Rails: application.css not in asset pipeline

Ok, first thing.

Do you have config.serve_static_files = true set in your production.rb file under config/environment folder.

Since we run behind NGINX, in our case it looks like config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?

Second thing. Did you do rails assets:precompile before the uploading it to the server?

And the third thing is. Have you tried calling your file application.css.scss, and redoing the rails assets:precompile?

Last, and not least thing. How does your application.scss file look like?

Did you remove all those *= and used @import instead for Bootstrap

It is nicely described in the documentation:

Import Bootstrap styles in app/assets/stylesheets/application.scss:

// Custom bootstrap variables must be set or imported before bootstrap. @import "bootstrap";

And then it says:

Make sure the file has .scss extension (or .sass for Sass syntax). If you have just generated a new Rails app, it may come with a .css file instead. If this file exists, it will be served instead of Sass, so rename it:

$ mv app/assets/stylesheets/application.css app/assets/stylesheets/application.scss Then, remove all the *= require and *= require_tree statements from the Sass file. Instead, use @import to import Sass files.

Do not use *= require in Sass or your other stylesheets will not be able to access the Bootstrap mixins and variables.

Read more here

in my case, I forgot to install yarn command in my server.

so, please install "yarn" before running rails server. otherwise "assets:precompile" will do nothing and give no warning.

To give more clarity to mutantkeyboard's answer

I had this issue when deploying a Rails application as a docker image that would run in a docker container without a web server like Nginx.

Here's how I got it fixed:

This issue is primary caused in production when you do not want to serve your static files from the /public folder using a web server like Nginx or Apache.

To serve files your static files from the /public folder without using a web server like Nginx or Apache, do the following:

Ensure you precompile your assets using:

bundle exec rails assets:precompile

OR

rails assets:precompile

This will compile your assets into the /public folder

Next, in your config/environments/production.rb file, add the following:

Instead of this:

config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?

Use this:

config.public_file_server.enabled = true

This allows rails to serve the static files instead of a web server

Note: For improved performance it's best to serve the static files using a Web server like Apache or Nginx.

That's all.

I hope this helps