Caddy

Introduction

Caddy is a modern web server with automatic HTTPS, HTTP/2, and HTTP/3 support. It is known for its simplicity, ease of use, and flexible configuration, making it particularly suitable for static website hosting, reverse proxy, and API gateway scenarios.

Features

• Automatic HTTPS: Caddy can automatically obtain and renew SSL/TLS certificates without manual configuration. It supports certificate authorities like Let's Encrypt and ZeroSSL, providing secure HTTPS connections for your websites.
• HTTP/2 and HTTP/3 Support: Native support for HTTP/2 and HTTP/3 protocols, providing faster web page loading speeds and better user experience. HTTP/3 is based on the QUIC protocol and can provide better performance in unstable network environments.
• Flexible Configuration Options: Supports multiple configuration methods, including Caddyfile (simplified configuration syntax) and JSON configuration. Caddyfile syntax is concise and intuitive, easy to understand and maintain.
• Reverse Proxy and Load Balancing: reverse proxy functionality with support for various load balancing algorithms, including round-robin, least connections, IP hash, etc. Easy implementation of traffic distribution for microservice architectures.
• Static File Serving: Efficient static file server with support for file compression, cache control, directory browsing, and other features. Built-in file server with excellent performance, suitable for hosting static websites.
• Plugin System: Rich plugin ecosystem supporting authentication, logging, monitoring, caching, and various other functional extensions. You can select and configure appropriate plugins as needed.

Setup and Usage

Important Notes

Before using Caddy, please note the following important points:

1. Firewall Settings: Please ensure that the firewall allows access to the corresponding ports.
2. Domain Resolution: If using automatic HTTPS functionality, ensure that the domain correctly resolves to the server IP.
3. Permission Requirements: Caddy requires NET_ADMIN privileges to support certain network functions.

Configuration Steps

Basic Configuration

1. Create Caddyfile: Create a Caddyfile configuration file in the data/conf directory:

# Simple static website configuration
example.com {
    root * /srv
    file_server
}

2. Upload Website Files: Place your website files in the data/site directory.

Reverse Proxy Configuration

Configure reverse proxy to backend services:

api.example.com {
    reverse_proxy localhost:8080
}

Load Balancing Configuration

Configure load balancing for multiple backend services:

app.example.com {
    reverse_proxy {
        to localhost:8080
        to localhost:8081
        to localhost:8082
        lb_policy round_robin
    }
}

HTTPS Configuration

Caddy will automatically apply for SSL certificates for configured domains:

secure.example.com {
    root * /srv
    file_server
    tls your-email@example.com
}

Advanced Configuration

Custom Error Pages

example.com {
    root * /srv
    file_server
    handle_errors {
        @404 {
            expression {http.error.status_code} == 404
        }
        rewrite @404 /404.html
        file_server
    }
}

Access Log Configuration

example.com {
    root * /srv
    file_server
    log {
        output file /var/log/caddy/access.log
        format json
    }
}

Compression Configuration

example.com {
    root * /srv
    file_server
    encode gzip zstd
}

Troubleshooting

1. Configuration Syntax Errors: Check if the Caddyfile syntax is correct, you can use the caddy validate command to verify.
2. Certificate Application Failure: Ensure domain resolution is correct, port 80 is accessible, and firewall configuration is correct.
3. Port Conflicts: Check if other services are occupying the same ports.
4. Permission Issues: Ensure Caddy has sufficient permissions to access configuration files and website directories.

Through the above configuration and instructions, you can fully utilize Caddy's powerful features to build high-performance, secure web services.