openstack/neutron
Code Issues Proposed changes
fb54054a80
neutron/neutron/tests/unit/bigswitch/test_ssl.py
Kevin Benton 615e2d6399 BSN: Optimistic locking strategy for consistency 
Summary:
  Adds an optimistic locking strategy for the Big Switch
  server manager so multiple Neutron servers wanting to
  communicate with the backend do not receive the consistency
  hash for use simultaneously.

  The bsn-rest-call semaphore is removed because serialization
  is now provided by the new locking scheme.

  A new DB engine is added because the consistency hashes
  need a life-cycle with rollbacks and other DB operations
  than cannot impact or be impacted by database operations
  happening on the regular Neutron objects.

  Unit tests are included for each of the new branches
  introduced.

Problem Statement:
  Requests to the Big Switch controllers must contain the
  consistency hash value received from the previous update.
  Otherwise, an inconsistency error will be triggered which
  will force a synchronization. Essentially, a new backend
  call must be prevented from reading from the consistency
  hash table in the DB until the previous call has updated
  the table with the hash from the server response.

  This can be addressed by a semaphore around the rest_call
  function for the single server use case and by a table lock
  on the consistency table for multiple Neutron servers.
  However, both solutions are inadequate because a single
  Neutron server does not scale and a table lock is not
  supported by common SQL HA deployments (e.g. Galera).

  This issue was previously addressed by deploying servers
  in an active-standby configuration. However, that only
  prevented the problem for HTTP API calls. All Neutron
  servers would respond to RPC messages, some of which would
  result in a port update and possible backend call which
  would trigger a conflict if it happened at the same time
  as a backend call from another server. These unnecessary
  syncs are unsustainable as the topology increases beyond
  ~3k VMs.

  Any solution needs to be back-portable to Icehouse so new
  database tables, new requirements, etc. are all out of the
  question.

Solution:
  This patch stores the lock for the consistency hash as a part
  of the DB record. The guaruntees the database offers around
  atomic insertion and constrained atomic updates offer the
  primitives necessary to ensure that only one process/thread
  can lock the record at once.

  The read_for_update method is modified to not return the hash
  in the database until an identifier is inserted into the
  current record or added as a new record. By using an UPDATE
  query with a WHERE clause restricting to the current state,
  only one of many concurrent callers to the DB will successfully
  update the rows. If a caller sees that it didn't update any
  rows, it will start the process over of trying to get the
  lock.

  If a caller observes that the same ID has the lock for
  more than 60 seconds, it will assume the holder has
  died and will attempt to take the lock. This is also done
  in a concurrency-safe UPDATE call since there may be many
  other callers may attempt to do the same thing. If it
  fails and the lock was taken by someone else, the process
  will start over.

  Some pseudo-code resembling the logic:
    read_current_lock
    if no_record:
      insert_lock
      sleep_and_retry if constraint_violation else return
    if current_is_locked and not timer_exceeded:
      sleep_and_retry
    if update_record_with_lock:
      return
    else:
      sleep_and_retry

Conflicts:
	neutron/tests/unit/bigswitch/test_servermanager.py

Closes-Bug: #1374261
Change-Id: Ifa5a7c9749952bc2785a9bf3fed69ad55bf21acc
(cherry picked from commit cdaa502f89)
2014-11-21 01:34:26 -08:00

