How To Freeze Gems In Rails

Here’s how to freeze any gem into your Rails app. This is a simplified version of the larger discussion Vendor Everything at err.the_blog.

First, copy the gems you want into the directory vendor/gems.

mkdir vendor/gems
cd vendor/gems
gem unpack some_gem_name # repeat for each gem

Next, edit config/environment.rb and add the following inside the =Rails::Initializer.run= block:

Rails::Initializer.run do |config|
  # add the next three lines
  config.load_paths += Dir["#{RAILS_ROOT}/vendor/gems/**"].map do |dir|
    File.directory?(lib = "#{dir}/lib") ? lib : dir
 end
end

Now you can require those gems in your code, even if the system you are running on doesn’t have that gem installed.