In this installment of our "What did you do in Mitaka?" series, Ihar Hrachyshka talks about his work on Neutron both in Mitaka, and what’s planned for Newton.

You can listen below. If the player doesn’t work for you, you can listen HERE.

Rich: Hello, I’m speaking with Ihar Hrachyshka about the work that he did in the RDO community on the Mitaka release of OpenStack. Thank you for taking time to speak with me.

Ihar: Thank you for having me

R: Could you mention the things that you’ve worked on in Mitaka, both upstream, and also specifically for RDO.

I: One thing that I was focusing on during Mitaka in upstream is – we are looking at how we can enhance the upgrade story for the project I work on, which is Neutron.

(See Neutron Mitaka release notes )

There was a lot of good work done in this regard on other projects, in previous cycles, like in Nova. And Neutron was kind of lagging on that. During Mitaka, we formed a sub-team that looks specifically into the upgrade story, and we’ve identified several pain points that we were addressing during this cycle, and plan to continue the work in Neutron, and forward.

One thing that we’ve identified is even though so-called rolling upgrades were kind of supported in the sense that there was some code to handle that scenario, for upgrades. But it was never actually validated in our CI gate, so no-one could be sure that it actually worked. So that was one thing that we tackled. We added proper jobs to validate these scenarios, and make sure that they work.

Another thing for upgrades is that we are looking at reducing and maybe even eliminating any downtime for API endpoints for Neutron, especially in the case when you have highly-available controllers. That involves a lot of work in the code base, a lot of change there to refactor the code. We’ve already started the work during Mitaka, and we’re going to proceed with that in Newton. We hope that we complete this work in Newton, and then for all upgrades starting from Newton to the next release, operators will be able to retain their Neutron API available while controllers are upgraded one by one. That’s one thing that I was working on.

There are other things. There was a lot of work done in Neutron in the scope of Quality of Service (QOS). The initial support for QOS in Neutron was merged in Liberty, but it’s still quite limited, so we expand on what we had done in that release. Specifically, the initial support was just for OpenVSwitch, but in Mitaka we added support for Linuxbridge ml2 driver. We also added role-based access control for QOS policies. We added support for so-called DSCP tags, which is a feature to prioritize traffic based on which port it came from.

Another interesting thing that we finally tackled in Mitaka is MTU support. This is one of the huge pain points that were identified by operators in the past, that Neutron, while being the networking solution for OpenStack, cannot actually properly handle MTUs – which stands for Maximum Transfer Unit. Neutron could not actually handle, neither standard MTUs for ethernet, nor so-called jumbo frames, which is really bad. It means that instances did not have access to the full capabilities of the underlying physical infrastructure. That should hopefully go away in Mitaka, because there were several changes there, both on the Neutron side, and on Nova, which now should make Neutron work out of the box, both for non-standard and standard MTU sizes.

Finally, one thing to note, apart from pure upstream work in the Master branch, is that in Neutron, in this Mitaka release, we adopted a new approach to handle backports for stable branches. Now instead of waiting for something to break in a user installation, and then reacting to their bug reports, we are proactively backporting all of the bug fixes from the latest master branch into stable branches, and release new stable releases, often. We hope that it will reduce the number of painful problems, in actual installations that rely on stable branches, very significantly.

R: This sounds like an enormous amount of work. How many people are you working with across how many organizations, would you estimate?

I: In OpenStack it’s always that you work with other people. I would say … I don’t know … there are I think 5, 6, major contributors to Neutron. Surely, nothing comes in OpenStack if you’re just single. So that’s collaboration.

R: Thank you very much for your time, and we look forward to seeing what comes in Newton.

I: Thank you.