More flexibility in email alert template (MIME, etc)

[Vegard Vesterheim]

Alert mail sent by NAV is MIME-type text/plain. It would be useful to also allow HTML-formatted mail, preferably as an alternative to text-formatting, aka multipart/alternative.

One possibility is to consider the mail template as a RFC822-formatted message, containing both headers and body, separated by a blank line. The Django templating system makes this a bit cumbersome, because the handling of white-space and linefeeds is geared towards HTML-output.

In the current implementation, the Subject header must be the first line. A simplistic solution to the more general approach above, could therefore be to allow another header line, namely "Content-type" as the *second* line in the template.

[Vegard Vesterheim (vegard-vesterheim)]

root@nav:/usr/share/pyshared/nav/alertengine/dispatchers# diff -u email_dispatcher.py~ email_dispatcher.py
--- email_dispatcher.py~ 2016-06-30 10:46:58.000000000 +0200
+++ email_dispatcher.py 2016-09-12 14:36:30.390898104 +0200
@@ -39,15 +39,24 @@
         # Remove the subject line
         message = '\n'.join(message.splitlines()[1:])

+ content_type='text/plain'
+ # Look for Content-type in next line
+ template_content_type = message.splitlines(1)[0].lstrip('Content-Type:').strip()
+ if template_content_type:
+ content_type = template_content_type
+ # Remove the Content-type line
+ message = '\n'.join(message.splitlines()[1:])
+
         headers = {
             'X-NAV-alert-netbox': alert.netbox,
             'X-NAV-alert-device': alert.device,
             'X-NAV-alert-subsystem': alert.source,
+ 'Content-type': content_type,
         }

         try:
             if not address.DEBUG_MODE:
- email = EmailMessage(subject=subject, body=message,
+ email = EmailMessage(subject=subject, body=message, headers=headers,
                                      to=[address.address])
                 email.send(fail_silently=False)
             else:

[Vegard Vesterheim (vegard-vesterheim)]

This will break old templates!

How should we preserve backwards compatibility?

[Vegard Vesterheim (vegard-vesterheim)]

Idea from John-Magne: How about reusing the HTML-templates from the web-gui in the email templates