Web Applications – Deployment and Dependencies

Off top of my head...

• access proprietary hardware that exports its I/O by other means than a file. Be that scientific equipment, industrial machinery, or plain CD recorder and a digitizer tablet with tilt support.
• only HTTP and a small family of other protocols. You can't create sockets as you wish, transferring whatever binary data you desire. That vastly limits connectivity with other systems and services.
• No sane developer will create graphics-intensive game in Javascript. Broadband is not nearly comparable to DVD/HDD throughputs often needed. Support for 3D in Canvas is vastly inferior to what you get with game engines. No way to support joystick, multiple simultaneous keypresses, the open nature makes cheating easy. But primarily, the performance drop is not acceptable.
• Heavy sandboxing. You won't get stuff that deeply integrates into the OS. Screenshots, antivirus, virtual drives, background tasks a'la system tray, administrative tasks etc.
• can't be mission-critical. Depending on broadband at all times to run their basic software is not the preferred way most companies like to run.

This sounds like an effective approach; I like the creativity. Since you asked for comments, I will offer a few:

1) While puppet is a very powerful tool, it seems like a bit of overkill for just directory creation and permissions. A simple bash script might do the trick in as many lines as Puppet, with no Puppet executable dependency.

2) Consider using Puppet to do your deployment too: PuppetLabs provides a manifest to check out of a git repository. Then you can run it periodically, or on some other form of trigger. This obviously would invert the directionality of your deployment, turning it from a "push" model to a "pull" model. It can have advantages, including simplicity.

3) A more advanced usage of Puppet would have you set up your entire production environment from scratch, including installing your app. This would create a fully automated instance of your app, making virtualized instances easy and portable, and causing horizontal scaling to be simple.