Dublin PTG Recap

We recently held the OpenStack PTG for the Rocky cycle. The PTG ran from Monday to Friday, February 26 – March 2, in Dublin, Ireland. So of course the big stuff to write about would be the interesting meetings between the teams, and the discussions about future development, right? Wrong! The big news from the PTG: Snow! So much so that Jonathan Bryce created the hashtag #SnowpenStack to commemorate the event!

Yes, Ireland was gripped by a record cold snap and about 5 inches/12 cm. of snow. Sure, I know that those of you who live in places where everyone owns a snow shovel just read that and snickered, but if you don’t have the equipment and experience to deal with it, it is a very big deal. They were also forecasting over twice that, and seeing how hard it was for them to deal with what they got, I’m glad it was only that much.

Ireland newspaper headline
The warnings posted ahead of the big storm

Since the storm was considered an emergency situation, and people were told to go home and stay there, that meant that there was no staff available for the conference, and it had to be shut down early. The people who ran the venue, Croke Park, Ireland’s biggest sports stadium, were wonderful and did everything they could to accommodate us.

Wait, what? A tech conference in a stadium?  Turns out they also have conference facilities on the upper floors of the stadium, so it wasn’t so odd after all. There is a hotel across the street from the entrance to the stadium, but it was completely booked on the Friday/Saturday I would be arriving, due to an important Rugby match between Ireland and Wales at Croke Park on Saturday. So I ended up at a hotel about a mile walk from the stadium. Which was fine at first, but turned out to be a bit of a problem once it got cold and the snows came, as it made the walk to Croke Park fairly difficult. But enough about snow – on to the PTG!

On Monday the API-SIG had a room for a full day’s discussion. However, it was remotely located at one end of the stadium, and for a while it was just the cores who showed up. We were afraid that we would end up only talking amongst ourselves, but fortunately people began showing up shortly thereafter, and by the afternoon we had a pretty good crowd.

Probably the most contentious issue we discussed was how to create guidelines for “action” APIs. These are the API calls that are made to make something happen, such as rebooting a server. We already recommend using the RESTful approach, which is to POST to the resource, with the desired action in the body of the request. However, many people resist doing that for various reasons, and decry the recommended approach as being too “purist” for their tastes. As one of the goals for the API-SIG is to make OpenStack APIs more consistent, we decided to take a two-pronged approach: recommend the RESTful approach for all new APIs, and a more RPC-like approach for existing APIs. We will survey the OpenStack codebase to get some numbers as to the different ways this is being done now, and if there is an approach that is more common than others, we will recommend that existing APIs use that format.

We also discussed the version discovery documents that have been stalled in review for some time. The problem with them is that they are incredibly detailed, making your brain explode before you can get all the way through. I volunteered to write a quick summary document that will be easier for most people to digest, and have it link to the more detailed parts of the full document.

Tuesday was another cross-project day. I started the day checking out the Kubernetes SIG, and was very impressed at the amount of interest. The room was packed, and after a round of introductions, they started to divide up what they planned to work on that day. Since I had other sessions to go to, I left before the work started, and moved to the room for the Cyborg project. This project aims to provide management of various acceleration resources, such as FPGAs, GPUs, and the like. I have an interest in this both because of my work with the Placement service, and also because my employer sells hardware with these sorts of accelerators, and would like to have a good solution in place. The Cyborg folks had some questions about how things would be handled in Placement, and I did my best to answer them. However, I wasn’t sure how much the rest of the Nova team would want to alter the existing VM creation flow to accommodate Cyborg, so we brainstormed for a while and came up with an approach that involved the Cyborg agent monitoring notifications from Nova to detect when it needed to act. This would mean a lot more work for Cyborg, and would sometimes mean that a new VM that requested an accelerator may not have the accelerator available right away, but it had the advantage of not altering Nova. So imagine our surprise when the Nova-Cyborg joint meeting later that day rolled around, and the Nova cores were open to the idea of adding a blocking call in the build process to call out to Cyborg to do whatever preparation would be necessary to have the accelerator ready to go, so that when the VM is ready, any accelerators would also be ready to be used. I’m planning on staying in touch with the Cyborg team to help them however I can make this work.

On to Wednesday, not only did the Nova discussions begin, but the snow began to fall in Dublin.

Dublin morning
Dublin morning – the first snowfall of #SnowpenStack

As is the custom, we prepared an etherpad ahead of time with the various topics to discuss, and then organized it into a schedule so that we don’t rabbit-hole too deeply on any topic. If you look over that etherpad, you’ll see quite a bit of material to discuss. It would be silly for me to reproduce those topics and their conclusions here; instead, if you have an interest in Nova, reviewing that etherpad is the best way to get an understanding of what was decided (and what was not!).

The day’s discussions started off with Cells V2. Some of the more interesting topics were what to do when a cell goes down. For example, Nova should still be able to list all of a user’s instances even when a cell is down; they just won’t be able to interact with that instance through Nova. Another concern was more internal: are we going to remove the (few) upcalls from a cell to the outer-level API? While it has always been a design tenet that a cell cannot call the API-level services, it has been necessary in a few cases to bend that rule.

rooftop snow
The view from the area where lunch was served.

The afternoon was scheduled for Placement discussions, and there sure were enough of ’em! So much material to cover that it merited its own etherpad! And it’s a good thing we have an etherpad to record this stuff, because I’m writing this nearly two weeks after the fact, and I’ve already forgotten some of the things we discussed! So if you’re interested in any of the Placement discussions, that etherpad is probably your best source for information.

Thursday started off with the Nova-Cinder discussion. Now that multi-attach is a reality, we could finally focus on many of the other issues that have pushed to the background for a while. Again, for any particular topic, please refer to the Nova etherpad.

After that it was time for our team photo. We weren’t allowed onto the pitch at Croke Park, so the plan was to line up on the perimeter of the pitch to have the picture taken with the stadium in the background. But remember I mentioned that cold snap? Well, it was in full force, and we all bundled up to go outside for the photo.

Nova Team Photo Dublin

You think it was cold? 🙂 We had more discussions planned for the afternoon and Thursday, but by then we got word that they needed to have us all out of the stadium by 2pm so that they could send their workers home. The plan was to have people go back to their hotel, and the PTG would more or less continue with makeshift meeting areas in the hotel across the street from the stadium, where most attendees were staying. But since my hotel was further away, I headed back there and missed the rest of the events. All public transportation in Dublin had shut down!

bus sign shut down
All public transportation in Dublin was shut down for several days.

That also meant that Dublin Airport was shut down, canceling dozens of flights, including ours. We ended up having to stay in the hotel an extra 2 nights, and our hotel, the Maldron Parnell Square, was very accommodating. They kept their restaurant open, and some of the workers there told me that they couldn’t get home, so the hotel offered to put them up so that they could keep things running.

By Saturday things had cleared up enough that pretty much everything was open, and we rebooked our flight to leave Sunday. That left just enough time to enjoy a little more of what Dublin does best!

drinking guinness
Drinking a pint of Guinness, wearing my Irish wool sweater and Irish wool cap!

There was some discussion among the members of the OpenStack Board as to whether continuing to hold PTGs is a good idea. The main reason not to have them, in my opinion, is money. Without the flashy corporate sponsorships and expensive admission prices of the Summits, PTGs cost money to put on. It certainly isn’t because the PTG fails to meet its objective of bringing together the various development and deployment teams to make OpenStack better. Fortunately, the decision was to hold at least one more PTG, with the location still to be determined. Maybe by then enough people will realize that without a strong development process, all the fancy Summits in the world won’t make OpenStack better, and the PTGs are a critical part of that development process.

Leave a Reply