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Implement validated restart on change

Add new metadata cache parameters.
Use the charm-helpers' pausable_restart_on_change for config-changed
Validate connectivity on restart to resolve LP Bug #1915842

See "Metadata Cache Options"
https://dev.mysql.com/doc/mysql-router/8.0/en/mysql-router-conf-options.html

Closes-Bug: #1915842
Change-Id: Icd30f9ade2c7aadbadaa57300c22786cde63957f
changes/64/776764/4
David Ames 1 year ago
parent
commit
80339e4625
  1. 24
      src/config.yaml
  2. 159
      src/lib/charm/openstack/mysql_router.py
  3. 1
      src/reactive/mysql_router_handlers.py
  4. 1
      src/wheelhouse.txt
  5. 64
      unit_tests/test_lib_charm_openstack_mysql_router.py

24
src/config.yaml

@ -20,3 +20,27 @@ options:
description: |
Base port number for RW interface. RO, xRW and xRO will
increment from base_port.
ttl:
type: float
default: .5
description: |
Time to live (in seconds) of information in the metadata cache.
Accepts either an integer or a floating point value. The granularity is
limited to milliseconds, where 0.001 equates to one millisecond.
Precision is truncated to the supported range; for example ttl=0.0119
is treated as 11 milliseconds. The value 0 means that the metadata
cache module queries the metadata continuously in a tight loop.
auth_cache_refresh_interval:
type: int
default: 2
description: |
Time (in seconds) between the auth-cache refresh attempts. Defaults to
2. The value must be smaller than auth_cache_ttl and ttl else Router
won't start.
auth_cache_ttl:
type: int
default: -1
description: |
Time (in seconds) until the cache becomes invalid if not refreshed.
Defaults to -1 (infinite). The value must be larger than
auth_cache_refresh_interval else Router won't start.

