Open Stack

On 2/28/2019 3:35 AM, Zhenyu Zheng wrote:
> And when we can support assign tag when attach volume to 
> shelved_offloaded instances,
> we then perform the reset and update action.

Honestly if we're going to do all of that I would rather *not* do the 
root detach/attach volume stuff if it just means we have to change it 
later to allow tagging the new root volume.

However, I don't think we really need to wait for driver capabilities 
traits-based scheduling with a placement request filter either. What is 
stopping us from simply, within the same microversion for root 
detach/attach, also lift the restriction on being able to attach a 
volume to a shelved offloaded instance with a tag? I realize the 
restriction was there because we didn't know where the instance would 
unshelve and it could be on a compute host that doesn't support device 
tags, but that is also true of the initial server create, so if we're 
going to support the create scenario in the API I don't see why we don't 
support the shelved offloaded scenario too.

We don't have any policy rules in place against using tags if you're a 
full VIO shop with only vmware and don't support tags, but we could 
always add that to 403 requests to use device tags. Otherwise if you're 
using libvirt then this would already work.

I realize this is a late change in the design for the root volume 
detach/attach spec, but I think the two need to go together to avoid 
releasing a half-baked feature.

-- 

Thanks,

Matt