Dump SASS/SCSS variables from a Rails app

gistfile1.rb

class Sass::Tree::Visitors::Perform
  def visit_variable(node)
    env = @environment
    env = env.global_env if node.global
    if node.guarded
      var = env.var(node.name)
      return [] if var && !var.null?
    end

    val = node.expr.perform(@environment)
    puts "#{node.name}: #{val}"
    if node.expr.source_range
      val.source_range = node.expr.source_range
    else
      val.source_range = node.source_range
    end
    env.set_var(node.name, val)
    []
  end
end

def dump_variables
  text = File.read("app/assets/stylesheets/application.scss")
  view_context = ActionView::Base.new

  engine = Sass::Engine.new(text, {
    syntax: :scss, cache: false, read_cache: false,
    load_paths: Rails.application.config.assets.paths,
    sprockets:  {
      context:     view_context,
      environment: view_context.assets_environment
    }
  })

  env = Sass::Environment.new
  nodes = Sass::Tree::Visitors::Perform.visit(engine.to_tree, env)
end

gistfile1.txt

Loading development environment (Rails 5.1.6.1)
irb(main):001:0> dump_variables
fa-sass-asset-helper: true
fa-font-path: "font-awesome"
fa-font-size-base: 16px
fa-css-prefix: fa
fa-version: "5.5.0"
fa-border-color: #eee
fa-inverse: #fff
fa-li-width: 2em
fa-fw-width: 1.25em
fa-var-500px: 
fa-var-accessible-icon: 
fa-var-accusoft: 
fa-var-acquisitions-incorporated: 
fa-var-ad: 
fa-var-address-book: 
fa-var-address-card: 
fa-var-adjust: 
fa-var-adn: 
fa-var-adversal: 
fa-var-affiliatetheme: 
fa-var-air-freshener: 
fa-var-algolia: 
fa-var-align-center: 
fa-var-align-justify: 
fa-var-align-left: 
etc.