nano /etc/caddy/Caddyfile

domain2.com {
reverse_proxy 0.0.0.0:
}
yourdomain.com {
    @allowed_origins {
        origin_regexp ^(https?://(app\.example\.com|localhost:3000|dev\.site\.org))$
    }
    
    header @allowed_origins Access-Control-Allow-Origin "{http.request.header.origin}"
    header @allowed_origins Access-Control-Allow-Methods "GET, POST, OPTIONS"
    header @allowed_origins Access-Control-Allow-Credentials "true"
    
    reverse_proxy localhost:8055
}
yourdomain.com {
    # Handle OPTIONS preflight requests
    @preflight method OPTIONS
    
    # Workaround for older Caddy versions (no 'origin' matcher)
    @cors_origin {
        header Origin ^(http://localhost:3000|https://localhost:3000|https://.*\.example\.com|https://your-production-domain\.com)$
    }
    
    # CORS headers for actual requests
    header @cors_origin Access-Control-Allow-Origin "{http.request.header.origin}"
    header @cors_origin Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS"
    header @cors_origin Access-Control-Allow-Headers "*"
    header @cors_origin Access-Control-Allow-Credentials "true"
    header @cors_origin Vary Origin
    
    # Special handling for preflight requests
    header @preflight Access-Control-Allow-Origin "{http.request.header.origin}"
    header @preflight Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS"
    header @preflight Access-Control-Allow-Headers "*"
    header @preflight Access-Control-Max-Age "3600"
    
    # Proxy to your backend
    reverse_proxy localhost:8055
    
    # Respond to OPTIONS requests immediately
    respond @preflight 204
}

# The Caddyfile is an easy way to configure your Caddy web server.
#
# Unless the file starts with a global options block, the first
# uncommented line is always the address of your site.
#
# To use your own domain name (with automatic HTTPS), first make
# sure your domain's A/AAAA DNS records are properly pointed to
# this machine's public IP, then replace ":80" below with your
# domain name.

:80 {
        # Set this path to your site's directory.
        root * /usr/share/caddy

        # Enable the static file server.
        file_server

        # Another common task is to set up a reverse proxy:
        # reverse_proxy localhost:8080

        # Or serve a PHP site through php-fpm:
        # php_fastcgi localhost:9000
}

# Refer to the Caddy docs for more information:
# https://caddyserver.com/docs/caddyfile