RailsAdmin is an awesome gem when you want to build a not-so-much custom admin panel. Unfortunately it’s not mentioned in documentation (or at least I couldn’t find it) how to use it with HTTP Basic authentication. Here is an example of how to do this (put this in your config/initializers/rails_admin.rb file):

RailsAdmin.config do |config|
  config.authenticate_with do
    authenticate_or_request_with_http_basic do |username, password|
      username == 'user' &&
      password == 'password'
    end
  end

  # Other config stuff should go here
end

You should also use gem like SettingsLogic for storing credentials like this:

RailsAdmin.config do |config|
  config.authenticate_with do
    authenticate_or_request_with_http_basic do |username, password|
      username == System::Settings.admin.username &&
      password == System::Settings.admin.password
    end
  end

  # Other config stuff should go here
end