Firebase is a great platform that offers a wide range of services to developers, making it easy to build, improve, and grow their apps. One of these services is Firebase Auth, which allows for easy user authentication using its JavaScript SDK. Despite Firebase Auth being an awesome service and abstracting a lot of the complex code needed to build user authentication, I recently found one limitation. Firebase Auth doesn't persist the session across multiple domains. This means that if we use the same Firebase Auth for two different domains, such as https://example1.com and https://example2.com, we have to sign in to both applications on both domains independently. Currently, Firebase doesn't have a built-in feature to handle this situation out of the box.

This blog article is a continuation from the previous blog article about Nest.js Authorisation with Firebase Auth. If you have’t read that article you will not be able to follow along. The previous article can be found below. In this article we will be using custom route decorators in Nest. We will be creating our own @CurrentUser decorator and use it in the module controllers anytime we want to get the current logged user. Let’s have a look at how we can achieve this.

In this blog article we will be creating a Nest application where users (with different roles) can sign-up and sign-in to the application. Specific permissions can be configured for each user access to specific endpoints, based on the user role. We are going to use Firebase Auth to help us with user Authentication and Authorisation. Before we continue let’s first install the Nest CLI. That will help us create our project much quicker. To install Nest CLI globally use the following command in your terminal

Modules have become a major part of the JavaScript ecosystem. They allow us to split our JavaScript programs up into separate smaller parts, called modules, that can be imported when needed. In this article, we will have a look at how we can include local modules in our Node.js app, and then see how that differentiates from including them in Firebase Cloud Functions. Before we continue, do note that this is not an introduction to Firebase. A basic understanding of Firebase and JavaScript is required before reading on about the examples that I'm about to explain.

Firebase as a platform that offers a wide range of services to developers to build, improve, and grow their apps with little or almost no effort. This includes services like authentication, databases, analytics, file storage, push messaging and more. When it comes to user authentication, Firebase provides an Authentication service that allows for codes to be written in order for users to be logged into an app right from the client side, and limit user access to resources in other Firebase products. This is fairly simple to use without the need to implement any backend solution. Firebase also provides an Admin SDK that allows developers to build a custom backend if required.