[LRUG] Rails 4 asset deployment woes

[Jonathan del Strother]

On 15 July 2013 12:45, James Coglan <jcoglan at gmail.com> wrote:
> I'm struggling with getting asset deployment to work after upgrading a few
> of our apps to Rails 4. I have two main problems:
>
> * We cannot reference images/fonts from stylesheets
> * Our CSS/JS is no longer being minified in production
>
> The first one is because Rails no longer generates unversioned filenames in
> public/assets, so you need to have
>
>     body {
>       background: url(/assets/cat-abc123def456.jpg);
>     }
>
> in your stylesheet rather than
>
>     body {
>       background: url(/assets/cat.jpg);
>     }
>
> Of course, the latter works in development but not in production after
> precompiling the assets. So, we need to know how to get those version
> numbers into the CSS, since Rails does not rewrite these references by
> default while precompiling assets.
>
> Second, our CSS is not being minified, and we have no idea why. If you clone
> https://github.com/jcoglan/rails_assets, and run:
>
>     $ bundle exec rake assets:precompile
>
> then it does not minify the code in public/assets, which we assumed was
> because config/environments/development.rb sets config.assets.debug = true.
> If you compile in production:
>
>     $ RAILS_ENV=production bundle exec rake assets:precompile
>
> then it does minify the CSS. So, we figured there must be a config
> difference and that would explain why our code is not being minified in our
> production apps that have been upgraded from Rails 3 to 4. So, I deleted all
> the code from config/environments/{development,production}.rb and it still
> does the same thing: no minification in development mode, and minified code
> in production. So it doesn't seem like a config thing -- is this difference
> baked in Rails? What am I doing wrong? Why would our production apps not be
> minifying their CSS?

Your stylesheets should be using the asset helpers to generate their
paths.  eg -

    body {
      background: image-url("cat.jpg");
    }

should get automatically expanded to the full version-stamped path.
See http://guides.rubyonrails.org/asset_pipeline.html#css-and-sass for
more.