251 lines
10 KiB
Python
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# Copyright 2014 Big Switch Networks, Inc. All rights reserved.
#
# 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 contextlib
import os
import ssl
import mock
from oslo.config import cfg
import webob.exc
from neutron.openstack.common import log as logging
from neutron.tests.unit.bigswitch import fake_server
from neutron.tests.unit.bigswitch import test_base
from neutron.tests.unit import test_api_v2
from neutron.tests.unit import test_db_plugin as test_plugin
LOG = logging.getLogger(__name__)
SERVERMANAGER = 'neutron.plugins.bigswitch.servermanager'
HTTPS = SERVERMANAGER + '.HTTPSConnectionWithValidation'
CERTCOMBINER = SERVERMANAGER + '.ServerPool._combine_certs_to_file'
FILEPUT = SERVERMANAGER + '.ServerPool._file_put_contents'
GETCACERTS = SERVERMANAGER + '.ServerPool._get_ca_cert_paths'
GETHOSTCERT = SERVERMANAGER + '.ServerPool._get_host_cert_path'
SSLGETCERT = SERVERMANAGER + '.ssl.get_server_certificate'
FAKECERTGET = 'neutron.tests.unit.bigswitch.fake_server.get_cert_contents'
class test_ssl_certificate_base(test_plugin.NeutronDbPluginV2TestCase,
test_base.BigSwitchTestBase):
plugin_str = ('%s.NeutronRestProxyV2' %
test_base.RESTPROXY_PKG_PATH)
servername = None
cert_base = None
def _setUp(self):
self.servername = test_api_v2._uuid()
self.cert_base = cfg.CONF.RESTPROXY.ssl_cert_directory
self.host_cert_val = 'DUMMYCERTFORHOST%s' % self.servername
self.host_cert_path = os.path.join(
self.cert_base,
'host_certs',
'%s.pem' % self.servername
)
self.comb_cert_path = os.path.join(
self.cert_base,
'combined',
'%s.pem' % self.servername
)
self.ca_certs_path = os.path.join(
self.cert_base,
'ca_certs'
)
cfg.CONF.set_override('servers', ["%s:443" % self.servername],
'RESTPROXY')
self.setup_patches()
# Mock method SSL lib uses to grab cert from server
self.sslgetcert_m = mock.patch(SSLGETCERT, create=True).start()
self.sslgetcert_m.return_value = self.host_cert_val
# Mock methods that write and read certs from the file-system
self.fileput_m = mock.patch(FILEPUT, create=True).start()
self.certcomb_m = mock.patch(CERTCOMBINER, create=True).start()
self.getcacerts_m = mock.patch(GETCACERTS, create=True).start()
# this is used to configure what certificate contents the fake HTTPS
# lib should expect to receive
self.fake_certget_m = mock.patch(FAKECERTGET, create=True).start()
def setUp(self):
super(test_ssl_certificate_base, self).setUp(self.plugin_str)
self.setup_db()
class TestSslSticky(test_ssl_certificate_base):
def setUp(self):
self.setup_config_files()
cfg.CONF.set_override('server_ssl', True, 'RESTPROXY')
cfg.CONF.set_override('ssl_sticky', True, 'RESTPROXY')
self._setUp()
# Set fake HTTPS connection's expectation
self.fake_certget_m.return_value = self.host_cert_val
# No CA certs for this test
self.getcacerts_m.return_value = []
super(TestSslSticky, self).setUp()
def test_sticky_cert(self):
# SSL connection should be successful and cert should be cached
with contextlib.nested(
mock.patch(HTTPS, new=fake_server.HTTPSHostValidation),
self.network()
):
# CA certs should have been checked for
self.getcacerts_m.assert_has_calls([mock.call(self.ca_certs_path)])
# cert should have been fetched via SSL lib
self.sslgetcert_m.assert_has_calls(
[mock.call((self.servername, 443),
ssl_version=ssl.PROTOCOL_TLSv1)]
)
# cert should have been recorded
self.fileput_m.assert_has_calls([mock.call(self.host_cert_path,
self.host_cert_val)])
# no ca certs, so host cert only for this combined cert
self.certcomb_m.assert_has_calls([mock.call([self.host_cert_path],
self.comb_cert_path)])
class TestSslHostCert(test_ssl_certificate_base):
def setUp(self):
self.setup_config_files()
cfg.CONF.set_override('server_ssl', True, 'RESTPROXY')
cfg.CONF.set_override('ssl_sticky', False, 'RESTPROXY')
self.httpsPatch = mock.patch(HTTPS, create=True,
new=fake_server.HTTPSHostValidation)
self.httpsPatch.start()
self._setUp()
