cloudinit.net refactor: find_fallback_nic

[ubuntu-server-builder]

This bug was originally filed in Launchpad as LP: #1884606

Launchpad details

affected_projects = []
assignee = None
assignee_name = None
date_closed = None
date_created = 2020-06-22T20:30:35.898363+00:00
date_fix_committed = None
date_fix_released = None
id = 1884606
importance = wishlist
is_complete = False
lp_url = https://bugs.launchpad.net/cloud-init/+bug/1884606
milestone = None
owner = oddbloke
owner_name = Dan Watkins
private = False
status = triaged
submitter = oddbloke
submitter_name = Dan Watkins
tags = ['net-refactor']
duplicates = []

Launchpad user Dan Watkins(oddbloke) wrote on 2020-06-22T20:30:35.898363+00:00

This bug is tracking part of the refactor of cloudinit.net into
cloudinit.distros.networking, specifically the refactoring of the function
named in the title of this bug. See [0] for further details.

[0] https://cloudinit.readthedocs.io/en/latest/topics/hacking.html#cloudinit-net-cloudinit-distros-networking-hierarchy

[ubuntu-server-builder]

Launchpad user Ryan Harper(raharper) wrote on 2020-06-24T19:05:31.646771+00:00

It would be good to refactor this to match what's in cloudinit/net/init.py:find_fallback_nic_linux() where we're looking for connected devices...

carrier = read_sys_net_int(interface, 'carrier')
if carrier:
connected.append(interface)
continue

check if nic is dormant or down, as this may make a nick appear to

not have a carrier even though it could acquire one when brought

online by dhclient

dormant = read_sys_net_int(interface, 'dormant')
if dormant:
possibly_connected.append(interface)
continue
operstate = read_sys_net_safe(interface, 'operstate')
if operstate in ['dormant', 'down', 'lowerlayerdown', 'unknown']:
possibly_connected.append(interface)
continue

Original discussion here:
https://github.com/canonical/cloud-init/pull/453/files#r444272062