使用 NGINX 和負載平衡擴展 Node.js 應用程式

隨著 Node.js 應用程式的成長並接收更多流量，擴展對於保持效能和穩定性變得至關重要。在本文中，我們將深入探討有助於擴展 Node.js 應用程式的關鍵技術和工具，重點關注作為反向代理和負載平衡器的 NGINX，以及其他處理高流量和需求的方法。

在本文中，我們將介紹：

1. 什麼是 NGINX，為什麼它很重要？
2. 將 NGINX 設定為 Node.js 的反向代理。
3. 使用 NGINX 進行負載平衡。
4. 使用 NGINX 快取靜態內容。
5. Node.js 應用程式的擴充策略。
6. 縮放的真實用例。

什麼是 NGINX 以及為什麼它很重要？

NGINX 是一款高效能 Web 伺服器，以其作為反向代理、負載平衡器和HTTP 快取的功能而聞名。它可以有效地處理大量並發連接，使其成為擴展 Node.js 應用程式的優秀工具。

NGINX 的主要特點：

• 反向代理：它將傳入的客戶端請求路由到後端伺服器，幫助在多個伺服器之間分配負載。
• 負載平衡：NGINX 平衡多個伺服器執行個體之間的傳入流量，確保沒有單一伺服器被淹沒。
• 快取：它快取圖像、樣式表和腳本等靜態內容，減少重複產生相同回應的需要。

將 NGINX 設定為 Node.js 的反向代理

反向代理將客戶端請求路由到一個或多個後端伺服器。使用 NGINX 作為 Node.js 應用程式的反向代理可以從應用程式中卸載 SSL 終止、快取和負載平衡等任務。

分步設定：

1. 安裝 NGINX:
   首先，在您的伺服器上安裝 NGINX。在 Ubuntu 上，可以使用以下命令來完成：

   sudo apt update
   sudo apt install nginx
   

2. 設定 NGINX:
   在 /etc/nginx/sites-available/ 目錄中為 Node.js 應用程式建立一個新的設定檔。

這是一個範例設定檔：

   server {
       listen 80;
       server_name yourdomain.com;

       location / {
           proxy_pass http://localhost:3000; # Your Node.js app
           proxy_http_version 1.1;
           proxy_set_header Upgrade $http_upgrade;
           proxy_set_header Connection 'upgrade';
           proxy_set_header Host $host;
           proxy_cache_bypass $http_upgrade;
       }
   }

1. 啟用設定:
   建立從sites-available到sites-enabled的符號連結以啟用配置：

   sudo ln -s /etc/nginx/sites-available/yourdomain.com /etc/nginx/sites-enabled/
   

2. 重新啟動 NGINX:
   重新啟動 NGINX 以套用變更：

   sudo systemctl restart nginx
   

現在，NGINX 會將任何傳入請求轉送到在連接埠 3000 上執行的 Node.js 應用程式。反向代理設定可確保您的 Node.js 應用程式與直接客戶端存取隔離，從而增加一層安全性。

使用 NGINX 進行負載平衡

當流量增加時，單一 Node.js 實例可能難以處理所有傳入請求。負載平衡允許流量在應用程式的多個執行個體之間均勻分佈，從而提高可靠性和效能。

NGINX 負載平衡器設定：

1. 修改 NGINX 設定： 在 NGINX 設定檔中，定義 NGINX 將平衡請求的後端伺服器： ````nginx 上游節點應用程式{ 伺服器本地主機：3000； 伺服器本地主機：3001； 伺服器本地主機：3002； }

伺服器{
聽80；
server_name yourdomain.com;

   location / {
       proxy_pass http://node_app;
       proxy_http_version 1.1;
       proxy_set_header Upgrade $http_upgrade;
       proxy_set_header Connection 'upgrade';
       proxy_set_header Host $host;
       proxy_cache_bypass $http_upgrade;
   }

}

2. **Explanation**:
   - The `upstream` block defines a pool of Node.js servers running on different ports.
   - NGINX will distribute incoming requests evenly among these servers.

3. **Load Balancing Algorithms**:
   By default, NGINX uses a round-robin algorithm to balance traffic. You can specify other load balancing methods such as:
   - **Least Connections**: Sends requests to the server with the fewest active connections.
     ```nginx
     upstream node_app {
         least_conn;
         server localhost:3000;
         server localhost:3001;
     }
     ```

4. **Test and Scale**:
   You can now test the setup by running multiple instances of your Node.js app on different ports (3000, 3001, 3002, etc.) and monitor how NGINX balances the traffic.

