OVN octavia provider driver should spawn long-living process in driver agent

[Maciej Jozefczyk]

The OVN Octavia provider driver in OvnProviderHelper caches attributes [1]:

ovn_nbdb_api_for_events = None
ovn_nb_idl_for_events = None
ovn_nbdb_api = None

to not re-create each time OVN IDL that is used for handling events.

Now we are able to use Octavia Driver Agent [2] instead to not have those long-living IDLs in API process.

TODO:
- create driver agent and register its entry point
- While setting up the driver agent instance start IDL that will handle events:
https://opendev.org/openstack/ovn-octavia-provider/src/branch/master/ovn_octavia_provider/driver.py#L279
- stop caching ovn_nbdb_api, ovn_nb_idl_for_events and ovn_nbdb_api_for_events in the OvnProviderHelper.

[1] https://opendev.org/openstack/ovn-octavia-provider/src/branch/master/ovn_octavia_provider/driver.py#L273
[2] https://docs.openstack.org/octavia/latest/contributor/guides/providers.html#provider-agent-method-invocation

[Lajos Katona (lajos-katona)]

Isn't this more an RFE?

[Maciej Jozefczyk (maciejjozefczyk)]

This will not change anything from user perspective. I could say that it is a bug, cause we shouldn't have long living process running in Octavia WSGI application.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/718203

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/718203
Committed: https://git.openstack.org/cgit/openstack/ovn-octavia-provider/commit/?id=c6cee9207349a12e499cbc81fe0e5d4d5bfa015c
Submitter: Zuul
Branch: master

commit c6cee9207349a12e499cbc81fe0e5d4d5bfa015c
Author: Brian Haley <email address hidden>
Date: Tue Apr 7 15:54:57 2020 -0400

    Spawn long-running processes in the driver agent

    The OVN Octavia provider driver in the OvnProviderHelper
    class caches these attributes:

        ovn_nbdb_api_for_events
        ovn_nb_idl_for_events
        ovn_nbdb_api

    to not re-create things each time OVN IDL that is used for
    handling events is called.

    We should be using the Octavia Driver Provider Agent framework
    instead to not have those long-running IDLs in the API process.

    This change:
    - Creates driver provider agent and registers its entry point
    - While setting up the driver agent instance, start IDL that
      will handle events
    - Stop caching ovn_nbdb_api, ovn_nb_idl_for_events and
      ovn_nbdb_api_for_events in the OvnProviderHelper class

    Change-Id: I0034a48997bd6b95e1b51bfcbd56e8372b35e62f
    Closes-bug: #1871355

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/ussuri
Review: https://review.opendev.org/722796

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/722796
Committed: https://git.openstack.org/cgit/openstack/ovn-octavia-provider/commit/?id=8abe519c65234db5cf6df1dbaaf9457a0f5e905a
Submitter: Zuul
Branch: stable/ussuri

commit 8abe519c65234db5cf6df1dbaaf9457a0f5e905a
Author: Brian Haley <email address hidden>
Date: Tue Apr 7 15:54:57 2020 -0400

    Spawn long-running processes in the driver agent

    The OVN Octavia provider driver in the OvnProviderHelper
    class caches these attributes:

        ovn_nbdb_api_for_events
        ovn_nb_idl_for_events
        ovn_nbdb_api

    to not re-create things each time OVN IDL that is used for
    handling events is called.

    We should be using the Octavia Driver Provider Agent framework
    instead to not have those long-running IDLs in the API process.

    This change:
    - Creates driver provider agent and registers its entry point
    - While setting up the driver agent instance, start IDL that
      will handle events
    - Stop caching ovn_nbdb_api, ovn_nb_idl_for_events and
      ovn_nbdb_api_for_events in the OvnProviderHelper class

    Conflicts:
       ovn_octavia_provider/tests/functional/test_driver.py

    Change-Id: I0034a48997bd6b95e1b51bfcbd56e8372b35e62f
    Closes-bug: #1871355
    (cherry picked from commit c6cee9207349a12e499cbc81fe0e5d4d5bfa015c)