Add dynamic label with match_enhancements

[zabudskyi]

I need to add label with app field to be sent to alertmanger and then to the teams channel.
Here is enhancement

  add_app_label.py: |-
    from elastalert.enhancements import BaseEnhancement

    class AddAppLabelEnhancement(BaseEnhancement):
        def process(self, match):
            print('BeforeGet:', match)
            app_value = match.get('app', 'app_field_missing')
            print('AfterGet:', match)
            match['alertmanager_labels'] = {'service': app_value}
            print('Aftermatch:', match)

And match_enhancements is added to the alert

    match_enhancements:
    - "elastalert_modules.add_app_label.AddAppLabelEnhancement"

When I test rule, I get this label in the output

Aftermatch: <ommited> 'alertmanager_labels': {'service': 'validator-application'}}

But it is not added to the alert in teams channel. What can be wrong? What are further debug steps?

[zabudskyi]

According to tcpdump, label is not sent to alertmanager

[zabudskyi]

What I needed was

    alertmanager_fields:
      service: app