Improvement: Allow Golang templates for notifier headers

[freefd]

Allow to use Golang template engine for notification headers, as it is already used for the notification body.
Mostly useful for Webhook notifier.

Also, when implemented, the hard-coded X-Actions header for Ntfy can be moved to default Ntfy configuration.

[0x2142]

Sounds good. I'll add it to the backlog 👍

[freefd]

Sample usage for Ntfy:

    headers:
      - Authorization: Basic {{ env.Getenv "FN_NTFY_AUTH_BASIC" }}
      - X-Priority: "{{ if ge (len .Zones ) 1 }} 4{{ else }} 3{{ end }}"
      - X-Tags: "{{ if ge (len .Zones ) 1 }} rotating_light, {{ end }}walking"

Produces a message with normal (3) severity when the object is in the camera FOV but out of any zone:

And produces a message with high (4) priority when the object crossed the zone:

The Ntfy app is configured to only alert on messages of high severity and to keep a silent on messages with normal severity, so as not to bother the user too often.

[0x2142]

Appreciate you sharing! It's always interesting to see how this is getting used 😊

[freefd]

@0x2142, if you'll decide to add this example to the docs, I wouldn't mind :)