Neutron/Full-Stack White-Box Tests Framework

Launchpad blueprint:

This blueprint specifies the framework needed to write new full-stack tests targeting Neutron components (as opposed to tests which validate integration among different OpenStack components). These tests are intended to be white-box - they will validate Neutron’s functionality, mainly on the operating system level.

In other words, full-stack tests intend to test Neutron on its own, without any other OpenStack components, and fall between functional and Tempest tests.

Problem Description

Currently there are 3 main types of tests for Neutron:

  1. Unit tests, which intend to check the code mostly at the function level where each function is tested separately. For example: make sure that function X returns value Y when the arguments are A, B and C.
  2. Functional tests, which target only single sub-components and intend to validate interaction with external (system or host-local) resources (mostly operating system interactions and outside packages like Open-vSwitch and iproute2...) An example functional test could look like:
def test_router_lifecycle(self):
    """Create a router and check that the agent creates various resources.

    self.agent is an instance of type L3NATAgent (the main class in the L3
    Agent) and is created as part of the test. The assertions make sure that
    various OS resources (like interfaces, namespaces, processes) are created
    as part of the creation of a new router.
    """
    router_info = self.generate_router_info(enable_ha)
    router = self.manage_router(self.agent, router_info)

    self.assertTrue(self._namespace_exists(router))
    self.assertTrue(self._metadata_proxy_exists(self.agent.conf, router))
    self._assert_internal_devices(router)
    self._assert_external_device(router)
    self._assert_gateway(router)
    self._assert_floating_ips(router)
    self._assert_snat_chains(router)
    self._assert_floating_ip_chains(router)

    self._delete_router(self.agent, router.router_id)
    self._assert_router_does_not_exist(router)
  1. Tempest tests, which check that OpenStack as a whole and Neutron in particular behave as intended. Tempest tests are split to 2 groups:
    1. Scenario tests (start a new instance and make sure that the instance has connectivity to the external network). These tests often intend to check more than one component at a time (as opposed to full-stack tests discussed here, which check only Neutron).
    2. API tests (create a new router, make sure that the controller is aware of it and delete it).

There is currently no way to check Neutron as a standalone project and the interaction between the different Neutron components without other OpenStack components such as Nova or Cinder.

Proposed Change

The framework will be written in the Neutron tree, thus allowing for easier writing of new tests (as opposed to out-of-tree Tempest tests), being aware of Neutron resources used during tests (executing Neutron agents and cleaning up used resources), and running specific Neutron tests intended to check the interaction between the different Neutron components.

The framework intends to achieve state isolation, achieved through reseting the state of Neutron components and restarting Neutron agents when needed (Tempest currently does this manually - routers created during tests needs to be explicitly deleted afterwards).

Currently the intention is to reset said state after each full-stack test, but this can be easily changed (we might want to do so after each test suite instead) once enough tests are added to the framework which will allow reliable benchmarking.

The framework will support:

  1. Writing full-stack tests using the unittest module,
  2. Restarting all the Neutron processes which are needed (neutron-server, L3 agent, etc...) using setUp and cleanUp when appropriate,
  3. Wiping the databases and cleaning up resources (specifically running neutron-ovs-cleanup and neutron-netns-cleanup),
  4. Using only python-neutronclient to communicate with Neutron.
def test_ha_router_startup(self):
    """Create an HA router for two agents and make sure they can communicate.

    While this full-stack test look similar to 'test_router_lifecycle', it
    relies on the Neutron API (python-neutronclient) to create a new router
    and actual processes (one neutron-server, 2 pairs of L3 and OVS agents),
    meaning that once a request is made, it goes through all relevant agents
    and components (instead of a single sub-component). OS resources are also
    checked in this test.
    """
  def test_ha_router_startup(self):
      l3_agents = ['neutron-l3-1-agent', 'neutron-l3-2-agent']

      router = self.client.create_router(
          body={'router': {'name': 'router-test',
                           'tenant_id': uuidutils.generate_uuid(),
                           'ha': True}})
      router_id = router['router']['id']

      self._assert_namespaces_exists(router_id, l3_agents)
      master, slave = self._get_master_and_slave(router_id, l3_agents)

      # Only if the two agents can ping each other will the other router
      # change itself to be the backup router.
      test_daemon.wait_until(
          lambda: 'backup' in self._get_ha_state(router_id, slave))

Running full-stack tests will require one to setup devstack and stop all the services (‘./stack.sh’, ‘./unstack.sh’), then using tox to run the tests. Further steps might be needed down the line to setup databases and other resources, but an attempt to minimize the steps required to run the tests will be taken over time.

Data Model Impact

None

REST API Impact

None

Security Impact

None

Notifications Impact

None

Other End User Impact

Users will be able to manually execute full-stack tests using normal tools (such as tox), though admins and cloud users don’t need to run these tests after deployment.

No changes to python-neutronclient are needed.

Performance Impact

None

IPv6 Impact

None

Other Deployer Impact

None

Developer Impact

Writing new features might require writing full-stack tests for them, as well as unit and function tests.

Community Impact

Running full-stack tests will be available to run, similarly to current unit and functional tests, and will increase the level of credibility and reliability of new and existing Neutron features (both upstream and downstream).

Alternatives

Writing these kind of tests could be done in Tempest, however this approach was not chosen for several reasons:

  1. The direction of the QA effort in OpenStack precludes performing these kind of tests in Tempest since it is refocusing on multi-service testing.
  2. Full-stack tests allow for greater flexibility when developers write new Neutron code. Tempest policy dictates that only API tests are used with the various components, thus disallowing checks which involve system interaction and limiting tests of some of the features mentioned previously. Since the tests will be placed in-tree, the policy regarding new tests will be easier to determine.
  3. With this new type of testing we could test specific conditions (like consistency and sustained connectivity across agent restarts), which is impossible at this moment with Tempest.

Implementation

Assignee(s)

Primary assignee:

  1. John Schwarz <jschwarz@redhat.com>

Other contributors:

  1. Assaf Muller <amuller@redhat.com>
  2. Maru Newby <marun@redhat.com>

Work Items

  1. Add ability to manage daemonized Neutron processes,
  2. Implement supporting full-stack white-box testing framework,
  3. Add an example of a full-stack test.

Testing

The ultimate goal is having these new kinds of full-stack tests be run as part of the gate - coders will have to verify that their code passes specific ‘full-stack white-box tests’ gate job in order to get their patches merged.

Furthermore, changes to the infra project will be required to add these kind of tests to the gate (first as a non-voting and later as a voting gate job).

Tempest Tests

None

Functional Tests

None

API Tests

None

Documentation Impact

User Documentation

None

Developer Documentation

The following wiki page contains documentations and “best practices” regarding in-tree tests and full-stack tests specifically. Before writing new tests, a developer should read the following wiki page: https://wiki.openstack.org/wiki/Neutron/InTreeTests

TESTING.rst should be updated to reflect the new tests framework.

References

None