Cannot enable collect_iptables_metrics

[Haw Loeung]

Hi,

I'm trying to enable `collect_iptables_metrics` on various models but that's failing.

It looks maybe to be with this bit of code:

| @hook("update-status")
| def update_status():
| changed = charms.reactive.helpers.data_changed(
| "detect_changes", get_base_inputs(), hash_type="sha256"
| )
| if changed:
| clear_flag("telegraf.configured")
| clear_flag("telegraf.apt.configured")
| clear_flag("telegraf.snap.configured")
| ...

So when you run `juju config telegraf-u-r-c collect_iptables_metrics=true`, a `config-changed` is fired but does nothing. You wait a bit for `update-status` to fire but by then, `detect_changes` returns false. This is from adding a bit of debug print:

2023-05-12 05:58:08 DEBUG unit.telegraf-u-r-c/5.update-status logger.go:60 HAW detect_changes False:

I think the logic should really change to rather than `update-status` to:

| @reactive.when('config.changed')
| def config_changed():
| clear_flag("telegraf.configured")
| clear_flag("telegraf.apt.configured")
| clear_flag("telegraf.snap.configured")
| ....
|
|
| @hook("update-status")
| def update_status():
| if is_flag_set("telegraf.configured"):
| service = get_service()
| if not host.service_running(service):
| hookenv.status_set("blocked", "Service not running: {}".format(service))
| else:
| hookenv.status_set(
| "active",
| "Monitoring {}{}".format(get_remote_unit_name(), get_revision()),

It also reduces the time from making a `juju config` change to when it's live.