[neutron] April 2021 - PTG Summary

Slawek Kaplonski skaplons at redhat.com
Mon Apr 26 14:44:51 UTC 2021


Below is my summary of the Neutron sessions during the PTG last week.
Etherpad with agenda and all notes from the sessions is available at https://

If You want to discuss some topic in more details, please start new thread for it to 
keep this one clean.

## Day 1 (Monday) 

### Retrospective of the Wallaby cycle 
Good things: 
* we accomplished our community goals this cycle, like e.g. rootwrap to 
 privsep migration, 
* migration to the secure RBAC, 
* many performance improvements, 
* CI improvements and the job simplification/reducing, 
* stable team, and a lot of small patches from all around the world, 
* OVN feature gap with OVS is shrinking, 
* team support to implement address groups, including RBAC support. 

In the list of not so good things we mentioned: 
* During the previous PTG we were talking about some OVN related 
 guides/sessions but we didn't made any, 
* networking-midonet - (yet another) stadium project deprecated due to lack of 
 maintainers, but it's better to have them clearly marked as out of stadium, 
 than false expectations - we can bring such projects back when needed anyway, 
* still unstable CI, mainly tempest and tempest-plugin jobs, also during this 
 release functional tests. 

As for action items for the _Xena_ cycle, we listed couple of things: 
* Miguel wants to do the ovn knowledge share internally in his company and 
 later share the material, 
* we will keep working on the improvements for our CI, list of all opened, CI 
 related bugs can be found at 
 https://tinyurl.com/neutron-gate-failures and we will work on 
 reducing that list in next months. 
* Rodolfo and Miguel will follow up on Nova's plans to drop eventlet and move to 
 the threading and will investigate if we can try to do something similar in 
 the Neutron, 
* Akihiro raised good point about ML2/OVN and stadium projects. We should 
 clarify the support plan for OVN in all of our stadium projects. Lajos and 
 Lucas volunteered to work on that. 

### Secure RBAC - testing - discussion with QA team 
As next session in the first day, we attended QA team's session about testing 
new secure RBAC policies. Summary of that discussion can be found in the 
etherpad: https://etherpad.opendev.org/p/qa-xena-ptg. QA team wants to switch 
each project to enforce new defaults and the system scope tokens in the 
Devstack. We will have to monitor that and check what needs to be fixed on our 
side to accomplish that. 

### Deprecated hybrid plug and the iptables_hybrid firewall driver 
Bence proposed discussion about potential deprecation of the iptables_hybrid 
firewall driver as we have now native openvswitch driver too. After discussion 
we decided that we are not going to deprecate it, at least for now. There are 
known differences between those two drivers and there is still many usecases 
where people wants to use iptables_hybrid driver. 

### Future of the Linuxbridge backend 
As the last topic of the first day we discussed future of the Linuxbridge 
backend and ML2 driver. The same topic was discussed in the http://kaplonski.pl/
blog/shanghai_ptg_summary/ and then, based on the 
feedback from operators we decided that we are not going to deprecate this 
backend anytime soon as many people are still using it. 
But now we are couple of cycle later and things didn't change a lot. We still 
don't have anyone who would like to maintain it. In most cases it works fine but 
there are also pretty many bugs reported for that backend, which don't have 
owners - see https://tinyurl.com/linuxbridge-bugs. But things may 
change in the future and e.g. removal of the legacy iptables from the main 
distributions may makes things harder to work. 
We again had feedback, e.g. from Jon that NASA is using that driver and want's 
to keep using it. But from the other hand in the core Neutron we don't have 
anyone interested in maintaining it currently. 
The outcome of the discussion is that we will again raise that topic and ask 
operators about: 
- who is using it and what are the use cases addressed by that driver - maybe we 
 can help with proposing another solution, 
- who is willing to help with maintenance of that backend. 
If You are using Linuxbridge backend, please give us such feedback. 

For Xena status is that we still do our best to keep Linuxbridge backend to be 
running and fully supported but we will also revisit its status again in the 
next PTG. 

## Day 2 (Tuesday) 

### Continuation of "L3 feature improvements" 
During the second day of the PTG we had very interesting discussions about L3 
improvements. We discussed bunch of the RFEs proposed by Bence, Lajos and Manu: 
* [RFE] Add BFD support for Neutron https://bugs.launchpad.net/neutron/+bug/
 and the spec: https://review.opendev.org/c/openstack/neutron-specs/+/767337
* [RFE] Allow explicit management of default routes: https://bugs.launchpad.net/
 and the spec: https://review.opendev.org/c/openstack/neutron-specs/+/781475
* Allow multiple external gateways on a router: https://bugs.launchpad.net/neutron/
 and the spec: https://review.opendev.org/c/openstack/neutron-specs/+/779511
* [RFE] Enhancement to Neutron BGPaaS to directly support Neutron Routers & 
 bgp-peering from such routers over internal & external Neutron Networks https://
 and the spec: https://review.opendev.org/c/openstack/neutron-specs/+/783791
* [RFE] BFD for BGP Dynamic Routing: https://bugs.launchpad.net/neutron/+bug/
 and the spec: https://review.opendev.org/c/openstack/neutron-specs/+/785349.
 That one still needs to be discussed and approved during the drivers meeting. 

General outcome from the discussion is that during the Xena cycle we at least 
wants to have all those specs merged to have agreement about implementation 
details. When that will be done, Bence, Lajos and others from Ericsson will work 
on the implementation of those RFEs. 

### Tap-as-a-service (taas) project 
Next topic which we discussed during Tuesday's session was about 
Tap-as-a-service: https://opendev.org/x/tap-as-a-service project. Few cycle 
back we were thinking about including it in the Neutron stadium but finally that 
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