Open Stack

I've been thinking a bit more about how TripleO updates are developing specifically with regards to compute nodes. What is commonly called the "update story" I think.

As I understand it we expect people to actually have to reboot a compute node in the cluster in order to deploy an update. This really worries me because it seems like way overkill for such a simple operation. Lets say all I need to deploy is a simple change to Nova's libvirt driver. And I need to deploy it to *all* my compute instances. Do we really expect people to actually have to reboot every single compute node in their cluster for such a thing. And then do this again and again for each update they deploy?

I understand the whole read only images thing plays into this too... but I'm wondering if there is a middle ground where things might work better. Perhaps we have a mechanism where we can tar up individual venvs from /opt/stack/ or perhaps also this is an area where real OpenStack packages could shine. It seems like we could certainly come up with some simple mechanisms to deploy these sorts of changes with Heat such that compute host reboot can be avoided for each new deploy.

Dan