Create OpenStack VMs in few seconds

Sean Mooney smooney at
Thu Mar 25 15:11:24 UTC 2021

On 25/03/2021 15:04, Jeremy Stanley wrote:
> On 2021-03-25 14:47:09 +0000 (+0000), Sean Mooney wrote:
>> nova does not support create a base vm and then doing a local live
>> migration or restore for memory snapshots to create another vm.
>> this approch likely has several security implciations that would
>> not be accpeatable in a multi tenant enviornment.
>> we have disucssed this type of vm creation in the past and
>> determined that it is not a valid implematnion of spawn. a virt
>> driver that precreate vms or copys an existing instance can be
>> faster but that virt driver is not considered a compliant
>> implementation.
>> so in short there is no way to achive this today in a compliant
>> openstack powered cloud.
> [...]
> The next best thing is basically what Nodepool[*] does: start new
> virtual machines ahead of time and keep them available in the
> tenant. This does of course mean you're occupying additional quota
> for whatever base "ready" capacity you've set for your various
> images/flavors, and that you need to be able to predict how many of
> what kinds of virtual machines you're going to need in advance.
> [*]

ya if you had premtible instances that would make that model a little 
more compeeling especially if you could move them form premtible to non 
premtable wehn you acutlly use them.

unfortunetly we also dont have the feature in nova today.

if the extra cost of precreating the instances was acceptable then yes 
using something like node pool could help but it requried a different 
way of interacting with  openstack as the consuming applicaiton

and it somewhat limits you in terems for your network/volumn config 
unless you modify them after teh fact you have rretrived a reserved 
instance form nodepool.

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