rails bootstrap-sass assets compilation error - undefined variable alert-padding

Question

all roads point to bootstrap-sass

Referral chain:

• railscast-328 (twitter bootstrap basics) refers to
• http://www.sitepoint.com/twitter-bootstrap-less-and-sass-understanding-your-options-for-rails-3-1/ which refers to
• https://github.com/jlong/sass-bootstrap which in turn exclaims there is a new official port of bootstrap to sass at
• https://github.com/twbs/bootstrap-sass which is another one of the options in the twitter-bootstrap article

It is reported as an issue with the bootstrap-rails gem: https://github.com/anjlab/bootstrap-rails/issues/91

I believe I installed it correctly

The gems

gem 'sass-rails', '>= 3.2' # sass-rails needs to be higher than 3.2
gem 'bootstrap-sass', '~> 3.1.1'

are installed (tried outside and inside of assets group), application.css.scss contains

@import "bootstrap";

only.

but it gives me an error

When attempting bundle exec rake assets:precompile it gives this error:

rake aborted!
Undefined variable: "$alert-padding".
  (in /home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/bootstrap-sass-3.1.1.0/vendor/assets/stylesheets/bootstrap/_alerts.scss)
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/bootstrap-sass-3.1.1.0/vendor/assets/stylesheets/bootstrap/_alerts.scss:10
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/script/variable.rb:49:in `_perform'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/script/node.rb:40:in `perform'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:298:in `visit_prop'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:37:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:100:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `map'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:37:in `block in visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:320:in `visit_rule'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:37:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:100:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `map'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:53:in `visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:37:in `block in visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:128:in `visit_root'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/base.rb:37:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:100:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/visitors/perform.rb:7:in `visit'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/tree/root_node.rb:20:in `render'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/engine.rb:315:in `_render'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-3.2.7/lib/sass/engine.rb:262:in `render'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sass-rails-3.2.6/lib/sass/rails/template_handlers.rb:106:in `evaluate'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/tilt-1.3.7/lib/tilt/template.rb:77:in `render'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/context.rb:193:in `block in evaluate'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/context.rb:190:in `each'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/context.rb:190:in `evaluate'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/processed_asset.rb:16:in `initialize'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/base.rb:18:in `new'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/base.rb:18:in `block in build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:270:in `circular_call_protection'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/base.rb:14:in `build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/index.rb:93:in `block in build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/caching.rb:19:in `cache_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/index.rb:92:in `build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:169:in `find_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/index.rb:14:in `find_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/bundled_asset.rb:12:in `initialize'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/base.rb:22:in `new'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/base.rb:22:in `build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/index.rb:93:in `block in build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/caching.rb:19:in `cache_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/index.rb:92:in `build_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:169:in `find_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/index.rb:14:in `find_asset'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/static_compiler.rb:41:in `block in compile'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:219:in `block in each_logical_path'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:206:in `block (2 levels) in each_file'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:196:in `each'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:196:in `each_entry'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:204:in `block in each_file'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:203:in `each'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:203:in `each_file'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/sprockets-2.2.2/lib/sprockets/base.rb:217:in `each_logical_path'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/sprockets_overrides/static_compiler.rb:29:in `compile'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/tasks/assets.rake:108:in `internal_precompile'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/turbo-sprockets-rails3-0.3.11/lib/turbo-sprockets/tasks/assets.rake:115:in `block (3 levels) in <top (required)>'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
/home/joe/.rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/rake-10.0.4/lib/rake/application.

Answer 1

My specific problem turned out to be some code hiding in application.rb...

how I found it

I added puts config.assets.precompile.inspect to config/environments/production.rb and marvelled at the regex it output. Then I searched the codebase for "config.assets.precompile" and lo, in application.rb, there was:

config.assets.precompile << /(^[^_/]|/[^_])[^/]*$/
...
config.assets.precompile += ["*.js", "*.css", "jquery-migrate-rails.js"]

which was causing the problem. (I'm slightly puzzled as I've triple checked those regexes and they shouldn't be picking up _alerts.scss... but lets gloss over that and focus on the fact that removing those lines fixed it)

Maybe this will help someone else...