Add utility functions to Message Templates

[davidatkinsondoyle]

💡 Idea

As a Notification Publisher
I would like like utility template functions to be available in message template
So that I can perform more advanced string manipulation in templates

Issues raised as outcome of thread on Discord.

Example Solution, using splitList and trim functions form sprig

Using the Slack Webhook format Alert Service in TrueNas emits a payload as below;

{"text": "TrueNAS @ truenasserver.some.domain\n\nNew alerts:\n* Job \"some notification\" succeeded.\n\n\n* Job \"some notification\" succeeded.\n\n\n\nThese alerts have been cleared:\n* Job \"some notification\" succeeded.\n\n\n* Job \"some notification\" succeeded.\n\n\n\nCurrent alerts:\n* Job 'some notification' finished.\n\n\n* Job \"some notification\" succeeded.\n\n\n* Replication \"some notification\" succeeded.\n\n\n\n"}

To turn this payload into a more usable nfty notification, with a title and message;

Title Template

{{- index (splitList "\n" .text) 0 -}}

Renders;

TrueNAS @ truenasserver.some.domain

Message Template

{{ range $index, $value := (splitList "\n\n" .text) }}
{{if eq $index 0}}{{else}}{{. | trim }}{{end}}{{end}}

Renders;

New alerts:

• Job "some notification" succeeded.
• Job "some notification" succeeded.

These alerts have been cleared:

• Job "some notification" succeeded.
• Job "some notification" succeeded.

Current alerts:

• Job 'some notification' finished.
• Job "some notification" succeeded.
• Replication "some notification" succeeded.

Possible implementations / Inspiration

• sprig
• https://github.com/hairyhenderson/gomplate

💻 Target components
ntfy server