Create listen directives using template helper functions

[shaun-nx]

This proposal aims to remove much of the business logic/logical conditions from our template files and move them into go functions. This aims to make the code more testable and easier to expand.

Example of current template file for custom listeners:

      {{ if not $s.CustomListeners }}
  listen 80{{ if $s.ProxyProtocol }} proxy_protocol{{ end }};
  {{ if not $s.DisableIPV6 }}listen [::]:80{{ if $s.ProxyProtocol }} proxy_protocol{{ end }};{{ end }}
      {{ else }}
      {{ if (gt $s.HTTPPort 0) }}
  listen {{ $s.HTTPPort }}{{ if $s.ProxyProtocol }} proxy_protocol{{ end }};
  {{ if not $s.DisableIPV6 }}listen [::]:{{ $s.HTTPPort }}{{ if $s.ProxyProtocol }} proxy_protocol{{ end }};{{ end }}
      {{ end }}
      {{ end }}

Example of template file for customer listeners after adding template helper function:

{{ makeListener $s.Listener $s.CustomListeners | printf }}

The code for makeListener will reside in a function in internal/configs/version1/template_helper.go

[github-actions]

Hi @shaun-nx thanks for reporting!

Be sure to check out the docs and the Contributing Guidelines while you wait for a human to take a look at this 🙂

Cheers!