How to select template based on label

Grafana Alerting
1

TL;DR How do I use a label to select which template to use? (Nest variable in expression)

I am trying to use one contact point to send 2 different templates.

One template would be used for a missed check in.
The other would be for a parameter, such as high CPU usage.

When I fire an alert, I’d like to have the following labels:

  • name: “Service A”
  • contact: “Teams”
  • message_template: “missed_checkin”
  • metric_name: “CPU”

The metric_name would be an optional label, only used in the second template.
The message_template would be either “missed_checkin” or “metric_threshold”

In the contact point’s message I have tried to use the following

{{ range .Alerts.Firing }}
     {{ template "${.Labels.message_template}_firing".}}
{{ end }}
{{ range .Alerts.Resolved }}
     {{ template "${.Labels.message_template}_resolved".}}
{{ end }}

With the following templates defined outside the contact point

{{ define "missed_checkin_firing" }}
  {{ range .}}
     {{ .Labels.Name }} is down.
  {{ end }}
{{ end }}

{{ define "missed_checkin_resolved" }}
  {{ range .}}
     {{ .Labels.Name }} is back up.
  {{ end }}
{{ end }}

{{ define "metric_threshold_firing" }}
  {{ range .}}
     {{ .Labels.Name }} has high {{ .Labels.metric_name }} usage.
  {{ end }}
{{ end }}

{{ define "metric_threshold_resolved" }}
  {{ range .}}
     {{ .Labels.Name }}'s high {{ .Labels.metric_name }} usage has resolved.
  {{ end }}
{{ end }}