def protect_host(hostname, reason):
""" Cause an host to not be acted on by the retirement queue
Args:
hostname - The hostname to protect
reason - An explanation for why this host should not be retired
dry_run - If set, don't modify state
"""
protecting_user = host_utils.get_user()
if protecting_user == 'root':
raise Exception('Can not modify retirement protection as root')
reporting_conn = mysql_lib.get_mysqlops_connections()
cursor = reporting_conn.cursor()
sql = ("INSERT INTO mysqlops.retirement_protection "
"SET "
"hostname = %(hostname)s, "
"reason = %(reason)s, "
"protecting_user = %(protecting_user)s")
cursor.execute(sql, {
'hostname': hostname,
'reason': reason,
'protecting_user': protecting_user
})
reporting_conn.commit()
log.info(cursor._executed)
def get_promotion_lock(replica_set):
""" Take a promotion lock
Args:
replica_set - The replica set to take the lock against
Returns:
A unique identifer for the lock
"""
lock_identifier = str(uuid.uuid4())
log.info('Promotion lock identifier is '
'{lock_identifier}'.format(lock_identifier=lock_identifier))
conn = mysql_lib.get_mysqlops_connections()
log.info('Releasing any expired locks')
release_expired_promotion_locks(conn)
log.info('Checking existing locks')
check_promotion_lock(conn, replica_set)
log.info('Taking lock against replica set: '
'{replica_set}'.format(replica_set=replica_set))
params = {
'lock': lock_identifier,
'localhost': host_utils.HOSTNAME,
'replica_set': replica_set,
'user': host_utils.get_user()
}
sql = ("INSERT INTO mysqlops.promotion_locks "
"SET "
"lock_identifier = %(lock)s, "
"lock_active = 'active', "
"created_at = NOW(), "
"expires = NOW() + INTERVAL 12 HOUR, "
"released = NULL, "
"replica_set = %(replica_set)s, "
"promoting_host = %(localhost)s, "
"promoting_user = %(user)s ")
cursor = conn.cursor()
cursor.execute(sql, params)
conn.commit()
log.info(cursor._executed)
return lock_identifier
def get_promotion_lock(replica_set):
""" Take a promotion lock
Args:
replica_set - The replica set to take the lock against
Returns:
A unique identifer for the lock
"""
lock_identifier = str(uuid.uuid4())
log.info('Promotion lock identifier is '
'{lock_identifier}'.format(lock_identifier=lock_identifier))
conn = mysql_lib.get_mysqlops_connections()
log.info('Releasing any expired locks')
release_expired_promotion_locks(conn)
log.info('Checking existing locks')
check_promotion_lock(conn, replica_set)
log.info('Taking lock against replica set: '
'{replica_set}'.format(replica_set=replica_set))
params = {'lock': lock_identifier,
'localhost': host_utils.HOSTNAME,
'replica_set': replica_set,
'user': host_utils.get_user()}
sql = ("INSERT INTO mysqlops.promotion_locks "
"SET "
"lock_identifier = %(lock)s, "
"lock_active = 'active', "
"created_at = NOW(), "
"expires = NOW() + INTERVAL 12 HOUR, "
"released = NULL, "
"replica_set = %(replica_set)s, "
"promoting_host = %(localhost)s, "
"promoting_user = %(user)s ")
cursor = conn.cursor()
cursor.execute(sql, params)
conn.commit()
log.info(cursor._executed)
return lock_identifier
def protect_host(hostname, reason):
""" Cause an host to not be acted on by the retirement queue
Args:
hostname - The hostname to protect
reason - An explanation for why this host should not be retired
dry_run - If set, don't modify state
"""
protecting_user = host_utils.get_user()
if protecting_user == 'root':
raise Exception('Can not modify retirement protection as root')
reporting_conn = mysql_lib.get_mysqlops_connections()
cursor = reporting_conn.cursor()
sql = ("INSERT INTO mysqlops.retirement_protection "
"SET "
"hostname = %(hostname)s, "
"reason = %(reason)s, "
"protecting_user = %(protecting_user)s")
cursor.execute(sql, {'hostname': hostname,
'reason': reason,
'protecting_user': protecting_user})
reporting_conn.commit()
log.info(cursor._executed)
def mysql_failover(master, dry_run, skip_lock, ignore_dr_slave,
trust_me_its_dead, kill_old_master):
""" Promote a new MySQL master
Args:
master - Hostaddr object of the master instance to be demoted
dry_run - Do not change state, just do sanity testing and exit
skip_lock - Do not take a promotion lock
ignore_dr_slave - Ignore the existance of a dr_slave
trust_me_its_dead - Do not test to see if the master is dead
