How to use Django to get the name for the host server?

Just add to @Tobu's answer. If you have a request object, and you would like to know the protocol (i.e. http / https), you can use request.scheme (as suggested by @RyneEverett's comment).

Alternatively, you can do (original answer below):

if request.is_secure():
    protocol = 'https'
else:
    protocol = 'http'

Because is_secure() returns True if request was made with HTTPS.

I generally put something like this in settings.py:

import socket

try:
    HOSTNAME = socket.gethostname()
except:
    HOSTNAME = 'localhost'

If you have a request (e.g., this is inside a view), you can look at request.get_host() which gets you a complete locname (host and port), taking into account reverse proxy headers if any. If you don't have a request, you should configure the hostname somewhere in your settings. Just looking at the system hostname can be ambiguous in a lot of cases, virtual hosts being the most common.