Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[Juan Hernández]

On 04/10/2016 12:16 PM, Yaniv Kaul wrote:
> 
> 
> On Sun, Apr 10, 2016 at 11:02 AM, Yedidyah Bar David  > wrote:
> 
> On Sun, Apr 10, 2016 at 10:43 AM, Barak Korren  > wrote:
> > Hi there, I use the following Python SDK snippet to create a template
> > from an existing VM:
> >
> > templ = ovirt.templates.add(
> > ovirtsdk.xml.Template(vm=vm, name=vm.name )
> > )
> >
> > This seems to launch a template creation task in a non-blocking
> > manner, which makes the next command I run, which tries to delete the
> > VM, fail because the VM is still locked by the template creation task.
> >
> > Is there a way to block on the template creation task and not return
> > to the code until it finishes?
> 
> I don't think so, but you can loop waiting, see e.g.:
> 
> http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm
> 
> 
> I wish we could have an extra parameters on the Python SDK that would do
> this exact loop for us, since essentially most use cases require this.
> I'm not sure it is relevant only for template creation, btw.
> What is also more annoying, is that this loop (IIRC) will never break,
> if something bad happens and the template ends up in a state != down
> (such as locked).
> (Same issue I've just had with host installation - Iv'e waited endlessly
> for it to be in 'up' state, only to find out it ended in
> 'installed_failed' state).
> Y.
>  

The API already has mechanisms to run operations in a synchronous
fashion, and they caused more problems than they solved.

For example, all actions have an "async" parameter, that indicates, when
the values is "false", if the API should wait for all the reported
backend activities to finish. The problem is that the meaning of
"reported backend activities" may be different from what you expect:
some backend activities aren't reported, see bug 1199011.

In addition the backend doesn't have any commitment to keep reporting
activities in a backwards compatible fashion. What is reported in
version 3.5 may not be reported in version 3.6.

So the only reliable mechanism to wait for activities to finish is to
check them explicitly, looping and checking the status. This is the only
mechanism that we can support and recommend.

-- 
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Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[Barak Korren]

 Is there a way to block on the template creation task and not
 return to the code until it finishes?
>>>
>>>
>>> I don't think so, but you can loop waiting, see e.g.:
>>>
>>> http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm
>>> [2]
>>
>>
>> I wish we could have an extra parameters on the Python SDK that would
>> do this exact loop for us, since essentially most use cases require
>> this.

I see most SDK action-creating methods have an optional
"correlation_id" string argument, could that be used to somehow track
the task and figure out when it is done?


-- 
Barak Korren
bkor...@redhat.com
RHEV-CI Team
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Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[nicolas]

El 2016-04-10 11:16, Yaniv Kaul escribió:

On Sun, Apr 10, 2016 at 11:02 AM, Yedidyah Bar David 
wrote:


On Sun, Apr 10, 2016 at 10:43 AM, Barak Korren 
wrote:

Hi there, I use the following Python SDK snippet to create a

template

from an existing VM:

     templ = ovirt.templates.add(
         ovirtsdk.xml.Template(vm=vm, name=vm.name [1])
     )

This seems to launch a template creation task in a non-blocking
manner, which makes the next command I run, which tries to delete

the

VM, fail because the VM is still locked by the template creation

task.


Is there a way to block on the template creation task and not

return

to the code until it finishes?


I don't think so, but you can loop waiting, see e.g.:



http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm

[2]


I wish we could have an extra parameters on the Python SDK that would
do this exact loop for us, since essentially most use cases require
this.
I'm not sure it is relevant only for template creation, btw.
What is also more annoying, is that this loop (IIRC) will never break,
if something bad happens and the template ends up in a state != down
(such as locked).
(Same issue I've just had with host installation - Iv'e waited
endlessly for it to be in 'up' state, only to find out it ended in
'installed_failed' state).
Y.



I have had some issues related to this, I've opened a couple of BZs (for 
different issues, though):


https://bugzilla.redhat.com/show_bug.cgi?id=1245630

https://bugzilla.redhat.com/show_bug.cgi?id=1315874

Currently the "poorman's wait method" that I detailed on the second BZ 
is the method I'm following to check whether state is "Ok".


Regards.
 



