{0}_{1}'.format(self.data_dir, time.strftime('%Y-%m-%d-%H-%M-%S'))
logger.info('renaming data directory to %s', new_name)
os.rename(self.data_dir, new_name)
except OSError:
logger.exception("Could not rename data directory %s", self.data_dir)
def remove_data_directory(self):
logger.info('Removing data directory: %s', self.data_dir)
try:
if os.path.islink(self.data_dir):
os.unlink(self.data_dir)
elif not os.path.exists(self.data_dir):
return
elif os.path.isfile(self.data_dir):
os.remove(self.data_dir)
elif os.path.isdir(self.data_dir):
shutil.rmtree(self.data_dir)
except (IOError, OSError):
logger.exception('Could not remove data directory %s', self.data_dir)
self.move_data_directory()
def basebackup(self, clone_member, env):
# creates a replica data dir using pg_basebackup.
# this is the default, built-in create_replica_method
# tries twice, then returns failure (as 1)
# uses "stream" as the xlog-method to avoid sync issues
master_connection = clone_member.conn_url
maxfailures = 2
ret = 1
for bbfailures in range(0, maxfailures):
try:
ret = subprocess.call(['pg_basebackup', '--pgdata=' + self.data_dir,
'--xlog-method=stream', "--dbname=" + master_connection], env=env)
if ret == 0:
break
except Exception as e:
logger.error('Error when fetching backup with pg_basebackup: {0}'.format(e))
if bbfailures < maxfailures - 1:
logger.error('Trying again in 5 seconds')
time.sleep(5)
return ret