## Caching Static Content with NGINX
Caching static content such as images, CSS, and JavaScript files can significantly reduce the load on your Node.js application by serving cached versions of these assets directly from NGINX.

### Caching Setup in NGINX:
1. **Modify Configuration for Caching**:
   Add caching rules to your server block:
   ```nginx
   server {
       listen 80;
       server_name yourdomain.com;

       location / {
           proxy_pass http://localhost:3000;
           proxy_set_header Host $host;
           proxy_cache_bypass $http_upgrade;
       }

       # Caching static content
       location ~* \.(jpg|jpeg|png|gif|ico|css|js)$ {
           expires 30d;
           add_header Cache-Control "public, no-transform";
       }
   }

1. 說明：
   • 有效期限30天；指令告訴 NGINX 將靜態檔案快取 30 天。
   • 這顯著提高了這些資產的回應時間，因為它們直接從 NGINX 提供，而無需接觸 Node.js 應用程式。

Node.js 應用程式的擴充策略

擴充 Node.js 應用程式不僅僅是使用 NGINX。以下是一些確保您的應用程式有效擴展的技術：

垂直縮放

垂直擴充是指升級伺服器的硬體資源，例如增加CPU數量或增加更多記憶體。雖然這可以在短期內提高性能，但它受到機器物理能力的限制。

水平縮放

水平擴展涉及在不同伺服器上運行應用程式的多個實例，並使用 NGINX 或雲端負載平衡器等工具平衡它們之間的流量。此方法允許透過添加更多實例來實現幾乎無限的擴展。

Clustering in Node.js

Node.js can run on multiple cores by using the built-in cluster module. This allows you to utilize all the available CPU cores on a server, increasing throughput.

Example:

const cluster = require('cluster');
const http = require('http');
const os = require('os');

if (cluster.isMaster) {
    const numCPUs = os.cpus().length;

    // Fork workers.
    for (let i = 0; i  {
        console.log(`Worker ${worker.process.pid} died`);
    });
} else {
    // Workers can share any TCP connection
    http.createServer((req, res) => {
        res.writeHead(200);
        res.end('Hello, world!\n');
    }).listen(8000);
}

This example shows how to use all CPU cores available on a machine by forking worker processes.

Real-World Use Case: Scaling an E-commerce Website

Problem: An e-commerce website is experiencing high traffic during sales events, leading to slow response times and occasional server crashes.

Solution:

• Use NGINX to distribute traffic across multiple Node.js servers running different instances of the application.
• Cache static assets like product images and JavaScript files with NGINX to reduce load on the server.
• Implement Node.js Clustering to fully utilize the server’s CPU resources.

Outcome: The e-commerce website can now handle thousands of concurrent users without slowdowns, ensuring a smooth user experience during peak traffic times.

Why SSL, Encryption, and Security Matter?

When scaling applications, security should not be overlooked. Implementing SSL (Secure Sockets Layer) ensures that data transmitted between the client and server is encrypted and protected from attacks.

Steps to Enable SSL:

1. Obtain an SSL Certificate from a trusted Certificate Authority (CA) like Let's Encrypt.

2. Configure NGINX to use SSL:

   server {
      listen 443 ssl;
      server_name yourdomain.com;
   
      ssl_certificate /etc/ssl/certs/yourdomain.crt;
      ssl_certificate_key /etc/ssl/private/yourdomain.key;
   
      location / {
          proxy_pass http://localhost:3000;
      }
   }
   

3. Redirect HTTP to HTTPS to ensure all traffic is secure:

   server {
      listen 80;
      server_name yourdomain.com;
      return 301 https://$host$request_uri;
   }
   

Conclusion

Scaling a Node.js application is essential as traffic and demand grow. By utilizing NGINX as a reverse proxy and load balancer, you can distribute traffic effectively, cache static assets, and ensure high availability. Combining these techniques with horizontal scaling and Node.js clustering enables your applications to handle massive traffic loads while maintaining performance and stability.

Implement these strategies in your projects to achieve better scalability, improved user experience, and increased uptime.

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