Add custom dynamic variable to Alertmanager Transport


For now I see that we can put custom value as label for Alertmanager in the corresponding transport.
But it is only static string value.
I needed to add a dynamic label to get information such as the corresponding port name for a Port down alert.

The following lines of code worked for me. (in ./LibreNMS/Alert/Transport/Alertmanager.php in function contactAlertmanager)

    # Add ifName in case of port alert
    if (!empty($obj['faults'][1]['ifName'])) {
        $data[0]['labels']['ifName'] = $obj['faults'][1]['ifName'];

But I was wondering if it is useful to add the possibility to add those custom label and reach all the $alert[‘faults’] value.

I can propose a PR for this but first I need some advice please.

Should I add a new textarea in the Alertmanager transport popup or use the existing one called Alertmanager Options and add like a prefix to handle dynamic value instead of static one.

Thanks in advance for your help and have a nice day!

I made a first proposal
Please tell me if there is something more to do with it.
Have a nice week-end!