enable updating VNF parameters


This proposal aims at supporting to update parameters of created VNF.

Problem description

Current Tacker supports updating only config attribute of VNFs [1] and does not support updating param_values of VNFs. So, operators have to re-create the VNF if they want to update parameters. This spec enables updating the parameters without a VNF re-creation.

Use case

For example, some VNFs are deployed with a different priority on the limited infra resources and scale-up of the higher priority VNF will be expected due to increased demand in certain periods for upcoming events like concerts, festivals or sport games. Operators of higher priority VNF need to reserve resources for their VNF so that the required resources aren’t consumed by other VNFs.

The resource reservation function that current Tacker supports [2] enables extending resources during the certain periods by applying a reservation-id that was issued at reserving the resource to the VNF. Operators need to update the reservation-id because such a large-scale event usually occurs multiple times. Operators can prepare for such events without re-creating VNFs by introducing this parameter updating function.

Proposed change

  • Enabling to update parameter in vnf update.

Adding a new parameter –param-file to openstack vnf set command.

openstack vnf set --param-file PARAM-FILE <VNF>

parameters here means inputs parameters in VNFDs. So users have to parameterize what they want to update later in their VNFDs before creating VNFs. For example, the parameters include flavor, image, network, etc. like below. The detail is described in [3].

:caption: Example Parameterized VNFD
tosca_definitions_version: tosca_simple_profile_for_nfv_1_0_0

description: VNF TOSCA template with input parameters

  template_name: sample-tosca-vnfd

      type: string
      description: Image Name

      type: string
      description: Flavor Information

      type: string
      description: management network

      type: tosca.nodes.nfv.VDU.Tacker
        image: {get_input: image_name}
        flavor: {get_input: flavor}
        availability_zone: nova

      type: tosca.nodes.nfv.VL
        network_name: {get_input: network}
        vendor: Tacker

Updated values of parameters are described in parameter file.

:caption: Example parameter file
image_name: cirros-0.4.0-x86_64-disk
flavor: m1.tiny
network: net_mgmt
  • internal updating procedure

When parameter update, Tacker issues Heat stack update with setting True to existing flag to keep stack resources which do not consist updating parameter. It depends on the updated property if parameter updating brings re-creation of the stack resource or not. For example, updating image property of OS::Nova::Server resource type causes replacement of its VM but name property doesn’t. The detail is described in [4] [5] .

    # run stack update
    stack_update_param = {
    'parameters': update_values,
    'existing': True}
heatclient.update(vnf_id, **stack_update_param)
  • miscellaneous error handling

Users can use either config or parameter file, but not both at the same time. It’s because updating config may fail if VM re-creation occurs by updating parameter.

class UpdateVNF(command.ShowOne):
    _description = _("Update a given VNF.")

    def get_parser(self, prog_name):
        parser = super(UpdateVNF, self).get_parser(prog_name)
        group = parser.add_mutually_exclusive_group(required=True)
            help=_('YAML file with VNF configuration'))
            help=_('Specify config YAML data'))
            help=_('Specify parameter yaml file'))
            help=_("VNF to update (name or ID)"))
        return parser
:caption: Example error message
openstack vnf set --param-file PARAM-FILE --config CONFIG <VNF>
openstack vnf set: error: argument --config: not allowed with argument --param-file

If there is no difference between parameter values that are passed by vnf set command and current, Tacker cancels updating parameters with warning messages. It prevents unnecessary updating processes.

# check update values
update_values = {}
for key, value in update_param_dict.items():
    if update_param_dict[key] != param_dict[key]:
        update_values[key] = value
if not update_values:
    raise vnfm.VNFUpdateInvalidInput(
        reason="WARNING: parameter is same value")
:caption: Example warning message
openstack vnf set --param-file PARAM-FILE <VNF>
WARNING: parameter is same value



Data model impact


REST API impact

Adding “param_values” to “Request Parameters” of Update VNF API.

Security impact


Notifications impact


Other end user impact


Performance Impact


Other deployer impact


Developer impact




Primary assignee:
Hiroyuki Jo <jo.hiroyuki@lab.ntt.co.jp>

Work Items

  • Adding “param-file” argument to vnf set command in python-tackerclient.
  • Adding a function to get the difference between existing parameter and new parameter to Tacker.
  • Adding a function to call stack update with new parameter to Tacker
  • Unit Tests
  • Functional Tests
  • Update documentation




Unit and functional test cases will be added for updating VNF by applying new parameter to existing VNF

Documentation Impact

Adding “Updating VNF” to tacker/doc/source/user/vnfm_usage_guide.rst