Load Balancing and Proxies
Understand how load balancers and reverse proxies distribute traffic and enhance the availability of your NestJS services.
Load Balancing and Proxies is a free NestJS Enterprise Backend APIs lesson on CoddyKit — lesson 3 of 6. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the NestJS Enterprise Backend APIs learning path, one of 6 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Scaling Up Your NestJS App
Imagine your NestJS application becomes super popular! A single server might struggle to handle thousands of users all at once. This is where Load Balancing and Reverse Proxies come in.
They are essential tools for building scalable and highly available backend services, ensuring your application can grow with demand.
What is Load Balancing?
Load Balancing is the process of distributing incoming network traffic across multiple servers. Think of it as a traffic controller for your web requests.
- It prevents any single server from becoming a bottleneck.
- It improves application responsiveness by sharing the workload.
- It enhances reliability by directing traffic away from unhealthy servers.
How Load Balancers Work
When a client makes a request, it first hits the load balancer. The load balancer then decides which backend server (e.g., a NestJS instance) should handle that request.
It uses various algorithms and continuously monitors the health of each server to ensure requests are only sent to those that are up and running.
Common Load Balancing Algorithms
Load balancers use different strategies to distribute traffic:
- Round Robin: Distributes requests sequentially to each server in turn. Simple and effective for equally powerful servers.
- Least Connections: Sends new requests to the server with the fewest active connections. Good for servers handling varying workloads.
- IP Hash: Directs requests from the same client IP address to the same server. Useful for maintaining 'sticky sessions'.
Introducing the Reverse Proxy
A Reverse Proxy is a server that sits in front of web servers and forwards client requests to those web servers. It acts as an intermediary for requests from clients seeking resources from backend servers.
Unlike a forward proxy (which protects clients), a reverse proxy protects and abstracts backend servers.
Reverse Proxy Benefits for NestJS
Using a reverse proxy like Nginx in front of your NestJS application offers several advantages:
- Security: Hides the identity of backend servers and can filter malicious requests.
- SSL Termination: Handles HTTPS encryption/decryption, offloading this work from your NestJS app.
- Caching: Can cache static content, reducing the load on your application servers.
- Compression: Compresses responses to save bandwidth.
Load Balancer vs. Reverse Proxy
While both distribute traffic and sit in front of servers, their primary goals differ:
- A Load Balancer's main job is to evenly distribute load across multiple servers to improve performance and reliability.
- A Reverse Proxy's main job is to provide a single point of access, enhance security, and offer features like caching or SSL termination, potentially to a single backend server or a group.
Often, a reverse proxy can also perform load balancing functions, blurring the lines between them.
Nginx as a Reverse Proxy Example
Nginx is a popular choice for both reverse proxying and load balancing. Here's a simplified Nginx configuration snippet that proxies requests to a NestJS application running on port 3000:
This config listens on port 80 and forwards all requests to your NestJS server.
http {
upstream nestjs_app {
server 127.0.0.1:3000;
# server 127.0.0.1:3001; # Add more for load balancing
}
server {
listen 80;
server_name your_domain.com;
location / {
proxy_pass http://nestjs_app;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
}
}
}Scaling NestJS with Proxies & Balancers
By placing a load balancer or reverse proxy in front of multiple NestJS instances, you enable horizontal scaling. This means you can add more NestJS servers as your traffic grows, without changing your application code.
The proxy/balancer handles distributing requests, making your application more resilient and performant.
Check Your Understanding
Which of the following are primary benefits of using a Reverse Proxy with a NestJS application?
Recap: Distributing Your Load
In this lesson, we explored Load Balancing and Reverse Proxies. Load balancers distribute traffic to prevent bottlenecks and improve availability, while reverse proxies offer benefits like security, SSL termination, and caching.
Together, these tools are crucial for building robust, scalable, and high-performance NestJS applications capable of handling increasing user demand.
Frequently asked questions
Is the “Load Balancing and Proxies” lesson free?
Yes — the full text of “Load Balancing and Proxies” is free to read here on the web, and the NestJS Enterprise Backend APIs course includes 6 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the NestJS Enterprise Backend APIs course, upgrade to CoddyKit PRO.
What will I learn in “Load Balancing and Proxies”?
Understand how load balancers and reverse proxies distribute traffic and enhance the availability of your NestJS services. You practise NestJS Enterprise Backend APIs with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start NestJS Enterprise Backend APIs?
No prior experience is required. NestJS Enterprise Backend APIs on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 6, so you can start here or from the beginning and move at your own pace.
How long does the “Load Balancing and Proxies” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this NestJS Enterprise Backend APIs lesson?
Yes. Every NestJS Enterprise Backend APIs lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.