kill_old_master - Send a mysqladmin kill command to the old master
Returns:
new_master - The new master server
"""
log.info('Master to demote is {master}'.format(master=master))
zk = host_utils.MysqlZookeeper()
(replica_set, _) = zk.get_replica_set_from_instance(master,
rtypes=['master'])
log.info('Replica set is detected as '
'{replica_set}'.format(replica_set=replica_set))
# take a lock here to make sure nothing changes underneath us
if not skip_lock and not dry_run:
log.info('Taking promotion lock on replica set')
lock_identifier = get_promotion_lock(replica_set)
else:
lock_identifier = None
# giant try. If there any problems we roll back from the except
try:
master_conn = False
slave = zk.get_mysql_instance_from_replica_set(
replica_set=replica_set, repl_type=host_utils.REPLICA_ROLE_SLAVE)
log.info('Slave/new master is detected as {slave}'.format(slave=slave))
if ignore_dr_slave:
log.info('Intentionally ignoring a dr_slave')
dr_slave = None
else:
dr_slave = zk.get_mysql_instance_from_replica_set(
replica_set, host_utils.REPLICA_ROLE_DR_SLAVE)
log.info(
'DR slave is detected as {dr_slave}'.format(dr_slave=dr_slave))
if dr_slave:
if dr_slave == slave:
raise Exception('Slave and dr_slave appear to be the same')
replicas = set([slave, dr_slave])
else:
replicas = set([slave])
# We use master_conn as a mysql connection to the master server, if
# it is False, the master is dead
if trust_me_its_dead:
master_conn = None
else:
master_conn = is_master_alive(master, replicas)
# Test to see if the slave is setup for replication. If not, we are hosed
log.info('Testing to see if Slave/new master is setup to write '
'replication logs')
mysql_lib.get_master_status(slave)
if kill_old_master and not dry_run:
log.info('Killing old master, we hope you know what you are doing')
mysql_lib.shutdown_mysql(master)
master_conn = None
if master_conn:
log.info('Master is considered alive')
dead_master = False
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_NORMAL,
dead_master)
else:
log.info('Master is considered dead')
dead_master = True
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_LOOSE,
dead_master)
if dry_run:
log.info('In dry_run mode, so exiting now')
# Using os._exit in order to not get catch in the giant try
os._exit(environment_specific.DRY_RUN_EXIT_CODE)
log.info('Preliminary sanity checks complete, starting promotion')
if master_conn:
log.info('Setting read_only on master')
mysql_lib.set_global_variable(master, 'read_only', True)
log.info('Confirming no writes to old master')
# If there are writes with the master in read_only mode then the
# promotion can not proceed.
# A likely reason is a client has the SUPER privilege.
confirm_no_writes(master)
log.info('Waiting for replicas to be caught up')
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_NONE,
dead_master, True,
mysql_lib.NORMAL_HEARTBEAT_LAG)
log.info('Setting up replication from old master ({master}) '
'to new master ({slave})'.format(master=master,
slave=slave))
mysql_lib.setup_replication(new_master=slave, new_replica=master)
else:
log.info('Starting up a zk connection to make sure we can connect')
kazoo_client = environment_specific.get_kazoo_client()
if not kazoo_client:
raise Exception('Could not conect to zk')
log.info('Confirming replica has processed all replication '
' logs')
confirm_no_writes(slave)
log.info('Looks like no writes being processed by replica via '
'replication or other means')
if len(replicas) > 1:
log.info('Confirming replica servers are synced')
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_LOOSE,
dead_master, True)
except:
log.info('Starting rollback')
if master_conn:
log.info('Releasing read_only on old master')
mysql_lib.set_global_variable(master, 'read_only', False)
log.info('Clearing replication settings on old master')
mysql_lib.reset_slave(master)
if lock_identifier:
log.info('Releasing promotion lock')
release_promotion_lock(lock_identifier)
log.info('Rollback complete, reraising exception')
raise
if dr_slave:
try:
mysql_lib.setup_replication(new_master=slave, new_replica=dr_slave)
except Exception as e:
log.error(e)
log.error('Setting up replication on the dr_slave failed. '
'Failing forward!')
