[ovirt-users] Python API question
Juan Hernández
jhernand at redhat.com
Fri Jan 15 10:04:45 UTC 2016
On 01/15/2016 05:23 AM, Colin Coe wrote:
> Hi all
>
> I've written a Python script to take nightly snapshots of VMs which are
> kept for x days. After x days the snapshot is deleted.
>
> I can't work out how to wait for the snapshot deletion to complete. I
> know how to do it for creating the snapshot but I've not been able to
> get it right for the deletion.
>
>
> api.vms.get(VM_NAME).snapshots.add(params.Snapshot(description=SNAPSHOT_NAME,
> vm=api.vms.get(VM_NAME), persist_memorystate=True))
> while api.vms.get(VM_NAME).status.state == 'image_locked':
> sleep(1)
>
> Any ideas?
>
> Thanks
>
> CC
>
>
The more reliable way to wait till the snapshot is effectively deleted
is just to try to get it, and finish when the result is "None":
snapshot.delete()
while vm.snapshots.get(id=snapshot.get_id()) is not None:
sleep(1)
Alternatively you can use the return of the delete operation. It returns
an "Action" object, that contains a reference to the job that was
started to delete the snapshot. The XML representation looks like this:
<action>
<job href="/api/jobs/f6e4279a-a8e1-44a3-86db-d53336b0eb5a"
id="f6e4279a-a8e1-44a3-86db-d53336b0eb5a"/>
<status>
<state>complete</state>
</status>
</action>
As you can see that contains a link to the job. With the Python SDK you
can use it as follows:
# Get the id of the job:
action = snapshot.delete()
job_id = action.get_job().get_id()
# Wait till the job is finished:
while api.jobs.get(id=job_id).get_status().get_state() != 'FINISHED':
time.sleep(1)
This is less reliable, because actions may or may not return a job, and
that depends on how the action is implemented in the engine, and there
is no backwards compatibility guarantee for that. A minor change in the
engine may result in the job not being returned.
So my suggestion is to use the simple loop to check if the snapshot exists.
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