buildout recipe for installing Selenium RC

This weekend at the Plone Naples Sprint one of the things I worked on was a buildout to download and install Selenium RC. It is now available from PYPI under the name collective.recipe.seleniumrc For some reason the Selenium RC distribution zip file contains version numbers on each subdirectory so this meant I couldn't just use one of the existing download scripts. But I didn't want to re-invent the download recipe wheel, so I decided to base this recipe on a well-written existing download recipe, hexagonit.recipe.download. I asked on IRC if the author was present at the sprint and ironically enough he was sitting in the same room as me only two rows away ;) With some simple changes to his recipe I was able to derive collective.recipe.seleniumrc from it and gain features like download caching and md5 file hash verification. Along the way I learned that if you want your buildout recipe to be derived by others you should make it a new-style Python class so that super() works. Also that it helps to factor your install() method into submethods for overriding. The changes I made to hexagonit.recipe.download were cleaned up and integrated into a 1.1.0 release that we made yesterday, along with the 0.1 release of collective.recipe.seleniumrc If you want to try out the Selenium RC recipe just create a simple buildout.cfg:

[buildout]
parts=seleniumrc

[seleniumrc]
recipe=collective.recipe.seleniumrc

After you are finished running this buildout you will get a nice wrapper script in your bin folder named by the part, in this case seleniumrc. Happy testing!

Buildouts

How annoying is it to deploy an application? How prone to errors due to the sheer repetitiveness of the common deployment? Buildouts to the rescue! What is a buildout? It's a automated set of steps for creating a deployment environment. This could mean one little application, or it could be several and they would setup to talk to each other. zc.buildout came out sometime last year and I've had my eye on it since then. I'd wanted to do Jim Fulton's tutorial on it at Pycon this year but wasn't able to schedule it in! I've had the opportunity in the last couple weeks to start using a bit more and I really appreciate the conceptual basis for this framework. The idea that a deployment consists of parts is something you can explain to anyone, for example. A web app needs a webserver, some kind of storage backend, the application code and some preexisting data: parts=apache mysql application-data application or full Zope-based solution: parts=apache zope zeo plone mywebsite mywebsite-data What I've noticed so far is that for a particular application even though someone might have already wrote a recipe for it actually getting it configured the way you want usually requires extending that recipe slightly. If the recipe was written with this in mind its easy enough to extend. I did have a bit of problems extending some of the plone.recipe.* recipes because they were old style classes and so I couldn't use super() to extend the default behaviour. Easy to fix though!

ZOPE / ZEO buildout recipe with multiple database support

I created a branch that adds the ability to configure multiple databases in your configuration files which I needed for a project, so this should be a fairly decent example for anyone else needed to something similar. See the jbb666-multiple-dbs branch for zeo instance and the corresponding branch for the zope recipe. For a lot of the Zope recipes the config knobs that need to be exposed will be determined and you won't need to touch the underlying recipe except in well exceptional circumstances.