How do I allow clients to create dynamic databases and connections as a multitenant database setup with Django on Appengine?

Question

Our current set up has Django hosted on Google's appengine with a MySQL database on Google's Cloud SQL.

The users (clients) are typically small businesses who we give a subdomain to for a multi-tenant database structure (1 database for each client).

As for determining which request should hit up which database, there is an existing middleware which strips the request path to get the subdomain and thus returning the correlated database alias defined in settings.py

from django.conf import settings
import threading
currentCompanyConnection = threading.local()

class DatabaseMiddleware(object): 
    def process_request(self, request): 
        url = request.build_absolute_uri()
        if url.find("http://") < 0:
            company = url.split("https://")[1].split(".")[0]
        else:
            company = url.split("http://")[1].split(".")[0]
        global currentCompanyConnection
        if company in settings.DATABASES:
            currentCompanyConnection.company = company
        else:
            currentCompanyConnection.company = 'default'
        request.currentCompany = str(currentCompanyConnection.company)
        return None

class DBRouter(object): 

    def read_and_write(self, model, **hints): 
        return currentCompanyConnection.company

    db_for_read  = read_and_write 
    db_for_write = read_and_write

However, to allow our web application the functionality of a freemium self-service, a new database must be generated on the fly and imported into Django's settings.py dynamically for each user who sign up.

The last part is something I can't seem to figure out, since each time I change the settings.py, I must deploy it to appengine again. Aside from that, I'm not sure how to create a new database with pre-defined tables in Google's Cloud SQL from our web application.

Thanks for your help! I love resolving challenges from work, but this is something I simply haven't done before =O

score 1 · Answer 1 · answered Mar 22 '13 at 03:05

You can't modify your source files once deployed. You can modify stuff in the blobstore or datastore.

I'd recommend storing the settings as structured data in the datastore, then have your settings.py read the data from the datastore and store them as python objects in settings.py that are accessible from other code. This should allow you to configure django to connect to multiple databases.

I'm not too familiar with CloudSQL, but I think you may still have a challenge of starting multiple CloudSQL instances and routing the appropriate traffic to the appropriate instances.

Thanks for the advice, I appreciate it! Storing dynamic database data in settings.py may be appropriate for configuring django. — AndyHsiung, Apr 11 '13 at 22:10

How do I allow clients to create dynamic databases and connections as a multitenant database setup with Django on Appengine?

1 Answers1