How a Large Scale NestJS App Should ACTUALLY Look

Summary

This video explains how to scale an application using NestJS by applying clean architecture and domain-driven design principles. It demonstrates the process of growing a simple blog app from a small, personal project to a massive platform by adding new features and modules, such as user authentication, payments, and admin panels. It covers how to organize code, maintain modularity, and manage large teams. The video also explores advanced topics like multi-app workspaces, shared libraries, and transitioning to microservices for even greater scalability and performance.

Takeaways

• 😀 NestJS allows teams of any size to scale applications while keeping the code organized by following strict rules and software architecture.
• 😀 Clean Architecture and Domain-Driven Design (DDD) principles are essential for organizing and scaling applications.
• 😀 A simple app can start with basic features, such as post creation and storage, and then grow to include additional modules like users, comments, and authentication.
• 😀 Two types of modules exist in NestJS apps: domain-related modules (business logic) and technical modules (dev concerns).
• 😀 The key to success is ensuring modules have a single responsibility, focusing either on business features or technical capabilities.
• 😀 As your app grows, ensure code reuse by organizing shared functionalities like decorators, guards, filters, and providers into a common folder.
• 😀 Group related modules together (e.g., authentication and users) and assign dedicated development teams to each area.
• 😀 Identifying module groups based on shared business logic helps maintain organization as the app scales (e.g., role-based authentication in the core module).
• 😀 As the app becomes more popular, adding features like payments, reactions, and media requires expanding the codebase while keeping it maintainable.
• 😀 NestJS supports the use of multiple applications within a single project, enabling you to scale by creating separate apps (e.g., a blog app and admin panel) that share components through libraries.
• 😀 As the app grows further, transitioning to a microservices architecture can provide better scalability, with independent services (e.g., blog, user, admin) using shared libraries for common functionality.

Q & A

How do large engineering teams manage a shared codebase effectively?

Large engineering teams manage a shared codebase by following strict rules, agreeing on software architecture, and ensuring code remains organized. They use principles like clean architecture and domain-driven design to scale applications while keeping the code maintainable.

Can the same principles applied to large engineering teams be used with NestJS?

Yes, the same principles can be applied to NestJS, regardless of the team or application's size. With NestJS, you can start small and scale your application effortlessly while maintaining an organized codebase.

What is the key to keeping a codebase organized as an application grows?

The key is organizing modules based on business logic and concerns. Modules should have a single responsibility, focusing either on business domains or technical capabilities. This ensures scalability and maintainability.

How do you differentiate between different types of modules in an application?

Modules can be divided into two types: those related to business domains, which provide end-user features, and those related to technical concerns, which focus on development-specific functionality. This distinction helps keep the app organized as it grows.

How can a small application grow into a medium-sized application?

A small application can grow by adding new features and modules, such as user authentication, payment systems, and comments. As new developers are added to the team, the application evolves into a medium-sized system, requiring better code management and more structured modules.

What is the importance of reusing code when scaling an application?

Reusing code when scaling ensures that new modules don’t duplicate efforts. Common elements like decorators, guards, middleware, and providers can be shared across the application, reducing redundancy and making it easier to maintain.

How can you organize shared code across modules in a NestJS application?

You can create a 'common' folder to store shared code or organize the application in a modular hierarchy, grouping related modules together. For example, authentication and user modules might be placed under a core module.

What is the advantage of grouping related modules together in NestJS?

Grouping related modules together helps in organizing the application based on business logic. It allows teams to focus on specific areas of the application, improving clarity, maintainability, and scalability.

How can you scale a NestJS application to include an admin panel?

Instead of creating a separate NestJS project, you can convert your application into a workspace containing multiple applications. This way, you can have both a blog app and an admin app within the same project, sharing components through libraries.

How does modularization in NestJS help with product evolution?

Modularization in NestJS allows applications to grow in a manageable way. By separating concerns into distinct modules, teams can innovate on new features while maintaining a well-organized and scalable architecture.

What is the next step when a NestJS application becomes too complex for a single monolithic system?

When the application grows too complex, you can adopt a microservices architecture. This involves splitting the monolithic system into smaller, independently deployable NestJS applications that communicate through shared services, while still reusing common libraries.