In a Rack-based application, including frameworks built on top of Rack like Ruby on Rails and Sinatra, middleware plays a crucial role in processing HTTP requests and responses. When you're working within a Rack middleware, accessing request headers is straightforward because the request is represented as an environment hash (env) passed to the call method of your middleware.
Here's how to access request headers in different ways within a Rack middleware:
app/middleware/user_token_authenticator_middleware.rb
class UserTokenAuthenticatorMiddleware
def initialize(app)