Rails Middleware: (Almost) Everything You Need to Know

Most web applications have some functionality that's common for many (or even all) HTTP requests. For example, an application will authenticate the user and log the incoming HTTP request, add new headers, or check if the request is for a static file and serve it from a CDN without hitting the app server.Middleware is an elegant way to organize this common functionality, instead of spreading it everywhere in your application code, which should focus on the logic of your application. In its essence, middleware is a self-contained application that operates on a request independently before or after your main application.