159
src/lib/charm/openstack/mysql_router.py

@ -16,6 +16,7 @@ import configparser
import json
import os
import subprocess
import tenacity
import charms_openstack.charm
import charms_openstack.adapters
@ -28,6 +29,7 @@ import charmhelpers.contrib.network.ip as ch_net_ip
import charmhelpers.contrib.database.mysql as mysql
import charmhelpers.contrib.openstack.templating as os_templating
import charmhelpers.contrib.openstack.utils as os_utils
# Flag Strings
@ -74,6 +76,10 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
# For internal use with mysql.get_db_data
_unprefixed = "MRUP"
# mysql.MySQLdb._exceptions.OperationalError error 2013
# LP Bug #1915842
_waiting_for_initial_communication_packet_error = 2013
@property
def mysqlrouter_bin(self):
"""Determine the path to the mysqlrouter binary.
@ -218,6 +224,24 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
def mysqlrouter_group(self):
return "mysql"
@property
def ssl_ca(self):
"""Return the SSL Certificate Authority
:param self: Self
:type self: MySQLInnoDBClusterCharm instance
:returns: Cluster username
:rtype: str
:rtype: Union[str, None]
"""
if self.db_router_endpoint:
if self.db_router_endpoint.ssl_ca():
return json.loads(self.db_router_endpoint.ssl_ca())
@property
def restart_functions(self):
return {self.name: self.custom_restart_function}
def install(self):
"""Custom install function.
@ -313,12 +337,16 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
return states_to_check
def check_mysql_connection(self):
def check_mysql_connection(self, reraise_on=None):
"""Check if an instance of MySQL is accessible.
Attempt a connection to the given instance of mysql to determine if it
is running and accessible.
:param reraise_on: List of integer error codes to reraise exceptions.
For use with tenacity retries on specific
exceptions.
:type reraise_on: List[int]
:side effect: Uses get_db_helper to execute a connection to the DB.
:returns: True if connection succeeds or False if not
:rtype: boolean
@ -331,9 +359,13 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
port=self.mysqlrouter_port,
connect_timeout=self.mysql_connect_timeout)
return True
except mysql.MySQLdb._exceptions.OperationalError:
except mysql.MySQLdb._exceptions.OperationalError as e:
ch_core.hookenv.log("Could not connect to db", "DEBUG")
return False
if not reraise_on:
return False
else:
if e.args[0] in reraise_on:
raise e
def custom_assess_status_check(self):
"""Custom assess status check.
@ -524,19 +556,11 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
_ssl_ca = receiving_interface.ssl_ca()
if _ssl_ca:
_ssl_ca = json.loads(_ssl_ca)
# We are using CA signed certificates with validation for TLS
# Set client_ssl_mode = PASSTHROUGH
self.update_config_parameter(
"DEFAULT", "client_ssl_mode", "PASSTHROUGH")
else:
# Reset ssl_ca in case we previously had it set
ch_core.hookenv.log("Proactively resetting ssl_ca", "DEBUG")
sending_interface.relations[
unit.relation.relation_id].to_publish_raw["ssl_ca"] = None
# We are using self-signed certificates for TLS
# Set client_ssl_mode = PREFERRED
self.update_config_parameter(
"DEFAULT", "client_ssl_mode", "PREFERRED")
if ch_core.hookenv.local_unit() in (json.loads(
receiving_interface.allowed_units(prefix=prefix))):
@ -556,29 +580,100 @@ class MySQLRouterCharm(charms_openstack.charm.OpenStackCharm):
db_port=self.mysqlrouter_port,
ssl_ca=_ssl_ca)
def update_config_parameter(self, heading, param, value):
"""Update configuration parameter.
Update this instances mysqlrouter.conf with a key=value.
Such that under heading we get param = value.
Restart on changed based on the mysqlrouter.conf.
:param heading: The config file heading i.e. 'DEFAULT'
:type heading: str
:param param: The parameter key
:type param: str
:param value: The value getting set
:type value: str
:side effect: Writes the mysqlrouter.conf file and restarts services if
there is a change.
def update_config_parameters(self, parameters):
"""Update configuration parameters using ConfigParser.
Update this instances mysqlrouter.conf with a dictionary set of
configuration parameters and values of the form:
parameters = {
"HEADING": {
"param": "value"
}
}
:param parameters: Dictionary of parameters
:type parameters: dict
:side effect: Writes the mysqlrouter.conf file
:returns: This function is called for its side effect
:rtype: None
"""
config = configparser.ConfigParser()
config.read(self.mysqlrouter_conf)
config[heading][param] = value
ch_core.hookenv.log("Updating {} with {} {} = {}".format(
self.mysqlrouter_conf, heading, param, value))
with self.restart_on_change():
with open(self.mysqlrouter_conf, 'w') as configfile:
config.write(configfile)
for heading in parameters.keys():
for param in parameters[heading].keys():
config[heading][param] = parameters[heading][param]
ch_core.hookenv.log("Writing {}".format(
self.mysqlrouter_conf))
with open(self.mysqlrouter_conf, 'w') as configfile:
config.write(configfile)
def config_changed(self):
"""Config changed.
Custom config changed as we are not using templates we need to update
config via ConfigParser. We only update after the mysql-router service
has bootstrapped.
:side effect: Calls update_config_parameter and restarts mysql-router
if the config file has changed.
:returns: This function is called for its side effect
:rtype: None
"""
if not os.path.exists(self.mysqlrouter_conf):
ch_core.hookenv.log(
"mysqlrouter.conf does not yet exist. "
"Skipping config changed.", "DEBUG")
return
_parameters = {
"metadata_cache:jujuCluster": {
"ttl": str(self.options.ttl),
"auth_cache_ttl": str(self.options.auth_cache_ttl),
"auth_cache_refresh_interval":
str(self.options.auth_cache_refresh_interval),
}
}
if self.ssl_ca:
ch_core.hookenv.log("TLS mode PASSTHROUGH", "DEBUG")
_parameters["DEFAULT"] = {"client_ssl_mode": "PASSTHROUGH"}
else:
ch_core.hookenv.log("TLS mode PREFERRED", "DEBUG")
_parameters["DEFAULT"] = {"client_ssl_mode": "PREFERRED"}
# NOTE: LP Bug #1917792
# Switch to context manager when work there is completed
@os_utils.pausable_restart_on_change(
self.restart_map, restart_functions=self.restart_functions)
def _config_changed(self, parameters):
ch_core.hookenv.log("Updating configuration parameters", "DEBUG")
self.update_config_parameters(parameters)
_config_changed(self, _parameters)
@tenacity.retry(wait=tenacity.wait_fixed(10),
retry=tenacity.retry_if_exception_type(
mysql.MySQLdb._exceptions.OperationalError),
reraise=True,
stop=tenacity.stop_after_attempt(5))
def custom_restart_function(self, service_name):
"""Tenacity retry custom restart function for restart_on_change
Custom restart function for use in restart_on_change contexts. Tenacity
retry enabled based on verification of connectivity.
:side effect: Calls service_stop and service_start on the mysql-router
service(s).
:returns: This function is called for its side effect
:rtype: None
"""
ch_core.hookenv.log(
"Custom restart of {}".format(service_name), "DEBUG")
self.service_stop(service_name)
self.service_start(service_name)
# Only raise an exception if it matches
# mysql.MySQLdb._exceptions.OperationalError error 2013
# LP Bug #1915842
self.check_mysql_connection(
reraise_on=[self._waiting_for_initial_communication_packet_error])