log.info('Updating zk')
zk_write_attempt = 0
while True:
try:
modify_mysql_zk.swap_master_and_slave(slave, dry_run=False)
break
except:
if zk_write_attempt > MAX_ZK_WRITE_ATTEMPTS:
log.info('Final failure writing to zk, bailing')
raise
else:
log.info('Write to zk failed, trying again')
zk_write_attempt = zk_write_attempt + 1
log.info('Removing read_only from new master')
mysql_lib.set_global_variable(slave, 'read_only', False)
log.info('Removing replication configuration from new master')
mysql_lib.reset_slave(slave)
if lock_identifier:
log.info('Releasing promotion lock')
release_promotion_lock(lock_identifier)
log.info('Failover complete')
# we don't really care if this fails, but we'll print a message anyway.
try:
environment_specific.generic_json_post(
environment_specific.CHANGE_FEED_URL, {
'type': 'MySQL Failover',
'environment': replica_set,
'description': "Failover from {m} to {s}".format(m=master,
s=slave),
'author': host_utils.get_user(),
'automation': False,
'source': "mysql_failover.py on {}".format(host_utils.HOSTNAME)
})
except Exception as e:
log.warning("Failover completed, but change feed "
"not updated: {}".format(e))
if not master_conn:
log.info('As master is dead, will try to launch a replacement. Will '
'sleep 20 seconds first to let things settle')
time.sleep(20)
launch_replacement_db_host.launch_replacement_db_host(master)
def mysql_failover(master, dry_run, skip_lock,
ignore_dr_slave, trust_me_its_dead, kill_old_master):
""" Promote a new MySQL master
Args:
master - Hostaddr object of the master instance to be demoted
dry_run - Do not change state, just do sanity testing and exit
skip_lock - Do not take a promotion lock
ignore_dr_slave - Ignore the existance of a dr_slave
trust_me_its_dead - Do not test to see if the master is dead
kill_old_master - Send a mysqladmin kill command to the old master
Returns:
new_master - The new master server
"""
log.info('Master to demote is {master}'.format(master=master))
zk = host_utils.MysqlZookeeper()
(replica_set, _) = zk.get_replica_set_from_instance(master, rtypes=['master'])
log.info('Replica set is detected as '
'{replica_set}'.format(replica_set=replica_set))
# take a lock here to make sure nothing changes underneath us
if not skip_lock and not dry_run:
log.info('Taking promotion lock on replica set')
lock_identifier = get_promotion_lock(replica_set)
else:
lock_identifier = None
# giant try. If there any problems we roll back from the except
try:
master_conn = False
slave = zk.get_mysql_instance_from_replica_set(replica_set=replica_set,
repl_type=host_utils.REPLICA_ROLE_SLAVE)
log.info('Slave/new master is detected as {slave}'.format(slave=slave))
if ignore_dr_slave:
log.info('Intentionally ignoring a dr_slave')
dr_slave = None
else:
dr_slave = zk.get_mysql_instance_from_replica_set(replica_set,
host_utils.REPLICA_ROLE_DR_SLAVE)
log.info('DR slave is detected as {dr_slave}'.format(dr_slave=dr_slave))
if dr_slave:
if dr_slave == slave:
raise Exception('Slave and dr_slave appear to be the same')
replicas = set([slave, dr_slave])
else:
replicas = set([slave])
# We use master_conn as a mysql connection to the master server, if
# it is False, the master is dead
if trust_me_its_dead:
master_conn = None
else:
master_conn = is_master_alive(master, replicas)
# Test to see if the slave is setup for replication. If not, we are hosed
log.info('Testing to see if Slave/new master is setup to write '
'replication logs')
mysql_lib.get_master_status(slave)
if kill_old_master and not dry_run:
log.info('Killing old master, we hope you know what you are doing')
mysql_lib.shutdown_mysql(master)
master_conn = None
if master_conn:
log.info('Master is considered alive')
dead_master = False
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_NORMAL,
dead_master)
else:
log.info('Master is considered dead')
dead_master = True
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_LOOSE,
dead_master)
if dry_run:
log.info('In dry_run mode, so exiting now')
# Using os._exit in order to not get catch in the giant try
os._exit(0)
log.info('Preliminary sanity checks complete, starting promotion')
if master_conn:
log.info('Setting read_only on master')
mysql_lib.set_global_variable(master, 'read_only', True)
log.info('Confirming no writes to old master')
