Open Stack

On 02/20/2014 11:38 AM, Matt Riedemann wrote:
>
>
> On 2/19/2014 4:05 PM, Matt Riedemann wrote:
>> The os-hosts OS API extension [1] showed up before I was working on the
>> project and I see that only the VMware and XenAPI drivers implement it,
>> but was wondering why the libvirt driver doesn't - either no one wants
>> it, or there is some technical reason behind not implementing it for
>> that driver?
>>
>> [1]
>> http://docs.openstack.org/api/openstack-compute/2/content/PUT_os-hosts-v2_updateHost_v2__tenant_id__os-hosts__host_name__ext-os-hosts.html

> By the way, am I missing something when I think that this extension is
> already covered if you're:
>
> 1. Looking to get the node out of the scheduling loop, you can just
> disable it with os-services/disable?
>
> 2. Looking to evacuate instances off a failed host (or one that's in
> "maintenance mode"), just use the evacuate server action.

In compute/api.py the API.evacuate() routine errors out if 
self.servicegroup_api.service_is_up(service) is true, which means that 
you can't evacuate from a compute node that is "disabled", you need to 
migrate instead.

So, the alternative is basically to disable the service, then get a list 
of all the servers on the compute host, then kick off the migration 
(either cold or live) of each of the servers.  Then because migration 
uses a "cast" instead of a "call" you need to poll all the migrations 
for success or late failures.  Once you have no failed migrations and no 
servers running on the host then you're good.

Chris