Bundler-like DSL + rake tasks for Bower on Rails
Ruby CSS
Latest commit 30c6697 Nov 28, 2016 @SergeyKishenin SergeyKishenin committed on GitHub Merge pull request #209 from rebagliatte/readme-update
Add instructions on how to install dev_dependencies



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Bower support for Rails projects. Dependency file is bower.json in Rails root dir or Bowerfile if you use DSL. Check out changelog for the latest changes and releases.


NOTE: If you install node via package manager with sudo apt-get install nodejs you'll also need to install nodejs-legacy with sudo apt-get install nodejs-legacy. See #91


in Gemfile

  gem "bower-rails", "~> 0.11.0"

JSON configuration

Bower-rails now supports the standard bower package format out-of-the-box. Simply place your bower.json file inside the Rails root directory to start. Using the standard format will default all bower components to be installed under the vendor directory.

To install dependencies into both lib and vendor directories, run the initializer to generate a custom bower.json:

  rails g bower_rails:initialize json

This will generate a config/initializers/bower_rails.rb config file and a special bower.json that combines two standard bower packages into one. Simply specify your dependencies under each folder name to install them into the corresponding directories.

example bower.json file

   "lib": {
    "name": "bower-rails generated lib assets",
    "dependencies": {
      "threex": "git@github.com:rharriso/threex.git",
      "gsvpano.js": "https://github.com/rharriso/GSVPano.js/blob/master/src/GSVPano.js"
  "vendor": {
    "name": "bower-rails generated vendor assets",
    "dependencies": {
      "three.js": "https://raw.github.com/mrdoob/three.js/master/build/three.js"

Include in Asset Pipeline

// Bower packages
//= require d3/d3
//= require underscore/underscore

Ruby DSL configuration

The Ruby DSL configuration is a Bowerfile at the project's root with DSL syntax similar to Bundler.

Run the initializer to generate a sample Bowerfile inside the Rails root and a config/initializers/bower_rails.rb config file:

  rails g bower_rails:initialize

Example Bowerfile

By default assets are put to ./vendor/assets/bower_components directory:

# Puts to ./vendor/assets/bower_components
asset "backbone"
asset "moment", "2.0.0" # get exactly version 2.0.0
asset "secret_styles", "git@github.com:initech/secret_styles" # get from a git repo

# get from a git repo using the tag 1.0.0
asset "secret_logic", "1.0.0", git: "git@github.com:initech/secret_logic"

# get from a github repo
asset "secret_logic", "1.0.0", github: "initech/secret_logic"

# get a specific revision from a git endpoint
asset "secret_logic", github: "initech/secret_logic", ref: '0adff'

# get a single file
asset "three.js", "https://raw.github.com/mrdoob/three.js/master/build/three.js"

But the default value can be overridden by assets_path method:

assets_path "assets/my_javascripts"

# Puts to ./vendor/assets/my_javascripts/bower_components
asset "backbone"
asset "moment"

The assets_path method can be overridden by an option in a group call:

assets_path "assets/javascript"

# Puts files under ./vendor/assets/js/bower_components
group :vendor, :assets_path => "assets/js"  do
  asset "jquery"            # Defaults to 'latest'
  asset "backbone", "1.1.1"

# Puts files under ./lib/assets/javascript/bower_components
group :lib do
  asset "jquery"
  asset "backbone", "1.1.1"

NOTE: Available groups are :lib and :vendor. Others are not allowed according to the Rails convention. NOTE: All the assets should be stored in /assets subdirectory so putting it under ./vendor/js directory is unavailable

You can extend main directive to include some missing files using main_files option as parameter or in a block:

# via argument
asset "moment", "2.10.1", main_files: ["./locale/en-gb.js"]

# or in block
asset "moment", "2.10.1" do
  main_files [

And finally, you can specify the assets to be in the devDependencies block:

asset "backbone", "1.1.1"

# Adds jasmine-sinon and jasmine-matchers to devDependencies
dependency_group :dev_dependencies  do
  asset "jasmine-sinon"            # Defaults to 'latest'
  asset "jasmine-matchers"         # Defaults to 'latest'

# Explicit dependency group notation ( not neccessary )
dependency_group :dependencies  do
  asset "emberjs"                  # Defaults to 'latest'

results in the following bower.json file:

  "name": "dsl-generated-dependencies",
  "dependencies": {
    "backbone": "1.1.1",
    "angular": "1.2.18",
  "devDependencies": {
    "jasmine-sinon": "latest",
    "jasmine-matchers": "latest"


  • Available dependency groups are :dependencies (default) and :dev_dependencies. Others are not allowed according to the Rails convention.
  • In order to install assets on the :dev_dependencies group please run RAILS_ENV=development rake bower:install.

