How should I enable letsencrypt while discourse is beside other websites

Installation
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Here’s a slightly more detailed battle plan:

  • Backup /etc/nginx!
  • Update your existing configurations to listen on port 443. That’s invalid (nginx will speak HTTP on port 443), but we’ll fix that once we have the certificate. Doing so will free up port 80, so your existing configs cannot conflict with getting your first cert.
  • Add the first configuration snippet after the Add HTTPS section header in my offline guide to either one of your config files, or an additional one in sites-available that you link to in sites-enabled.
  • service nginx reload
  • Install Certbot and get a certificate. Follow the instructions in my guide to do so. Supply multiple domains (with multiple -d arguments) to Certbot so you get one cert that covers all relevant domains (talk.zabanshenas.com and www.talk.zabanshenas.com).
  • When you got the cert, adapt your existing configs (that you already changed to port 443) to match the last configuration snippet in the Add HTTPS section header in my guide: Update the listen line and add the lines that configure SSL. Leave the rest as is.
  • service nginx reload

If all went well, your sites should be served via HTTPS, and there should be an automatic redirect to HTTPS.