Copy&Waste

Using Django's Template system for network configs

I wrote hatch a few years ago to make cookie cutter network config templates. One thing I've wanted to implement for a while is a DSL for use in hatch. I've experimented with jscc and more recently with peg.js. While writing grammar for peg.js I said to myself "it would be great if I could used Django's template system and filters without re-inventing the wheel."

So I started experimenting and found out its pretty easy to do. A little more tinkering and I could possibly replace hatch's mechanics with Django's builtin template, tag, and filter code.

#!/usr/bin/python
from django.conf import settings
from django import template
settings.configure(DEBUG=True, TEMPLATE_DEBUG=True)
#https://github.com/django/django/blob/master/django/template/__init__.py

s = u'conf t\n ip address {{ip_address}} {{subnet_mask}} \n end \n write'
t = template.Template(s)
c = template.Context({'ip_address': '192.168.1.1','subnet_mask':'255.255.255.0'})
rendered = t.render(c)
print rendered

print "----------------------------------"

s = u'conf t\n ip address 10.{{site_code}}.1.1 {{subnet_mask}} \n end \n write'
t = template.Template(s)
c = template.Context({'site_code': '66','subnet_mask':'255.255.255.0'})
rendered = t.render(c)
print rendered


print "----------------------------------"

s = u'conf t\n {% if site_code == 66 %}snmp-server location Sydney{% endif%}'
t = template.Template(s)
c = template.Context({'site_code': 66})
rendered = t.render(c)
print rendered

akonkol@dev:~/Code/messy$ ./temp_hack.py
conf t
 ip address 192.168.1.1 255.255.255.0
 end
 write
----------------------------------
conf t
 ip address 10.66.1.1 255.255.255.0
 end
 write
----------------------------------
conf t
 snmp-server location Sydney