[ovirt-devel] rounding microseconds in vm conf update

[Juan Hernández]

On 06/21/2017 10:35 PM, Valentina Makarova wrote:
> Hello!
> 
> Ovirt sdk process updating of vm template with rounding of microseconds
> in creation_time.
> And vm is marked as vm which has a newer configuration because of this,
> but there is not a new configuration, all difference between current
> configuration and next_run configuration is creation_time. It is not
> correct. 
>   For example, diff between curl get-request for this state of vm  and
> next_run state is:
> [ovirt-system-tests]$ diff current_state.txt next_state.txt 
> 55c55
> <     <creation_time>2017-06-14T06:18:03*.987*-04:00</creation_time>
> ---
>>     <creation_time>2017-06-14T06:18:03*.000*-04:00</creation_time>
> 76a77
> 

The SDKs don't round anything, they use the same precision than the engine.

Is that with the latest version of the engine? There was a bug related
to this which was fixed in 4.2 already:

  Updating a VM with 'next_run=true' returns the current memory instead
of the next run memory
  https://bugzilla.redhat.com/1417201

The reason for that is that the 'creation_time' is stored with different
precision in the database and in the OVF file.

> And example how to request update for reach rounding is a test in
> ovirt_system_test:
> 
> @ovirtlago.testlib.with_ovirt_api
> def update_round(api):
>     vm = api.vms.get('vm0') #there vm.creation_time.isoformat() is a
> real datetime with microseconds
>     vm.update() #after this  vm.creation_time.isoformat() contains a
> real datetime with microseconds,
>     #but vm becames vm with newer configuration and 
>     # next_run creation time becomes rounded to seconds
> 
> Does anyone have idea how to fix this?
> 

The ideal way to avoid this kind of problems is to update objects
sending only the attributes that you really want to update. With version
3 of the SDK the only way to do that is to explicitly clear the
attributes that you don't want to send before calling the 'update' method:

  # Set the attributes that you want to update:
  vm.set_description('Update description')
  ...

  # Clear the 'creation_time' attribute so that it won't be sent
  # as part of the update:
  vm.set_creation_time(None)

  # Send the update request:
  vm.update()

With version 4 of the SDK it is simpler, as you need/should send only
the attributes that you want to update:

  vm_service.update(
      vm=types.Vm(
          description='Updated description',
          ...
      )
  )