title: Separating Django installed apps between Development vs Production
body: <p>I have 3 settings files:</p>
  
  <ul>
  <li>base.py (shared)   </li>
  <li>development.py   </li>
  <li>production.py</li>
  </ul>
  
  <p>base.py has:  </p>
  
  <pre><code>INSTALLED_APPS = (
  
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes'
      ...
  </code></pre>
  
  <p>but I have some apps that I only want in my development environment, for example, <code>debug-toolbar</code>.  </p>
  
  <p>I tried this in development.py:  </p>
  
  <pre><code>INSTALLED_APPS += (
      'debug_toolbar',
  )
  </code></pre>
  
  <p>But get the error: <code>NameError: name 'INSTALLED_APPS' is not defined</code></p>
  
  <p>The settings files are connected like this:</p>
  
  <p><code>__init__.py</code></p>
  
  <pre><code>from .base import *
  
  try:
      from .production import *
  except:
      from .development import *
  </code></pre>
  
  <p>How can I differentiate the installed apps between my production/development environment?</p>