Load external gem (out of Gemfile) into Rails console

require_external.rb

def require_external(gem_name=nil, gem_version="*", gem_libdir="lib")
  gem_dir = Dir["#{`gem env gemdir`.strip}/gems/#{gem_name}-#{gem_version}"].first

  raise "Gem '#{gem_name}' version '#{gem_version}' not found" if gem_dir.nil?

  gemlib = Dir["#{gem_dir}/#{gem_libdir}/#{gem_name}.rb"].first

  raise "Gem lib file '#{gemlib}' not found" if gemlib.nil?

  puts "Loading gem '#{gem_name}' version '#{gem_version}' from #{gemlib}"

  $LOAD_PATH << Dir["#{gem_dir}/#{gem_libdir}"].first
  
  require gemlib
end

Usage

# In Rails console
require_external 'seed_dump'
require_external 'seed_dump', '3.3.1' # Specify version