Managing assets with Rails Assets
Up until recently, managing external CSS and JavaScript dependencies in Rails apps was a big pain. Solutions varied from just checking the latest downloaded version of a library into source control and forgetting about it to using Bower to manage dependencies.
Take a look at your vendor/assets directory. How old are the libraries there? How often do you remember to check for new versions? There could be some serious bugs discovered and fixed, maybe even security issues resolved.
Current approaches
One of the ideas of solving this problem is using the *-rails asset gems. They are often unofficially maintained gems that re-package the original library into a ruby gem. While we can't be sure they're up to date with official releases, we gain a powerful tool that lets us know when newer versions are available: bundle outdated.
Another way to manage assets is to use bower. It is a package manager built using nodejs that is the defacto standard in the front-end development world. Pretty much every library has a bower package, and they're often maintained along with the library. That said, bower is not without faults. First, the assets still need to be somehow added to the app's directory when it's deployed. There are two ways to do this: either fetch them on the development machine and add to source code, or add a hook to your deployment process to install dependencies on each deploy.
Enter Rails Assets
Rails Assets is a system designed to combine the two approaches described above into one that is the best of both worlds. From the outside, it acts as a gem server, with rubygems and bundler compatible APIs, so it fits the normal workflow for ruby development and can be used in a Gemfile. Under the hood, it fetches bower packages and automatically converts them into gems.
Adding assets using Rails Assets is really simple:
First, add https://rails-assets.org as a source in your Gemfile:
source 'https://rubygems.org'
source 'https://rails-assets.org'
Then, look up the package on the Rails Assets component list. Most libraries will already be there, but if you can't find the one you need, you should use the add component form to request it.
Finally, add the gem to the Gemfile, with the rails-assets- prefix:
gem "rails-assets-angular", "1.2.10"
Using this approach, you get the best of both worlds. The packages are easily kept up to date with bundle outdated, installing gems is already included in your deployment process, and the most recent version is available as soon as the bower package gets updated.