[Web-SIG] A Python Web Application Package and Format

[Eric Larson]

Hi, 

On Apr 10, 2011, at 10:29 PM, Alice Bevan–McGregor wrote:

> However, the package format I describe in that gist does include the source for the dependencies as "snapshotted" during bundling.  If your application is working in development, after snapshotting it /will/ work on sandbox or production deployments.

I wanted to chime in on this one aspect b/c I think the concept is somewhat flawed. If your application is working in development and "snapshot" the dependencies that is no guarantee that things will work in production. The only way to say that snapshot or bundle is guaranteed to work is if you snapshot the entire system and make it available as a production system. 

Using a real world example, say you develop your application on OS X and you deploy on Ubuntu 8.04 LTS. Right away you are dealing with two different operating systems with entirely different system calls. If you use something like lxml and simplejson, you have no choice but to repackage or install from source on the production server. While it is fair to say that generally you could avoid packages that don't use C, both lxml and simplejson are rather obvious choices for web development. You could use the json module and ElementTree, but if you want more speed (and who doesn't like to go fast!), lxml and simplejson are both better options. 

It sounds like Ian doesn't want to have any build steps which I think is a bad mantra. A build step lets you prepare things for deployment. A deployment package is different than a development package and mixing the two by forcing builds on the server or seems like asking for trouble. I'm not saying this is what you (Alice) are suggesting, but rather pointing out that as a model, depending on virtualenv + pip's bundling capabilities seems slightly flawed. 

Personally, and I don't expect folks to take my opinions very seriously b/c I haven't offered any code, what I'd like to see is a simple format that helps install and uninstall web applications. I think it should offer hooks for running tests, learning basic status and allow simple configuration for typical sysadmin needs (logging via syslog, process management, nagios checks, etc.). Instead of focusing on what format that should take in terms of packages, it seems more effective to spend time defining a standard means of managing WSGI apps and piggyback or plain old copy some format like RPMs or dpkg. 

Just my .02. Again, I haven't offered code, so feel free to ignore me. But I do hope that if there are others that suspect this model of putting source on the server is a problem pipe up. If I were to add a requirement it would be that Python web applications help system administrators become more effective. That means finding consistent ways of deploying apps that plays well with other languages / platforms. After all, keeping a C compiler on a public server is rarely a good idea.

Eric

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