[openstack-dev] [tripleo][python3] python3 readiness?

Tom Barron tpb at dyncloud.net
Wed Feb 14 21:53:22 UTC 2018


On 13/02/18 16:53 -0600, Ben Nemec wrote:
>
>
>On 02/13/2018 01:57 PM, Tom Barron wrote:
>>Since python 2.7 will not be maintained past 2020 [1] it is a 
>>reasonable conjecture that downstream distributions
>>will drop support for python 2 between now and then, perhaps as 
>>early as next year.
>
>I'm not sure I agree.  I suspect python 2 support will not go quietly 
>into that good night.  Personally I anticipate a lot of kicking and 
>screaming right up to the end, especially from change averse 
>enterprise users.
>
>But that's neither here nor there.  I think we're all in agreement 
>that python 3 support is needed. :-)

Yeah, but you raise a good issue.  How likely is it that EL8 will 
choose -- perhaps under duress -- to support both python 2 and python 
3 in the next big downstream release.  If this is done long enough 
that we can support TripleO deployments on CentOS 8 using python2 
while at the same time testing TripleO deployments on CentOS using 
python3 then TripleO support for Fedora wouldn't be necessary.

Perhaps this question is settled, perhaps it is open.  Let's try to 
nail down which for the record.

>
>>In Pike, OpenStack projects, including TripleO, added python 3 unit 
>>tests.  That effort was a good start, but likely we can agree that 
>>it is *only* a start to gaining confidence that real life TripleO 
>>deployments will "just work" running python 3.  As agreed in the 
>>TripleO community meeting, this email is intended to kick off a 
>>discussion in advance of PTG on what else needs to be done.
>>
>>In this regard it is worth observing that TripleO currently only 
>>supports CentOS deployments and CentOS won't have python 3 support 
>>until RHEL does, which may be too late to test deploying with 
>>python3 before support for python2 is dropped.  Fedora does have 
>>support for python 3 and for this reason RDO has decided [2] to 
>>begin work to run with *stabilized* Fedora repositories in the Rocky 
>>cycle, aiming to be ready on time to migrate to Python 3 and support 
>>its use in downstream and upstream CI pipelines.
>
>So that means we'll never have Python 3 on CentOS 7 and we need to 
>start supporting Fedora again in order to do functional testing on 
>py3? That's potentially messy.  My recollection of running TripleO CI 
>on Fedora is that it was, to put it nicely, a maintenance headache.  
>Even with the "stabilized" repos from RDO, TripleO has a knack for 
>hitting edge case bugs in a fast-moving distro like Fedora.  I guess 
>it's not entirely clear to me what the exact plan is since there's 
>some discussion of frozen snapshots and such, which might address the 
>fast-moving part.
>
>It also means more CI jobs, unless we're okay with dropping CentOS 
>support for some scenarios and switching them to Fedora.  Given the 
>amount of changes between CentOS 7 and current Fedora that's a pretty 
>big gap in our testing.
>
>I guess if RDO has chosen this path then we don't have much choice.  
>As far as next steps, the first thing that would need to be done is to 
>get TripleO running on Fedora again.  I suggest starting with https://github.com/openstack/instack-undercloud/blob/3e702f3bdfea21c69dc8184e690f26e142a13bff/instack_undercloud/undercloud.py#L1377 
>:-)
>
>-Ben
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