87 lines
2.9 KiB
Python

"""Database configuration functions."""
import logging
from pymongo.errors import OperationFailure
from bigchaindb.backend import admin
from bigchaindb.backend.utils import module_dispatch_registrar
from bigchaindb.backend.exceptions import OperationError
from bigchaindb.backend.mongodb.connection import MongoDBConnection
logger = logging.getLogger(__name__)
register_admin = module_dispatch_registrar(admin)
@register_admin(MongoDBConnection)
def add_replicas(connection, replicas):
"""Add a set of replicas to the replicaset
Args:
connection (:class:`~bigchaindb.backend.connection.Connection`):
A connection to the database.
replicas (:obj:`list` of :obj:`str`): replica addresses in the
form "hostname:port".
Raises:
OperationError: If the reconfiguration fails due to a MongoDB
:exc:`OperationFailure`
"""
# get current configuration
conf = connection.conn.admin.command('replSetGetConfig')
# MongoDB does not automatically add an id for the members so we need
# to choose one that does not exist yet. The safest way is to use
# incrementing ids, so we first check what is the highest id already in
# the set and continue from there.
cur_id = max([member['_id'] for member in conf['config']['members']])
# add the nodes to the members list of the replica set
for replica in replicas:
cur_id += 1
conf['config']['members'].append({'_id': cur_id, 'host': replica})
# increase the configuration version number
# when reconfiguring, mongodb expects a version number higher than the one
# it currently has
conf['config']['version'] += 1
# apply new configuration
try:
connection.conn.admin.command('replSetReconfig', conf['config'])
except OperationFailure as exc:
raise OperationError(exc.details['errmsg'])
@register_admin(MongoDBConnection)
def remove_replicas(connection, replicas):
"""Remove a set of replicas from the replicaset
Args:
connection (:class:`~bigchaindb.backend.connection.Connection`):
A connection to the database.
replicas (:obj:`list` of :obj:`str`): replica addresses in the
form "hostname:port".
Raises:
OperationError: If the reconfiguration fails due to a MongoDB
:exc:`OperationFailure`
"""
# get the current configuration
conf = connection.conn.admin.command('replSetGetConfig')
# remove the nodes from the members list in the replica set
conf['config']['members'] = list(
filter(lambda member: member['host'] not in replicas,
conf['config']['members'])
)
# increase the configuration version number
conf['config']['version'] += 1
# apply new configuration
try:
connection.conn.admin.command('replSetReconfig', conf['config'])
except OperationFailure as exc:
raise OperationError(exc.details['errmsg'])