"config-changed" hook failed with required_mtu set: TypeError: argument of type 'int' is not iterable

[Nobuto Murata]

How to reproduce:

1. deploy the edge charm:

$ juju deploy magpie --channel edge -n3
Located charm "magpie" in charm-hub, revision 3
Deploying "magpie" from charm-hub charm "magpie", revision 3 in channel edge on focal

2. set required_mtu

$ juju config magpie required_mtu=1500

unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Invoking reactive handler: reactive/magpie.py:128:check_all_node
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log MTU for iface: ens5 is 9001
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Running iperf test
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Pinging unit_id: 0
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Ping OK for unit_id: 0
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Pinging unit_id: 2
unit-magpie-1: 10:18:24 INFO unit.magpie/1.juju-log Ping OK for unit_id: 2
unit-magpie-1: 10:18:24 ERROR unit.magpie/1.juju-log Hook error:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-magpie-1/.venv/lib/python3.8/site-packages/charms/reactive/__init__.py", line 74, in main
    bus.dispatch(restricted=restricted_mode)
  File "/var/lib/juju/agents/unit-magpie-1/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 390, in dispatch
    _invoke(other_handlers)
  File "/var/lib/juju/agents/unit-magpie-1/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 359, in _invoke
    handler.invoke()
  File "/var/lib/juju/agents/unit-magpie-1/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 181, in invoke
    self._action(*args)
  File "/var/lib/juju/agents/unit-magpie-1/charm/reactive/magpie.py", line 135, in check_all_node
    _set_states(check_nodes(nodes))
  File "/var/lib/juju/agents/unit-magpie-1/charm/lib/charms/layer/magpie_tools.py", line 588, in check_nodes
    if "failed" not in mtu:
TypeError: argument of type 'int' is not iterable

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-magpie/+/843132

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-magpie/+/843132
Committed: https://opendev.org/openstack/charm-magpie/commit/f22166f6ece34656ffbaa1c7093ce0aae3973ed4
Submitter: "Zuul (22348)"
Branch: master

commit f22166f6ece34656ffbaa1c7093ce0aae3973ed4
Author: Nobuto Murata <email address hidden>
Date: Tue May 24 20:38:42 2022 +0900

    Fix a type error in the MTU evaluation

    To avoid the following error since required_mtu is int:
    TypeError: argument of type 'int' is not iterable

    Closes-Bug: #1973838
    Change-Id: I36796018a537e6030bf46f283f1c74ef1fe4772c