onevnet update (from sunstone) may cause unnecessary error

[paczerny]

Description
If Virtual Network has has empty attributes like PHYDEV and VLAN_ID. Update from Sunstone doesn't include these empty values, this is detected as change in the Network, which needs nic-update action. This action may fail because of empty PHYDEV

To Reproduce

$ cat vnet.tmpl
NAME = internal
BRIDGE = "virbr0"
BRIDGE_TYPE = "linux"
DNS = "8.8.8.8"
GATEWAY = "192.168.122.1"
PHYDEV = ""
VN_MAD = "fw"
AR=[
    TYPE = "IP4",
    IP   = "192.168.122.150",
    SIZE = "10"
]
$ onevnet instantiate vnet.tmpl

Attach the Network to running VM.
In Sunstone go to Virtual Network and trigger update without modifying any value.
The Network will change to ERROR state
In oned.log you should see error

Message received: UPDATENIC FAILURE 1 0  fw: ERROR: update_nic: Command "sudo -n ip link set nomaster" failed. ERROR: update_nic: Not enough information: "dev" argument is required. Not enough information: "dev" argument is required. ExitCode: 255

Expected behavior
Avoid unnecessary calls to nic-update. onevnet update which doesn't change any value should not cause network error.

Details

• Affected Component: Sunstone, oned, network drivers
• Version: 6.6+

Additional context
Should be solved in two steps:

• The network driver should check the PHYDEV attribute is not empty
• Better detection of changed attributes in VirtualNetwork::set_updated_attributes

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)

[paczerny]

Link to forum thread, which reported the issue