Error Page Assets

Generate your static error pages with the asset pipeline.

This gem lets you include Sprockets-generated CSS and JS files -- complete with cache-busting digests -- in public/404.html and friends. You can even use layouts. No monkeypatching, no Rails engines, no routing, just idiomatic asset pipeline code.

rake assets:precompile generates static files so your webserver will respond even when your application is down hard.

Installation

Add this line to your Gemfile:

gem 'error_page_assets'

Move your error pages into the asset pipeline

git mv public/404.html app/assets/html/404.html.erb
git mv public/422.html app/assets/html/422.html.erb
git mv public/500.html app/assets/html/500.html.erb

And tell the asset pipeline to compile your error pages. In config/application.rb:

config.assets.precompile += %w[404.html 422.html 500.html]

That's it!

Usage

Whenever assets are precompiled (i.e. during each deploy), your error pages will be generated and saved in /public.

$ rails assets:precompile
copy public/assets/404-1c763a81450.html to public/404.html

Rails Helpers

Here's an example of using Rails helpers:

old:
  <link href="/css/application.css" media="all" rel="stylesheet"/>
  <script src="/js/application.js"></script>
new:
  <%= stylesheet_link_tag 'application', media: 'all', digest: true %>
  <%= javascript_include_tag "application" %>

Layouts

The Asset pipeline knows how to include stylesheets in your html, but it doesn't know how to render layouts. If you'd like your static error pages to use layouts too, use the render anywhere gem.

Roadmap

• Do we still need to use digest:true?
• Use an initializer to automatically add error pages to the sprockets config?
• Rails generator to move your error pages?
• I haven't bothered with I18n.available_locales/404.es.html. If you'd like localization, please file an issue.

Alternatives

• Inspired by: http://icelab.com.au/articles/precompiled-rails-static-404-and-500-pages/
• Rails Engine: https://github.com/marcusg/dynamic_error_pages
• Dynamic Route: https://github.com/eric1234/better_exception_app

License

Pain-free MIT.

Contributing

To make this gem less imperfect, please submit your issues and patches on GitHub.