1
src/reactive/mysql_router_handlers.py

@ -99,5 +99,6 @@ def proxy_shared_db_responses(shared_db, db_router):
:type db_router_interface: MySQLRouterRequires object
"""
with charm.provide_charm_instance() as instance:
instance.config_changed()
instance.proxy_db_and_user_responses(db_router, shared_db)
instance.assess_status()

1
src/wheelhouse.txt

@ -1,5 +1,6 @@
psutil
mysqlclient
tenacity
git+https://github.com/juju/charm-helpers.git#egg=charmhelpers

64
unit_tests/test_lib_charm_openstack_mysql_router.py

@ -600,15 +600,75 @@ class TestMySQLRouterCharm(test_utils.PatchHelper):
self.db_router, self.keystone_shared_db)
self.keystone_shared_db.set_db_connection_info.assert_not_called()
def test_update_config_parameter(self):
def test_update_config_parameters(self):
self.patch_object(mysql_router.configparser, "ConfigParser")
self.service_name = "mysql-router"
_mock_config_parser = mock.MagicMock()
self.ConfigParser.return_value = _mock_config_parser
_params = {"DEFAULT": {"client_ssl_mode": "PREFERRED"}}
mrc = mysql_router.MySQLRouterCharm()
mrc.update_config_parameter("DEFAULT", "client_ssl_mode", "PREFERRED")
mrc.update_config_parameters(_params)
_mock_config_parser.read.assert_called_once()
_mock_config_parser.__getitem__.assert_called_once_with('DEFAULT')
_mock_config_parser.__getitem__().__setitem__.assert_called_once_with(
'client_ssl_mode', 'PREFERRED')
_mock_config_parser.write.assert_called_once_with(
self.mock_open()().__enter__())
def test_config_changed(self):
_config_data = {
"ttl": '5',
"auth_cache_ttl": '10',
"auth_cache_refresh_interval": '7',
}
_mock_decorator = mock.MagicMock()
_mock_decorated = mock.MagicMock()
_mock_decorator.return_value = _mock_decorated
def _fake_config(key=None):
return _config_data[key] if key else _config_data
self.patch_object(mysql_router.ch_core.hookenv, "config")
self.patch_object(mysql_router.os.path, "exists")
self.patch_object(mysql_router.os_utils, "pausable_restart_on_change")
self.config.side_effect = _fake_config
self.pausable_restart_on_change.return_value = _mock_decorator
self.service_name = "mysql-router"
self.endpoint_from_flag.return_value = self.db_router
self.db_router.ssl_ca.return_value = '"CACERT"'
_mock_update_config_parameters = mock.MagicMock()
mrc = mysql_router.MySQLRouterCharm()
mrc.update_config_parameters = _mock_update_config_parameters
_params = {
'metadata_cache:jujuCluster': _config_data,
'DEFAULT': {'client_ssl_mode': "PASSTHROUGH"},
}
# Not bootstrapped yet
self.exists.return_value = False
mrc.config_changed()
_mock_update_config_parameters.assert_not_called()
# Bootstrapped
self.exists.return_value = True
mrc.config_changed()
_mock_decorated.assert_has_calls([mock.call(mrc, _params)])
def test_custom_restart_function(self):
self.patch_object(mysql_router.ch_core.host, "service_stop")
self.patch_object(mysql_router.ch_core.host, "service_start")
self.service_name = "mysql-router"
_mock_check_mysql_connection = mock.MagicMock()
mrc = mysql_router.MySQLRouterCharm()
mrc.check_mysql_connection = _mock_check_mysql_connection
mrc.custom_restart_function(self.service_name)
self.service_stop.assert_called_once_with(self.service_name)
self.service_start.assert_called_once_with(self.service_name)
_mock_check_mysql_connection.assert_called_once()

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