codeigniter

Configure Nginx to serve a CodeIgniter application installed in a subdirectory (e.g. /site) under the web root, with HTTPS and proper PHP routing.

Prerequisites

• Nginx installed with PHP-FPM
• SSL certificate in place
• CodeIgniter installed under /home/user/public_html/site/

Nginx Server Block

Edit your Nginx virtual host configuration:

server {
    listen 443 ssl;
    server_name example.com www.example.com;
    root /home/user/public_html/;
    index index.php index.html index.htm;

    ssl_certificate     /etc/pki/tls/certs/example.com.bundle;
    ssl_certificate_key /etc/pki/tls/private/example.com.key;
    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers on;

    # Subdirectory routing for CodeIgniter
    location /site/ {
        try_files $uri $uri/ /site/index.php?$args;
        add_header Strict-Transport-Security "max-age=31536000";
        add_header X-Content-Type-Options nosniff;
    }

    # Cache static assets
    location ~* \.(jpeg|jpg|png|gif|bmp|ico|svg|css|js)$ {
        expires max;
    }

    # PHP-FPM handler
    location ~ [^/]\.php(/|$) {
        fastcgi_pass   unix:/run/php/php8.1-fpm.sock;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }
}

Key Points

• The try_files directive routes all non-file requests to CodeIgniter's front controller.
• Set $config['base_url'] to https://example.com/site/ in application/config/config.php.
• Set $config['index_page'] = ''; to remove index.php from URLs.

Verify

nginx -t && systemctl reload nginx