[ovs-dev] [PATCH 0/3] OVN: add Controller Events

Ben Pfaff blp at ovn.org
Fri Jul 5 22:05:30 UTC 2019


On Fri, Jun 14, 2019 at 05:53:20PM +0200, Lorenzo Bianconi wrote:
> The series here introduces a new table, Controller_Event, for this
> purpose. Traffic into OVS can raise a controller() event that results in
> a Controller_Event being written to the southbound database. The
> intention is for a CMS to see the events and take some sort of action.
> The "handled" column of the event is initially set to "false" by OVN.
> When the CMS has seen the event and taken appropriate action, then the
> CMS sets this field to "true'. When ovn-controller sees that the event
> has been handled, it deletes the event from the database.
> 
> Controller events are only added to the southbound database if they have
> been enabled in the nb_global table via the options:controller_event
> setting.

The above paragraphs of high-level information are helpful, but they are
only in email and do not appear in the documentation.  I suggest adding
them to the documentation so that the reader can see the whole picture.

Some other high-level design comments:

- I don't see an explanation of the sequence number and how it's used in
  practice.

- I don't yet understand why it's better to have the CMS set 'handled'
  and then have ovn-controller delete the row, than to have the CMS
  delete the row directly.

- The passive voice in the second paragraph above makes it ambiguous who
  sets options:controller_event.  I think that the CMS sets this; it
  would be best for the documentation to say so.

Thanks,

Ben.


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