Thin with SSL as default server for use with rails server. Works with Rubymine.

rails

#!/usr/bin/env ruby
require 'rack'

# Thin SSL workaround
module Rack
  module Handler
    class Thin
      def self.run(app, options={})
        app = Rack::Chunked.new(Rack::ContentLength.new(app))
        server = ::Thin::Server.new(options[:Host] || '0.0.0.0',
                                    options[:Port] || 3000,
                                    app)
        server.ssl = true
        server.ssl_options = {
            :private_key_file => SERVER_KEY,
            :cert_chain_file => SERVER_PEM
        }
        yield server if block_given?
        server.start
      end
    end
  end
end
# Workaround end

APP_PATH = File.expand_path('../../config/application', __FILE__)
require_relative '../config/boot'
require 'rails/commands'

Its working with RubyMine 6.3.3. Thank you.

Also you can pass private_key_file and cert_chain_file as nil

  server.ssl_options = {
            :private_key_file => nil,
            :cert_chain_file => nil
        }