Add a StaticScheduler without automatic scheduling

The automatic scheduling that was introduced in [0] is having some
issues. Add a StaticScheduler that can be used as an alternative for
deployments that want explicit control over where their BGP speakers are
getting scheduled.

Add a job that runs with the new scheduler.

[0] https://review.opendev.org/c/openstack/neutron-dynamic-routing/+/478455

Depends-On: https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/815294
Closes-Bug: 1920065
Signed-off-by: Dr. Jens Harbott <harbott@osism.tech>
Change-Id: Ib7fcd0c7371bc75089b10024ee1b6e75c98f0188

.zuul.yaml

@@ -1,3 +1,15 @@
+- job:
+    name: neutron-dynamic-routing-static
+    parent: neutron-tempest-plugin-dynamic-routing
+    vars:
+      devstack_localrc:
+        BGP_SCHEDULER_DRIVER: neutron_dynamic_routing.services.bgp.scheduler.bgp_dragent_scheduler.StaticScheduler
+      devstack_local_conf:
+        test-config:
+          $TEMPEST_CONFIG:
+             neutron_plugin_options:
+               bgp_schedule_speakers_to_agents: true
+
 - job:
     name: neutron-dynamic-routing-functional
     parent: neutron-functional
@@ -22,6 +34,7 @@
     check:
       jobs:
         - neutron-dynamic-routing-functional
+        - neutron-dynamic-routing-static
         - neutron-tempest-plugin-dynamic-routing
     gate:
       jobs:

doc/source/admin/agent-scheduler.rst

@@ -48,8 +48,24 @@ BGP Scheduler
 BGP Speaker and DRAgent has 1:N association which means one BGP speaker can be
 scheduled on multiple DRAgents.
 
+There are different options for the scheduling algorithm to be used, these can
+be selected via the ``bgp_drscheduler_driver`` configuration option.
+
+StaticScheduler
+~~~~~~~~~~~~~~~
+
+This is the most simple option, which does no automatic scheduling at all.
+Instead it relies on API requests to explicitly associate BGP speaker with
+DRAgents and to disassociate them again.
+
+Sample configuration::
+
+    bgp_drscheduler_driver = neutron_dynamic_routing.services.bgp.scheduler.bgp_dragent_scheduler.StaticScheduler
+
 Here is an example to associate/disassociate a BGP Speaker to/from a DRAgent.
 
+.. TODO(frickler): update the examples to use OSC
+
 ::
 
   (neutron) bgp-speaker-list
@@ -88,7 +104,22 @@ Here is an example to associate/disassociate a BGP Speaker to/from a DRAgent.
 
   (neutron)
 
-.. note:: Currently, auto-scheduling is not supported.
+ReST API's for neutron-dynamic-routing scheduler are defined as part of the
+`Neutron API reference`_.
+
+.. _Neutron API reference: https://docs.openstack.org/api-ref/network/#bgp-dynamic-routing
+
+ChanceScheduler
+~~~~~~~~~~~~~~~
+
+This is the default option. It will automatically schedule newly created BGP
+speakers to one of the active DRAgents. When a DRAgent goes down, the BGP
+speaker will be disassociated from it and an attempt is made to schedule
+it to a different agent. Note that this action will override any manual
+associations that have been performed via the API, so you will want to use
+this scheduler only in very basic deployments.
+
+Sample configuration::
+
+    bgp_drscheduler_driver = neutron_dynamic_routing.services.bgp.scheduler.bgp_dragent_scheduler.ChanceScheduler
 
-ReST API's for neutron-dynamic-routing scheduler is defined in the
-API document :doc:`/reference/index`

doc/source/admin/system-design.rst

@@ -127,4 +127,4 @@ It manages and configures different dynamic routing stack through
 
 .. note::
  Currently, only integration with `os-ken <https://docs.openstack.org/os-ken/latest/>`_
- is supported. Future releases will add the support for Quagga, Bird, etc.
+ is supported.

doc/source/contributor/dragent-drivers.rst

@@ -53,9 +53,8 @@ functionality of a dynamic routing protocol::
                 +-------------------------------+
 
 .. note::
- In the first release, only the integration with os-ken is supported. Later release will
- have support for Quagga, Bird etc. Besides, BGP is the only protocol supported now
- but support for more dynamic routing protocols might come in the future.
+ Currently only the integration with os-ken is supported
+ BGP is the only protocol supported.
 
 
 Configuration

doc/source/contributor/testing.rst

@@ -565,7 +565,8 @@ Service Test
 
     * Schedule the BGP speaker to ``BGP dynamic routing agent``
 
-    The first BGP speaker is scheduled to the first dynamic routing agent automatically.
+    With the default scheduler configuration, the first BGP speaker is
+    scheduled to the first dynamic routing agent automatically.
     So for a simple setup, there is nothing to be done here.
 
     * Verify scheduling of the BGP speaker to the agent.

neutron_dynamic_routing/services/bgp/scheduler/bgp_dragent_scheduler.py

@@ -218,3 +218,9 @@ class WeightScheduler(base_scheduler.BaseWeightScheduler,
     def __init__(self):
         super(WeightScheduler, self).__init__(self)
         self._register_callbacks()
+
+
+class StaticScheduler(BgpDrAgentFilter):
+
+    def __init__(self):
+        super(StaticScheduler, self).__init__()

releasenotes/notes/add-static-scheduler-a3b0f54b964ae306.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    A new BGP scheduler has been added, called ``StaticScheduler``. It will
+    not perform any automatic scheduling of speakers to agents, instead
+    relying on API calls to perform explicit scheduling, fulfilling the
+    needs of larger deployments.
+    See also bug `1920065 <https://bugs.launchpad.net/neutron/+bug/1920065>`_.
+    The plan is to make the ``StaticScheduler`` the default option for the next
+    release and possibly deprecate the current default, ``ChanceScheduler``.