负载均衡与代理
理解负载均衡器和反向代理如何分配流量，以及如何提升 NestJS 服务的可用性。
负载均衡与代理 是 CoddyKit 上的免费 NestJS Enterprise Backend APIs 课时。 这是第 3 节课，共 6 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 NestJS Enterprise Backend APIs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 NestJS Enterprise Backend APIs 课程共包含 6 节课。
本课时的部分内容尚未翻译，以英文显示。
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.
常见问题解答
「负载均衡与代理」课时是免费的吗？
是的 — 「负载均衡与代理」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 NestJS Enterprise Backend APIs 课程的其余内容，请升级到 CoddyKit PRO。 NestJS Enterprise Backend APIs 课程共包含 6 节课。
「负载均衡与代理」这节课中我会学到什么？
理解负载均衡器和反向代理如何分配流量，以及如何提升 NestJS 服务的可用性。 你通过在浏览器中直接运行的动手代码来练习 NestJS Enterprise Backend APIs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 NestJS Enterprise Backend APIs 需要有经验吗？
无需任何先前经验。CoddyKit 上的 NestJS Enterprise Backend APIs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 3 节课，共 6 节。
「负载均衡与代理」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 NestJS Enterprise Backend APIs 课中编写并运行代码吗？
能。每节 NestJS Enterprise Backend APIs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。