[openstack-dev] [Horizon] Suggestions for handling new panels and refactors in the future

Tripp, Travis S travis.tripp at hpe.com
Fri Oct 9 20:35:59 UTC 2015

Hi Doug!

I think the is a great discussion topic and you summarize your points very nicely!

 I wish you’d responded to this thread, though:  https://openstack.nimeyo.com/58582/openstack-dev-horizon-patterns-for-angular-panels, because it is talking about the same problem. This is option 3 I mentioned there and I do think this is still a viable option to consider, but we should discuss all the options.

Please consider that thread as my initial response to your email… and let’s keep discussing!


From: Douglas Fish
Reply-To: OpenStack List
Date: Friday, October 9, 2015 at 8:42 AM
To: OpenStack List
Subject: [openstack-dev] [Horizon] Suggestions for handling new panels and refactors in the future

I have two suggestions for handling both new panels and refactoring existing panels that I think could benefit us in the future:
1) When we are creating a panel that's a major refactor of an existing it should be a new separate panel, not a direct code replacement of the existing panel
2) New panels (include the refactors of existing panels) should be developed in an out of tree gerrit repository.

Why make refactors a separate panel?

I was taken a bit off guard after we merged the Network Topology->Curvature improvement: this was a surprise to some people outside of the Horizon community (though it had been discussed within Horizon for as long as I've been on the project). In retrospect, I think it would have been better to keep both the old Network Topology and new curvature based topology in our Horizon codebase. Doing so would have allowed operators to perform A-B/ Red-Black testing if they weren't immediately convinced of the awesomeness of the panel. It also would have allowed anyone with a customization of the Network Topology panel to have some time to configure their Horizon instance to continue to use the Legacy panel while they updated their customization to work with the new panel.

Perhaps we should treat panels more like an API element and take them through a deprecation cycle before removing them completely. Giving time for customizers to update their code is going to be especially important as we build angular replacements for python panels. While we have much better plugin support for angular there is still a learning curve for those developers.

Why build refactors and new panels out of tree?

First off, it appears to me trying to build new panels in tree has been fairly painful. I've seen big long lived patches pushed along without being merged. It's quite acceptable and expected to quickly merge half-complete patches into a brand new repository - but you can't behave that way working in tree in Horizon. Horizon needs to be kept production/operator ready. External repositories do not. Merging code quickly can ease collaboration and avoid this kind of long lived patch set.

Secondly, keeping new panels/plugins in a separate repository decentralizes decisions about which panels are "ready" and which aren't. If one group feels a plugin is "ready" they can make it their default version of the panel, and perhaps put resources toward translating it. If we develop these panels in-tree we need to make a common decision about what "ready" means - and once it's in everyone who wants a translated Horizon will need to translate it.

Finally, I believe developing new panels out of tree will help improve our plugin support in Horizon. It's this whole "eating your own dog food" idea. As soon as we start using our own Horizon plugin mechanism for our own development we are going to become aware of it's shortcomings (like quotas) and will be sufficiently motivated to fix them.

Looking forward to further discussion and other ideas on this!

Doug Fish

More information about the OpenStack-dev mailing list