Question

My app serves multiple domains which I understand should be done by namespaces which I’m researching. Since multiple domains should have multiple analytics ID:s I get the analytics ID from the code but I want to make it even more configurable:

    if os.environ.get('HTTP_HOST').endswith('.br') \
        or os.environ['SERVER_NAME'].endswith('.br'):
        data[u'analytics'] = 'UA-637933-12'
else:
        data[u'analytics'] = 'UA-637933-18'

    self.response.out.write(template.render(os.path.join(os.path.dirname(__file__),
                            'templates', name + '.html'), data))

The above sets analytics ID to ..-12 if it’s my brazilian domain and to the other ID …-18 if it is my dot com. But this is only for 2 domains and it’s not easiliy generalizable. How can I achieve this function in a more scientific and scalable way so that it becomes easy to add my application to a domain without manually adding the domain to my application?

I suppose namespaces is the way to go here since the domains are google apps domains but I don’t understand how to use namespaces:

def namespace_manager_default_namespace_for_request():
  """Determine which namespace is to be used for a request.

  The value of _NAMESPACE_PICKER has the following effects:

  If _USE_SERVER_NAME, we read server name
  foo.guestbook-isv.appspot.com and set the namespace.

  If _USE_GOOGLE_APPS_DOMAIN, we allow the namespace manager to infer
  the namespace from the request.

  If _USE_COOKIE, then the ISV might have a gateway page that sets a
  cookie called 'namespace', and we set the namespace to the cookie's value
  """
  name = None

  if _NAMESPACE_PICKER == _USE_SERVER_NAME:
    name = os.environ['SERVER_NAME']
  elif _NAMESPACE_PICKER == _USE_GOOGLE_APPS_DOMAIN:
    name = namespace_manager.google_apps_namespace()
  elif _NAMESPACE_PICKER == _USE_COOKIE:
    cookies = os.environ.get('HTTP_COOKIE', None)
    if cookies:
      name = Cookie.BaseCookie(cookies).get('namespace')

  return name

I suppose I should use the namespace manager, get the namespace and set the analytics ID according to the namespace but how?

Thank you

Answer 1

The simplest way to do this is with a Python dict:

analytics_ids = {
  'mydomain.br': 'UA-637933-12',
  'mydomain.com': 'UA-637933-18',
}

data['analytics'] = analytics_ids[self.request.host]

If you have other per-domain stats, you may want to make each dictionary entry a tuple, a nested dict, or a configuration object of some sort, then fetch and store it against the current request for easy reference.

If you want to be able to reconfigure this at runtime, you could use a datastore model, but that will impose extra latency on requests that need to fetch it; it seems likely to me that redeploying each time you add a domain isn’t likely to be a problem in your case.

Namespaces are tangential to what you’re doing. They’re a good way to divide up the rest of your data between different domains, but they’re not useful for dividing up configuration data.