[openstack-dev] [nova][placement] Trying to summarize bp/glance-image-traits scheduling alternatives for rebuild

Matt Riedemann mriedemos at gmail.com
Wed May 2 22:45:37 UTC 2018

On 5/2/2018 5:39 PM, Jay Pipes wrote:
> My personal preference is to add less technical debt and go with a 
> solution that checks if image traits have changed in nova-api and if so, 
> simply refuse to perform a rebuild.

So, what if when I created my server, the image I used, let's say 
image1, had required trait A and that fit the host.

Then some external service removes (or somehow changes) trait A from the 
compute node resource provider (because people can and will do this, 
there are a few vmware specs up that rely on being able to manage traits 
out of band from nova), and then I rebuild my server with image2 that 
has required trait A. That would match the original trait A in image1 
and we'd say, "yup, lgtm!" and do the rebuild even though the compute 
node resource provider wouldn't have trait A anymore.

Having said that, it could technically happen before traits if the 
operator changed something on the underlying compute host which 
invalidated instances running on that host, but I'd think if that 
happened the operator would be migrating everything off the host and 
disabling it from scheduling before making whatever that kind of change 
would be, let's say they change the hypervisor or something less drastic 
but still image property invalidating.




More information about the OpenStack-dev mailing list