Which lightweight python web framework has applications and hot-deployed code

Question

I am used to PHP having applications. For example,

c:\xampp\htdocs\app1
c:\xampp\htdocs\app2

can be accessed as

localhost://app1/page.php
localhost://app2/page.php

Things to be noticed:

1. a directory placed inside the www-root directory maps directly with the URL
2. when a file/directory is added/removed/changed, the worker processes seamlessly reflect that change (new files are hot-deployed).

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I am on the lookout for a mature python web framework. Its for a web API which will be deployed for multiple clients, and each copy will diverge on customization. And our workflow has frequent interaction/revision cycles between us and our clients. Hence the "drag and drop" deployment is a must.

Which python framework enables this? I prefer a lightweight solution (which doesnt impose MVC, ORMs etc)

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fastcgi, cherrypy, and python

Answer 1

No mature python framework that I'm aware of allows you to map urls to python modules, and frankly, for good reason. You can do this with CGI, but it's definitely not the recommended way to deploy python apps. Setting that requirement aside, flask and bottle are both lightweight micro web-frameworks with similar approaches, both allow you to reload automatically when changes are detected (this is only wise during development).

Answer 2

There is no web framework in Python that I know of that lets you do that out of the box, but if you need it it's not to hard to add with a bit of convention over configuration.

Simply pick your web framework of choice in Python and then write a wrapper to the main application that walks a directory or set of directory and auto-registers routes from the modules inside of them. Have your modules do the same thing in their __init__.py files to the other files located with them. Then just set up your WSGI code to autoreload when the WSGI script is updated and your deployment during development simply becomes a two step process - add file then touch dev_app.wsgi. You could even add a real deployment option to this wrapper that walks a set up dev environment like this and generates hard-coded URL-to-function mappings for deployment.

However, all of this work isn't really necessary. Python is not PHP and the way you develop in one doesn't necessarily translate to the other well. If the client wants variable routes, use dynamic routes and give them (or you) an admin interface to control the mapping of content to URL. Use flat files, SQLite, a NoSQL datastore, or the ether to store these mappings and the content. Use a template engine like Jinja2, Mako, Cheetah or Genshi to maintain your general layout. Wrap this all up with an object oriented structure to make extending it easy (or use a functional paradigm if that comes more naturally to you). Or, drop the whole dynamic in production portion and generate flat HTML files a la Jekyll.

Answer 3

CherryPy is a mature web framework that redeploys automatically when changes are detected. The file structure - URL isn't there, but it is a lightweight framework that doesn't impose ORM, MVC, or even a templating engine.

Answer 4

If you are used to PHP, you might want to take a look at the Apache modules mod_python or mod_wsgi (and WSGI in general if you do web development -- which is the Pythonic way).

With those two modules, the Python interpreter gets started every time a request comes in (similar to PHP). Needless to say, this slows things down but you'll always get the result based on your newest code. Depending on your expected traffic numbers, this might or might not be okay for you.

BUT: If you decide to write your own framework, you most probably do not want to write a system that supports "hot-deploying". Even though the reload() command is built-in, it takes more than just that and will get you into a world full of pain.