--
Didi

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Links:
--
[1] http://vm.name
[2] 
http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm

[3] http://lists.ovirt.org/mailman/listinfo/users

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Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[Nir Soffer]

On Sun, Apr 10, 2016 at 1:16 PM, Yaniv Kaul  wrote:
>
>
> On Sun, Apr 10, 2016 at 11:02 AM, Yedidyah Bar David 
> wrote:
>>
>> On Sun, Apr 10, 2016 at 10:43 AM, Barak Korren  wrote:
>> > Hi there, I use the following Python SDK snippet to create a template
>> > from an existing VM:
>> >
>> > templ = ovirt.templates.add(
>> > ovirtsdk.xml.Template(vm=vm, name=vm.name)
>> > )
>> >
>> > This seems to launch a template creation task in a non-blocking
>> > manner, which makes the next command I run, which tries to delete the
>> > VM, fail because the VM is still locked by the template creation task.
>> >
>> > Is there a way to block on the template creation task and not return
>> > to the code until it finishes?
>>
>> I don't think so, but you can loop waiting, see e.g.:
>>
>> http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm
>
>
> I wish we could have an extra parameters on the Python SDK that would do
> this exact loop for us, since essentially most use cases require this.
> I'm not sure it is relevant only for template creation, btw.
> What is also more annoying, is that this loop (IIRC) will never break, if
> something bad happens and the template ends up in a state != down (such as
> locked).
> (Same issue I've just had with host installation - Iv'e waited endlessly for
> it to be in 'up' state, only to find out it ended in 'installed_failed'
> state).

What we need is way to wait for events. For example, perform a request that
never completes, sending events as json/xml fragments and chunked encoding.

Here is an example:
https://dev.twitter.com/streaming/overview

Nir
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Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[Yaniv Kaul]

On Sun, Apr 10, 2016 at 11:02 AM, Yedidyah Bar David 
wrote:

> On Sun, Apr 10, 2016 at 10:43 AM, Barak Korren  wrote:
> > Hi there, I use the following Python SDK snippet to create a template
> > from an existing VM:
> >
> > templ = ovirt.templates.add(
> > ovirtsdk.xml.Template(vm=vm, name=vm.name)
> > )
> >
> > This seems to launch a template creation task in a non-blocking
> > manner, which makes the next command I run, which tries to delete the
> > VM, fail because the VM is still locked by the template creation task.
> >
> > Is there a way to block on the template creation task and not return
> > to the code until it finishes?
>
> I don't think so, but you can loop waiting, see e.g.:
>
> http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm


I wish we could have an extra parameters on the Python SDK that would do
this exact loop for us, since essentially most use cases require this.
I'm not sure it is relevant only for template creation, btw.
What is also more annoying, is that this loop (IIRC) will never break, if
something bad happens and the template ends up in a state != down (such as
locked).
(Same issue I've just had with host installation - Iv'e waited endlessly
for it to be in 'up' state, only to find out it ended in 'installed_failed'
state).
Y.


>
> --
> Didi
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>
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Re: [ovirt-users] Creating templates in a blocking fashion from Python SDK

[Yedidyah Bar David]

On Sun, Apr 10, 2016 at 10:43 AM, Barak Korren  wrote:
> Hi there, I use the following Python SDK snippet to create a template
> from an existing VM:
>
> templ = ovirt.templates.add(
> ovirtsdk.xml.Template(vm=vm, name=vm.name)
> )
>
> This seems to launch a template creation task in a non-blocking
> manner, which makes the next command I run, which tries to delete the
> VM, fail because the VM is still locked by the template creation task.
>
> Is there a way to block on the template creation task and not return
> to the code until it finishes?

I don't think so, but you can loop waiting, see e.g.:

http://www.ovirt.org/develop/api/pythonapi/#create-a-template-from-vm
-- 
Didi
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[ovirt-users] Creating templates in a blocking fashion from Python SDK

[Barak Korren]

Hi there, I use the following Python SDK snippet to create a template
from an existing VM:

templ = ovirt.templates.add(
ovirtsdk.xml.Template(vm=vm, name=vm.name)
)

This seems to launch a template creation task in a non-blocking
manner, which makes the next command I run, which tries to delete the
VM, fail because the VM is still locked by the template creation task.

Is there a way to block on the template creation task and not return
to the code until it finishes?

Thanks,

-- 
Barak Korren
bkor...@redhat.com
RHEV-CI Team
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