Rails API authentication goodies

application_controller.rb

class Api::HelloController < Api::ApplicationController
  include ActionController::HttpAuthentication::Token::ControllerMethods

  def authenticate_user!
    authenticate_or_request_with_http_token do |token|
      # decode and/or verify token (!)
    end
  end
end

posts_controller.rb

class PostsController < ApplicationController
  # All actions fail with 401 UNAUTHORIZED if no token is provided
  before_action :authenticate_user!
end