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Should we target it for Kilo? It does not seem right to allow it
slipping into the next release while we know there are operators
relying on the feature.

On 03/11/2015 08:42 PM, Assaf Muller wrote:
> I've filed a bug here: 
> https://bugs.launchpad.net/neutron/+bug/1430984
> 
> I've outlined the path I'd like to take in the bug description.
> 
> ----- Original Message -----
>> +1 on avoiding changes that break rolling upgrade.
>> 
>> Rolling upgrade has been working so far (at least from my
>> perspective), and as openstack adoption spreads, it will be
>> important for more and more users.
>> 
>> How do we make rolling upgrade a "supported" part of Neutron?
> 
> Finding a sane way to test it would be a start. I'm still
> looking...
> 
>> 
>> - Jack
>> 
>>> -----Original Message----- From: Assaf Muller
>>> [mailto:amuller at redhat.com] Sent: Thursday, March 05, 2015
>>> 11:59 AM To: OpenStack Development Mailing List (not for usage
>>> questions) Subject: Re: [openstack-dev] [Neutron] Issue when
>>> upgrading from Juno to Kilo due to agent report_state RPC
>>> namespace patch
>>> 
>>> 
>>> 
>>> ----- Original Message -----
>>>> To turn this stuff off, you don't need to revert.  I'd
>>>> suggest just setting the namespace contants to None, and that
>>>> will result in the same thing.
>>>> 
>>>> 
>>> http://git.openstack.org/cgit/openstack/neutron/tree/neutron/common/constants.py#
>>>
>>> 
n152
>>>> 
>>>> It's definitely a non-backwards compatible change.  That was
>>>> a conscious choice as the interfaces are a bit of a tangled
>>>> mess, IMO.  The non-backwards compatible changes were simpler
>>>> so I went that route, because as far as I could tell, rolling
>>>> upgrades were not supported.  If they do work, it's due to
>>>> luck.  There's multiple things including the lack of testing
>>>> this scenario to lack of data versioning that make it a 
>>>> pretty shaky area.
>>>> 
>>>> However, if it worked for some people, I totally get the
>>>> argument against breaking it intentionally.  As mentioned
>>>> before, a quick fix if needed is to just set the namespace
>>>> constants to None.  If someone wants to do something to make
>>>> it backwards compatible, that's even better.
>>>> 
>>> 
>>> I sent out an email to the operators list to get some
>>> feedback: 
>>> http://lists.openstack.org/pipermail/openstack-operators/2015-March/006429.html
>>>
>>>
>>> 
And at least one operator reported that he performed a rolling Neutron
>>> upgrade from I to J successfully. So, I'm agreeing with you
>>> agreeing with me that we probably don't want to mess this up
>>> knowingly, even though there is no testing to make sure that it
>>> keeps working.
>>> 
>>> I'll follow up on IRC with you to figure out who's doing what.
>>> 
>>>> -- Russell Bryant
>>>> 
>>>> On 03/04/2015 11:50 AM, Salvatore Orlando wrote:
>>>>> To put in another way I think we might say that change
>>>>> 154670 broke backward compatibility on the RPC interface. 
>>>>> To be fair this probably happened because RPC interfaces
>>>>> were organised in a way such that this kind of breakage was
>>>>> unavoidable.
>>>>> 
>>>>> I think the strategy proposed by Assaf is a viable one. The
>>>>> point about being able to do rolling upgrades only from
>>>>> version N to N+1 is a sensible one, but it has more to do
>>>>> with general backward compability rules for RPC
>>>>> interfaces.
>>>>> 
>>>>> In the meanwhile this is breaking a typical upgrade
>>>>> scenario. If a fix allowing agent state updates both
>>>>> namespaced and not is available today or tomorrow, that's
>>>>> fine. Otherwise I'd revert just to be safe.
>>>>> 
>>>>> By the way, we were supposed to have already removed all
>>>>> server rpc callbacks in the appropriate package... did we
>>>>> forget out this one or is there a reason for which it's
>>>>> still in neutron.db?
>>>>> 
>>>>> Salvatore
>>>>> 
>>>>> On 4 March 2015 at 17:23, Miguel Ángel Ajo
>>>>> <majopela at redhat.com <mailto:majopela at redhat.com>> wrote:
>>>>> 
>>>>> I agree with Assaf, this is an issue across updates, and we
>>>>> may want (if that’s technically possible) to provide access
>>>>> to those functions with/without namespace.
>>>>> 
>>>>> Or otherwise think about reverting for now until we find a 
>>>>> migration strategy
>>>>> 
>>>>> 
>>> https://review.openstack.org/#/q/status:merged+project:openstack/neutron+branch:m
>>>
>>> 
aster+topic:bp/rpc-docs-and-namespaces,n,z
>>>>> 
>>>>> 
>>>>> Best regards, Miguel Ángel Ajo
>>>>> 
>>>>> On Wednesday, 4 de March de 2015 at 17:00, Assaf Muller
>>>>> wrote:
>>>>> 
>>>>>> Hello everyone,
>>>>>> 
>>>>>> I'd like to highlight an issue with: 
>>>>>> https://review.openstack.org/#/c/154670/
>>>>>> 
>>>>>> According to my understanding, most deployments upgrade
>>>>>> the controllers first and compute/network nodes later.
>>>>>> During that time period, all agents will fail to report
>>>>>> state as they're sending the report_state message 
>>>>>> outside of any namespace while the server is expecting
>>>>>> that message in a namespace. This is a show stopper as
>>>>>> the Neutron server will think all of its agents are
>>>>>> dead.
>>>>>> 
>>>>>> I think the obvious solution is to modify the Neutron
>>>>>> server code so that it accepts the report_state method
>>>>>> both in and outside of the report_state RPC namespace and
>>>>>> chuck that code away in L (Assuming we support rolling
>>>>>> upgrades only from version N to N+1, which while is
>>>>>> unfortunate, is the behavior I've seen in multiple places
>>>>>> in the code).
>>>>>> 
>>>>>> Finally, are there additional similar issues for other
>>>>>> RPC methods placed in a namespace this cycle?
>>>>>> 
>>>>>> 
>>>>>> Assaf Muller, Cloud Networking Engineer Red Hat
>>>>>> 
>> 
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>>
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