Bower Resolutions

To specify a bower resolution use resolution DSL method in your Bowerfile:

resolution "angular", "1.2.22"

That will produce bower.json like:

  "name" : "dsl-generated-dependencies",
  "dependencies": {
    "angular": "1.2.22"
  "resolutions": {
    "angular": "1.2.22"


Change options in your config/initializers/bower_rails.rb:

BowerRails.configure do |bower_rails|
  # Tell bower-rails what path should be considered as root. Defaults to Dir.pwd
  bower_rails.root_path = Dir.pwd

  # Invokes rake bower:install before precompilation. Defaults to false
  bower_rails.install_before_precompile = true

  # Invokes rake bower:resolve before precompilation. Defaults to false
  bower_rails.resolve_before_precompile = true

  # Invokes rake bower:clean before precompilation. Defaults to false
  bower_rails.clean_before_precompile = true

  # Excludes specific bower components from clean. Defaults to nil
  bower_rails.exclude_from_clean = ['moment']

  # Invokes rake bower:install:deployment instead of rake bower:install. Defaults to false
  bower_rails.use_bower_install_deployment = true

  # rake bower:install will search for gem dependencies and in each gem it will search for Bowerfile
  # and then concatenate all Bowerfile for evaluation
  bower_rails.use_gem_deps_for_bowerfile = true

  # Passes the -F option to rake bower:install or rake bower:install:deployment. Defaults to false.
  bower_rails.force_install = true

  # Change the default directory name
  bower_rails.bower_components_directory = 'bower_components'

If you are using Rails version < 4.0.0 then you are to require bower_rails.rb initializer manually in application.rb:

module YourAppName
  class Application < Rails::Application
    require "#{Rails.root}/config/initializers/bower_rails.rb"

By default this line is added while running the generator.

Rake tasks

Once you are done with bower.json or Bowerfile you can run

  • rake bower:install to install packages
  • rake bower:install:deployment to install packages from bower.json
  • rake bower:update to update packages
  • rake bower:update:prune to update components and uninstall extraneous packages
  • rake bower:list to list all packages
  • rake bower:clean to remove all files not listed as main files (if specified)
  • rake bower:resolve to resolve relative asset paths in components
  • rake bower:cache:clean to clear the bower cache. This is useful when you know a component has been updated.

If you'd like to pass any bower CLI options to a rake task, like -f, -j, you can simply do:

rake bower:install['-f']

Capistrano 3 Configuration

While using Capistrano 3 and Capistrano Rails gem, it's needed to run bower install before assets compile. Add the following code to your deploy.rb, it will run rake bower:install before compiling the assets. CI=true flag is used not to ask for the analytics at the first bower install.

namespace :bower do
  desc 'Install bower'
  task :install do
    on roles(:web) do
      within release_path do
        with rails_env: fetch(:rails_env) do
          execute :rake, 'bower:install CI=true'
before 'deploy:compile_assets', 'bower:install'

Bower Configuration

If you provide a .bowerrc in the rails project root, bower-rails will use it for bower configuration. Some .bowerrc options are not supported: directory, cwd, and interactive. Bower-rails will ignore the directory property and instead will use the automatically generated asset path.

Bower Installation

Bower should be installed using npm. Bower can be installed globally (with $ npm install -g bower) or in node_modules in the root directory of your project.

Relative asset paths

Some bower components (eg. Bootstrap) have relative urls in the CSS files for imports, images, etc. Rails prefers using helper methods for linking to assets within CSS. Relative paths can cause issues when assets are precompiled for production.

Remember that you should have bower installed either locally in your project or on a remote server.

Bower Main Files

Each bower component should follow the bower.json spec which designates a recommended main directive that lists the primary files of that component. You may choose to reference these files if you are using the asset pipeline, in which case other extraneous includes of the bower component are not needed. The rake bower:clean task removes every file that isn't listed in the main directive, if the component specifies a main directive. Remember that you can extend the main directive in ruby DSL configuration. Otherwise, the library will remain as bower installed it. It supports wildcards in files listed in main directive.