To redirect your website from HTTP to HTTPS using Nginx, follow these steps:

1. Locate the Configuration File:

   • For RHEL-based systems: /etc/nginx/conf.d/default.conf
   • For Debian-based systems: /etc/nginx/sites-enabled/default

2. Identify the Server Block for Port 80:

   • Use commands like sudo nginx -T | grep -iw "configuration file" or look for include directives to find the relevant configuration file.

3. Add the Redirect Directive:

   • Open the identified server block in your preferred text editor.
   • Ensure it is within the server block listening on port 80.
   • Add the line return 301 https://$server_name$request_uri; as the last directive in the block.

4. Example Configuration:

   listen 80;
   server_name your_domain.com www.your_domain.com;
   return 301 https://$server_name$request_uri;
   

5. Restart Nginx:

   • After making changes, restart Nginx to apply the new configuration.

6. Test the Redirect:

   • Visit your site over HTTP to ensure it redirects correctly to HTTPS.