Question

I have a Django application that I would like to deploy to the desktop. I have read a little on this and see that one way is to use freeze. I have used this with varying success in the past for Python applications, but am not convinced it is the best approach for a Django application.

My questions are: what are some successful methods you have used for deploying Django applications? Is there a de facto standard method? Have you hit any dead ends? I need a cross platform solution.

Answer 1

I did this a couple years ago for a Django app running as a local daemon. It was launched by Twisted and wrapped by py2app for Mac and py2exe for Windows. There was both a browser as well as an Air front-end hitting it. It worked pretty well for the most part but I didn’t get to deploy it out in the wild because the larger project got postponed. It’s been a while and I’m a bit rusty on the details, but here are a few tips:

• IIRC, the most problematic thing was Python loading C extensions. I had an Intel assembler module written with C “asm” commands that I needed to load to get low-level system data. That took a while to get working across both platforms. If you can, try to avoid C extensions.

• You’ll definitely need an installer. Most likely the app will end up running in the background, so you’ll need to mark it as a Windows service, Unix daemon, or Mac launchd application.

• In your installer you’ll want to provide a way to locate a free local TCP port. You may have to write a little stub routine that the installer runs or use the installer’s built-in scripting facility to find a port that hasn’t been taken and save it to a config file. You then load the config file inside your settings.py and whatever front-end you’re going to deploy. That’s the shared port. Or you could just pick a random number and hope no other service on the desktop steps on your toes 🙂

• If your front-end and back-end are separate apps then you’ll need to design an API for them to talk to each other. Make sure you provide a flag to return the data in both raw and human-readable form. It really helps in debugging.

• If you want Django to be able to send notifications to the user, you’ll want to integrate with something like Growl or get Python for Windows extensions so you can bring up toaster pop-up notifications.

• You’ll probably want to stick with SQLite for database in which case you’ll want to make sure you use semaphores to tackle multiple requests vying for the database (or any other shared resource). If your app is accessed via a browser users can have multiple windows open and hit the app at the same time. If using a custom front-end (native, Air, etc…) then you can control how many instances are running at a given time so it won’t be as much of an issue.

• You’ll also want some sort of access to local system logging facilities since the app will be running in the background and make sure you trap all your exceptions and route it into the syslog. A big hassle was debugging Windows service startup issues. It would have been impossible without system logging.

• Be careful about hardcoded paths if you want to stay cross-platform. You may have to rely on the installer to write a config file entry with the actual installation path which you’ll have to load up at startup.

• Test actual deployment especially across a variety of firewalls. Some of the desktop firewalls get pretty aggressive about blocking access to network services that accept incoming requests.

That’s all I can think of. Hope it helps.