Building Clouds

I’ve spent this year building networks using Amazon Web Servicesand teaching people how to do it. So I’d like to share the code that I’ve used as teaching examples and as seeds for the creation of some pretty cool environments. AWS PY was my first published attempt at interacting with AWS in python & Puppet to instantiate, provision and control EC2 instances, as well as the seed for an incredibly cool project at the start of this year....

Provision EC2 instance using boto

Sam Newman recently published a very interesting blog entry on using fabric to apply puppet scripts on remote machines. He left the provision_using_boto() method as an exercise to the reader. That just sounded tempting enough to be a challenge since I hadn't gotten around to looking at boto. You can find the result of my attempt on GitHub. To be precise aws.py implements the provisioning using boto and fabfile.py drives fabric and puppet....

AWS CloudFront invalidation

It is now possible to invalidate objects (files) in AWS CloudFront distributions. Handy when someone, like me, occasionally publishes files with the wrong content type. Here is how I implement this invalidation in python....

PostgreSQL & Python on Mac

I've been playing with Django & MySQL for a while but for my next project I wanted to integrate it with a PostgreSQL database. Everything went well until I wanted to install Psycopg as my python adapter to PostgreSQL. After a bit of blundering about here's what it eventually took: Download and install PostgreSQL one-click installer from http://www.postgresql.org/download/macosx. Remember to read the README file before actually running the installer. Download the psycopg2 source from http://initd....

Django RESTful resources

Last year I blogged about a neat trick in Django to have multiple views per HTTP verb. Since then I’ve been playing with RESTful applications and decided to see if there was a nicer way to expose “resources” in Django. The following is what I’ve come up with so far. Listing: router.py from django.http import Http404, HttpResponseNotAllowed def get_handler_method(request_handler, http_method): try: handler_method = getattr(request_handler, http_method.lower()) if callable(handler_method): return handler_method except AttributeError: pass class Resource: http_methods = ['GET', 'POST', 'HEAD', 'PUT', 'DELETE', 'OPTIONS', 'TRACE'] @classmethod def dispatch(cls, request, *args, **kwargs): request_handler = cls() if request....

From Java to Groovy

Recently I’ve been playing with some old Java Swing applications and I found myself wishing that I could replace all the anonymous inner-classes with some clean Groovy closures. The job of converting a java source file to a groovy source file is pretty simple and eminently scriptable. Here’s my take on a python script to do just that: from optparse import OptionParser from subprocess import Popen, PIPE import os def rename(src, dest, use_svn): if use_svn: output = Popen(['svn', 'rename', src, dest], stdout=PIPE)....

Django and multiple methods per url pattern

HTTP verbs are not used to determine the route to a view method by deliberate design in Django. Sometimes I find it useful to be able to specify different methods for the same url pattern - one per HTTP verb. The Django book contains an interesting example of how this can be done using the django.conf.urls.defaults.url method to separate POST from GET processing. I’ve extended the example to provide handling to cover the standard HTTP verbs....

Thumper - web application performance testing

Over the years I've been involved with writing a number of web applications. Some I am proud of, some I never want to see again. During each project, testing of the application's performance, stability under load, and regression testing of user journeys always comes up. There are a number of great bits of hardware (eg. Avalanche), and software (eg. Grinder) that help you test applications. I've even had a fun time using a room full of Grinder clients to test web services for a client - a great way to run a denial of service attack :-)...