What is Monorepo? — An Example Using Nx (NestJS Microservices)

Introduction

A monorepo is a single repository containing multiple distinct projects, each with well-defined relationships, storing all your application and microservice code in a single source code repository like Git.

A monorepo with unified and automated build and deploy pipelines can mitigate many development issues. The best approach to fully utilize a monorepo architecture is to combine it with a microservices architecture.

Benefits of Monorepo

1. Code Utilization: Reuse of class functions and services leads to a reduction in coding lines, enhancing efficiency and maintainability.
2. Maintaining Documentation: Centralized documentation enhances development consistency and serves as a unified reference resource.
3. Simplified Refactoring: Refactoring is safer as changes across all projects can be made simultaneously, reducing the risk of breaking dependencies.
4. Code Reuse: Developers can easily share code for efficient collaboration and reuse across projects in the same repository.
5. Consistent Commits: Atomic commits sync changes across multiple projects in one go, ensuring synchronization.

Monorepo using Nx

Nx is an open-source build system that boosts developer productivity, optimizes CI performance, and ensures code quality.

Nx features a powerful CLI and VSCode extension, enhancing development with seamless build configuration, eslint, prettier, and test configurations such as Jest.

It facilitates the creation and configuration of these settings through easy-to-use CLI commands or the VSCode extension.

VSCode Extention — Nx Console

Example of a Monorepo using Nx

Certainly, let’s elaborate on building a basic monorepo architecture project using Nx with React and multiple NestJS projects, focusing on two microservices: ‘user-service’ and ‘auth-service.’

Overview of microservices

Microservices architecture is an approach to software development where a complex application is divided into small, independent services that communicate through APIs. Each microservice focuses on a specific business capability, enabling independent development, deployment, and scalability.

Let’s dive into the code. First, open up the terminal and navigate to the directory where you want to create the project. Run the following command:

“monorepo-demo” — Workspace Name

npx create-nx-workspace@latest monorepo-demo --preset=nest

After running this command in the terminal, it will prompt you with several options. Once you’ve completed the setup, you’ll have successfully created a monorepo workspace using Nx with a Nest application.

There are two possible ways to create applications or libraries: through the Nx console in the VS Code extension or via terminal commands. In this example, we’ll use terminal commands.

Step 1: Install the @nx/react package to create a React application.

npm i @nx/react --save

Step 2: Generate a React application.

nx generate @nx/react:application apps/admin-panel

Step 3: Create a directory for the library named ‘libs’ in the root path of the workspace.

mkdir libs

Step 4: Install the @nrwl/js package to enable Nx generation for JavaScript-related projects.

npm i @nx/js --save

Step 5: Create a common JavaScript library to be utilized in both the Nest application and the React application.

nx generate @nx/js:library libs/common

Utilize the common library to create an interface that can be accessed in both the Nest and React applications.

Following these steps, you will have the initial workspace set up for a large project using monorepo architecture.

Here is the link to my GitHub repository for the monorepo project with the initial setup of a React app and two Nest.js services, including a README and code in working condition.

Repo Link -> Monorepo Demo

Monorepo Tools

Nx

• Nx is an open-source build system that boosts developer productivity, optimizes CI performance, and ensures code quality.

Lerna

• Lerna is a fast-build system for managing and publishing multiple JavaScript/TypeScript packages from a single repository.

Bazel

• Bazel, by Google, is a build and test tool supporting incremental builds and a unified approach for diverse languages and platforms.

Rush

• Rush is a monorepo management tool for TypeScript and JavaScript projects, offering parallelized builds, incremental builds, and version management.

Concluding Thoughts:
I appreciate your understanding. Please don’t hesitate to share any feedback or suggestions regarding the code or content. I’m committed to promptly addressing any comments and ensuring a positive collaboration.

Cheers and happy coding!