ruby on rails 3 - What is the purpose of config.assets.precompile?

Question

In Rails 3.1, you must whitelist files that you want included in asset precompilation. You must open up config/environments/production.rb and explicitly include assets you want precompiled:

config.assets.precompile += ['somestylesheet.css']

If you don't do this this and you run rake assets:precompile, your asset will not be copied to public/assets, and your app with raise an exception(therefore causing a 500 error in production) when an asset is not found.

Why is this necessary? Why aren't all assets automatically precompiled?

This current approach creates extra code and stress when deploying. Wouldn't it be easier to blacklist/exclude assets so things worked right out of the box? Anyone else share these feelings?

Answer 1

Most assets are automatically included in asset precompilation. According to the RoR Guide on the Asset Pipeline:

The default matcher for compiling files includes application.js, application.css and all files that do not end in js or css: [ /w+.(?!js|css).+/, /application.(css|js)$/ ]

You would use config.assets.precompile if you have additional assets to include:

config.assets.precompile += ['admin.js', 'admin.css', 'swfObject.js']

Or you could overwrite it.