https://blog.sandstorm.io/news/2014-07-25-sharelatex.html
Most of our existing apps are actually ports of existing open source Linux-based servers. Most were ported by Jason Paryani over the last month, which tells you how easy it is. This includes apps written in PHP, Python, Node, etc.
Note that the dev tools (and all the platform source code) are available to anyone. There are some WIP docs on the wiki:
https://github.com/sandstorm-io/sandstorm/wiki
It's probably actually harder to port _away_ from Sandstorm simply because you have to add a login system and other such features. Adding is a lot harder than removing. :)
Anyway, this is wonderful. One more question - web2py?
It's actually incredibly easy to move your data between Sandstorm hosts. Unlike, say, Google apps, Sandstorm apps are not tied to the hosting, so you can change hosts while still using exactly the same app. You can also run Sandstorm on your own machine if you want (it's open source).
Porting data from a Sandstorm version of an app to a non-Sandstorm version is also relatively easy. If you click the "download a backup" button, it's just a zip file that contains the app's database in whatever format it uses. But, how exactly to set up the app outside of Sandstorm depends entirely on the app.
Regarding web2py: I don't know much about it, but I assume it runs on Linux so it should work fine for writing a Sandstorm app...
Nice implementation.
Not really true. Sandstorm acts as a proxy in front of the apps and adds headers which identify the user. It takes very little code on the app side to read these headers and use them rather than use the app's own authentication.
That said, we do have some changes which we'll have to rebase from time to time. Eventually we hope that app developers will be interested in maintaining these changes themselves and explicitly targeting Sandstorm, but that is probably a ways away still. In the meantime, maintaining the edits doesn't seem to painful.