Non-digest assets in Rails

What is it?

In Rails starting from version 4, there is no way to by default compile both digest and non-digest assets. This is problematic if you also need to refer to assets from outside your Rails application. This gem solves the problem with the minimum possible effort.

How do I install it?

Just put it in your Gemfile

gem "non-digest-assets"

If you want to generate non-digest assets for only certain files, you can configure a list of asset selectors like this:

# config/initializers/non_digest_assets.rb

NonDigestAssets.asset_selectors += [/tinymce\/.*/, "image.png"]

Be sure to give either a regex that will match the right assets or the logical path of the asset in question.

Note that the logical path is what you would provide to asset_url, so for an image at RAILS_ROOT/assets/images/foo.png the logical path is foo.png

But shouldn't I always use the Rails asset helpers anyway?

Yes. But there are some obvious cases where you can't do this:

• Third party libraries in vendor/assets that need to include e.g. css / images
• In a static error page, e.g. a 404 page or a 500 page
• Referencing the assets from outside your rails application

What about other solutions?

sprockets-redirect uses a rack middleware to 302 redirect to the digest asset. This is terrible for performance because it requires 2 HTTP requests, and it also hits your ruby stack. An asset request should be handled by your webserver (e.g. nginx) because that's what it's good at.

This rake task will solve this problem, but requires an extra rake task. It won't work by default with things like capistrano / heroku. And it requires you to manage the code in your app.

Why do I need digest assets at all?

Digests are used for cache busting. Remember that if you use the non-digest assets and serve them with far-future expires headers, you will cause problems with cached assets if the contents ever need to change. You must bear this in mind when using non-digest assets.

Why is this not the default or a config option in Rails?

The sprockets-rails developers do not want to support it. Read the discussion here

Which versions of Ruby and Rails are supported?

This gem is tested with Rails 6.0, 6.1 and 7.0 and targets Ruby 2.7 and up.

Who wrote this?

This gem was created under a different name by Alex Speller and is currently maintained by Matijs van Zuijlen.

Can I contribute?

Certainly. See CONTRIBUTING.md for contribution guidelines.