OpenStack Summit Liberty from a Ceilometer & Gnocchi point of view

Tuesday 26 May 2015 OpenStack, Ceilometer, Gnocchi Comments

Last week I was in Vancouver, BC for the OpenStack Summit, discussing the new Liberty version that will be released in 6 months.

I've attended the summit mainly to discuss and follow-up new developments on Ceilometer, Gnocchi and Oslo. It has been a pretty good week and we were able to discuss and plan a few interesting things.

Ops feedback

We had half a dozen Ceilometer sessions, and the first one was dedicated to getting feedbacks from operators using Ceilometer. We had a few operators present, and a few of the Ceilometer team. We had constructive discussion, and my feeling is that operators struggles with 2 things so far: scaling Ceilometer storage and having Ceilometer not killing the rest of OpenStack.

We discussed the first point as being addressed by Gnocchi, and I presented a bit Gnocchi itself, as well as how and why it will fix the storage scalability issue operators encountered so far.

Ceilometer putting down the OpenStack installation is more interesting problem. Ceilometer pollsters request information from Nova, Glance… to gather statistics. Until Kilo, Ceilometer used to do that regularly and at fixed interval, causing high pike load in OpenStack. With the introduction of jitter in Kilo, this should be less of a problem. However, Ceilometer hits various endpoints in OpenStack that are poorly designed, and hitting those endpoints of Nova or other components triggers a lot of load on the platform. Unfortunately, this makes operators blame Ceilometer rather than blaming the components being guilty of poor designs. We'd like to push forward improving these components, but it's probably going to take a long time.


When I started the Gnocchi project last year, I pretty soon realized that we would be able to split Ceilometer itself in different smaller components that could work independently, while being able to leverage each others. For example, Gnocchi can run standalone and store your metrics even if you don't use Ceilometer – nor even OpenStack itself.

My fellow developer Chris Dent had the same idea about splitting Ceilometer a few months ago and drafted a proposal. The idea is to have Ceilometer split in different parts that people could assemble together or run on their owns.

Interestingly enough, we had three 40 minutes sessions planned to talk and debate about this division of Ceilometer, though we all agreed in 5 minutes that this was the good thing to do. Five more minutes later, we agreed on which part to split. The rest of the time was allocated to discuss various details of that split, and I engaged to start doing the work with Ceilometer alarming subsystem.

I wrote a specification on the plane bringing me to Vancouver, that should be approved pretty soon now. I already started doing the implementation work. So fingers crossed, Ceilometer should have a new components in Liberty handling alarming on its own.

This would allow users for example to only deploys Gnocchi and Ceilometer alarm. They would be able to feed data to Gnocchi using their own system, and build alarms using Ceilometer alarm subsystem relying on Gnocchi's data.


We didn't have a Gnocchi dedicated slot – mainly because I indicated I didn't feel we needed one. We anyway discussed a few points around coffee, and I've been able to draw a few new ideas and changes I'd like to see in Gnocchi. Mainly changing the API contract to be more asynchronously so we can support InfluxDB more correctly, and improve Carbonara (the library we created to manipulate timeseries) based drivers to be faster.

All of those should – plus a few Oslo tasks I'd like to tackle – should keep me busy for the next cycle!