# If there are writes with the master in read_only mode then the
# promotion can not proceed.
# A likely reason is a client has the SUPER privilege.
confirm_no_writes(master)
log.info('Waiting for replicas to be caught up')
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_NONE,
dead_master,
True,
mysql_lib.NORMAL_HEARTBEAT_LAG)
log.info('Setting up replication from old master ({master}) '
'to new master ({slave})'.format(master=master,
slave=slave))
mysql_lib.setup_replication(new_master=slave, new_replica=master)
else:
log.info('Starting up a zk connection to make sure we can connect')
kazoo_client = environment_specific.get_kazoo_client()
if not kazoo_client:
raise Exception('Could not conect to zk')
log.info('Confirming replica has processed all replication '
' logs')
confirm_no_writes(slave)
log.info('Looks like no writes being processed by replica via '
'replication or other means')
if len(replicas) > 1:
log.info('Confirming replica servers are synced')
confirm_max_replica_lag(replicas,
mysql_lib.REPLICATION_TOLERANCE_LOOSE,
dead_master,
True)
except:
log.info('Starting rollback')
if master_conn:
log.info('Releasing read_only on old master')
mysql_lib.set_global_variable(master, 'read_only', False)
log.info('Clearing replication settings on old master')
mysql_lib.reset_slave(master)
if lock_identifier:
log.info('Releasing promotion lock')
release_promotion_lock(lock_identifier)
log.info('Rollback complete, reraising exception')
raise
if dr_slave:
try:
mysql_lib.setup_replication(new_master=slave, new_replica=dr_slave)
except Exception as e:
log.error(e)
log.error('Setting up replication on the dr_slave failed. '
'Failing forward!')
log.info('Updating zk')
zk_write_attempt = 0
while True:
try:
modify_mysql_zk.swap_master_and_slave(slave, dry_run=False)
break
except:
if zk_write_attempt > MAX_ZK_WRITE_ATTEMPTS:
log.info('Final failure writing to zk, bailing')
raise
else:
log.info('Write to zk failed, trying again')
zk_write_attempt = zk_write_attempt+1
log.info('Removing read_only from new master')
mysql_lib.set_global_variable(slave, 'read_only', False)
log.info('Removing replication configuration from new master')
mysql_lib.reset_slave(slave)
if lock_identifier:
log.info('Releasing promotion lock')
release_promotion_lock(lock_identifier)
log.info('Failover complete')
# we don't really care if this fails, but we'll print a message anyway.
try:
environment_specific.generic_json_post(
environment_specific.CHANGE_FEED_URL,
{'type': 'MySQL Failover',
'environment': replica_set,
'description': "Failover from {m} to {s}".format(m=master, s=slave),
'author': host_utils.get_user(),
'automation': False,
'source': "mysql_failover.py on {}".format(host_utils.HOSTNAME)})
except Exception as e:
log.warning("Failover completed, but change feed "
"not updated: {}".format(e))
if not master_conn:
log.info('As master is dead, will try to launch a replacement. Will '
'sleep 20 seconds first to let things settle')
time.sleep(20)
launch_replacement_db_host.launch_replacement_db_host(master)
