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Nginx: A Brief Overview for Cloud Software Engineers

Nginx is a high-performance web server that also functions as a reverse proxy, load balancer, and HTTP cache. It is widely used due to its efficiency, scalability, and ability to handle a large number of simultaneous connections.

Key Components and Concepts

Web Server

  • Static Content: Nginx can serve static pages (HTML, CSS, JS, images) directly from the filesystem.
  • Resource Efficiency: It is highly resource-efficient, making it a popular choice for high-performance web servers.

Reverse Proxy

  • Intermediary: Nginx can act as an intermediary between clients (web browsers) and backend servers.
  • Request Forwarding: It receives client requests, forwards them to backend servers (e.g., Node.js, Python, PHP applications), and returns the responses to the client.
  • Benefits: Helps protect the backend server, hides internal infrastructure details, and distributes the workload.

Load Balancer

  • Request Distribution: Nginx can distribute requests among multiple backend servers to improve scalability and redundancy.
  • Algorithms: Supports various load-balancing algorithms, such as round-robin, least connections, and IP hash.

Cache

  • Response Caching: Nginx can cache responses from backend servers to reduce load and improve response times.

Configuration Structure

Nginx configuration is based on configuration blocks written in text files (usually located in /etc/nginx/nginx.conf and /etc/nginx/sites-available/).

Configuration Contexts

  • Main: Global Nginx settings.
  • HTTP: HTTP protocol-related settings.
  • Server: Defines a virtual server with specific settings for a domain or set of domains.
  • Location: Defines rules for URI matching and associated settings.

Common Directives

  • listen: Defines the port the server will listen on.
  • server_name: Defines the server name (domain).
  • location: Defines URI matching rules and associated settings.
  • proxy_pass: Defines the backend to which the request will be forwarded.
  • root/alias: Defines the document root directory for serving static files.

Example Configurations

Web Server Example

server {
    listen 80;
    server_name your_domain.com www.your_domain.com;

    location / {
        root /var/www/your_domain.com/html;
        index index.html index.htm;
    }

    location /css/ {
        alias /var/www/your_domain.com/css/;
    }

    location /scripts/ {
        alias /var/www/your_domain.com/scripts/;
    }

    error_log /var/log/nginx/your_domain.com_error.log;
    access_log /var/log/nginx/your_domain.com_access.log;
}

Reverse Proxy Example

server {
    listen 80;
    server_name your_domain.com www.your_domain.com;

    location / {
        proxy_pass http://localhost:3000;
        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;
    }
}

Load Balancer Example

upstream backend_servers {
    server backend1.example.com;
    server backend2.example.com;
}

server {
    listen 80;
    server_name your_domain.com www.your_domain.com;

    location / {
        proxy_pass http://backend_servers;
        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;
    }
}

Cache Example

proxy_cache_path /data/nginx/cache levels=1:2 keys_zone=my_cache:10m max_size=10g inactive=60m use_temp_path=off;

server {
    listen 80;
    server_name your_domain.com www.your_domain.com;

    location / {
        proxy_cache my_cache;
        proxy_pass http://localhost:3000;
        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;
        add_header X-Proxy-Cache $upstream_cache_status;
    }
}

Key Commands

Start/Restart Nginx:

sudo systemctl start nginx
sudo systemctl restart nginx

Test Configuration:

sudo nginx -t

Check Nginx Status:

sudo systemctl status nginx

Comparison with Cloud Services

  • AWS Elastic Load Balancer (ELB) and GCP Cloud Load Balancing: Similar to using Nginx as a load balancer to distribute traffic among backend servers.
  • AWS API Gateway and GCP API Gateway: Comparable to using Nginx as a reverse proxy to route requests to different backend services.
  • AWS CloudFront and GCP Cloud CDN: While not a complete replacement, Nginx can be used as a caching layer to improve performance.

https://nginx.org/en/docs/