# Set fake HTTPS connection's expectation
self.fake_certget_m.return_value = self.host_cert_val
# No CA certs for this test
self.getcacerts_m.return_value = []
# Pretend host cert exists
self.hcertpath_p = mock.patch(GETHOSTCERT,
return_value=(self.host_cert_path, True),
create=True).start()
super(TestSslHostCert, self).setUp()
def test_host_cert(self):
# SSL connection should be successful because of pre-configured cert
with self.network():
self.hcertpath_p.assert_has_calls([
mock.call(os.path.join(self.cert_base, 'host_certs'),
self.servername)
])
# sticky is disabled, no fetching allowed
self.assertFalse(self.sslgetcert_m.call_count)
# no ca certs, so host cert is only for this combined cert
self.certcomb_m.assert_has_calls([mock.call([self.host_cert_path],
self.comb_cert_path)])
class TestSslCaCert(test_ssl_certificate_base):
def setUp(self):
self.setup_config_files()
cfg.CONF.set_override('server_ssl', True, 'RESTPROXY')
cfg.CONF.set_override('ssl_sticky', False, 'RESTPROXY')
self.httpsPatch = mock.patch(HTTPS, create=True,
new=fake_server.HTTPSCAValidation)
self.httpsPatch.start()
self._setUp()
# pretend to have a few ca certs
self.getcacerts_m.return_value = ['ca1.pem', 'ca2.pem']
# Set fake HTTPS connection's expectation
self.fake_certget_m.return_value = 'DUMMYCERTIFICATEAUTHORITY'
super(TestSslCaCert, self).setUp()
def test_ca_cert(self):
# SSL connection should be successful because CA cert was present
# If not, attempting to create a network would raise an exception
with self.network():
# sticky is disabled, no fetching allowed
self.assertFalse(self.sslgetcert_m.call_count)
# 2 CAs and no host cert so combined should only contain both CAs
self.certcomb_m.assert_has_calls([mock.call(['ca1.pem', 'ca2.pem'],
self.comb_cert_path)])
class TestSslWrongHostCert(test_ssl_certificate_base):
def setUp(self):
self.setup_config_files()
cfg.CONF.set_override('server_ssl', True, 'RESTPROXY')
cfg.CONF.set_override('ssl_sticky', True, 'RESTPROXY')
self._setUp()
# Set fake HTTPS connection's expectation to something wrong
self.fake_certget_m.return_value = 'OTHERCERT'
# No CA certs for this test
self.getcacerts_m.return_value = []
# Pretend host cert exists
self.hcertpath_p = mock.patch(GETHOSTCERT,
return_value=(self.host_cert_path, True),
create=True).start()
super(TestSslWrongHostCert, self).setUp()
def test_error_no_cert(self):
# since there will already be a host cert, sticky should not take
# effect and there will be an error because the host cert's contents
# will be incorrect
tid = test_api_v2._uuid()
data = {}
data['network'] = {'tenant_id': tid, 'name': 'name',
'admin_state_up': True}
with mock.patch(HTTPS, new=fake_server.HTTPSHostValidation):
req = self.new_create_request('networks', data, 'json')
res = req.get_response(self.api)
self.assertEqual(res.status_int,
webob.exc.HTTPInternalServerError.code)
self.hcertpath_p.assert_has_calls([
mock.call(os.path.join(self.cert_base, 'host_certs'),
self.servername)
])
# sticky is enabled, but a host cert already exists so it shant fetch
self.assertFalse(self.sslgetcert_m.call_count)
# no ca certs, so host cert only for this combined cert
self.certcomb_m.assert_has_calls([mock.call([self.host_cert_path],
self.comb_cert_path)])
class TestSslNoValidation(test_ssl_certificate_base):
def setUp(self):
self.setup_config_files()
cfg.CONF.set_override('server_ssl', True, 'RESTPROXY')
cfg.CONF.set_override('ssl_sticky', False, 'RESTPROXY')
cfg.CONF.set_override('no_ssl_validation', True, 'RESTPROXY')
self._setUp()
super(TestSslNoValidation, self).setUp()
def test_validation_disabled(self):
# SSL connection should be successful without any certificates
# If not, attempting to create a network will raise an exception
with contextlib.nested(
mock.patch(HTTPS, new=fake_server.HTTPSNoValidation),
self.network()
):
# no sticky grabbing and no cert combining with no enforcement
self.assertFalse(self.sslgetcert_m.call_count)
self.assertFalse(self.certcomb_m.call_count)
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