Jekyll Nginx config, assumes you're using a versioned deployment dir that matches the domain name and uses Let's Encrypt SSL cert.

jekyll.nginx.conf

server {
  listen       80;
  server_name  yourdomain.com;
  return       301 https://yourdomain.com$request_uri;
}

server {
  listen       443 ssl http2;
  listen       [::]:443 ssl http2;
  server_name  yourdomain.com;

  ssl_certificate      /etc/letsencrypt/live/yourdomain.com/fullchain.pem;
  ssl_certificate_key  /etc/letsencrypt/live/yourdomain.com/privkey.pem;
  ssl_protocols        TLSv1 TLSv1.1 TLSv1.2;
  ssl_ciphers          HIGH:!aNULL:!MD5;

  access_log  /var/www/yourdomain.com/logs/access.log;
  error_log   /var/www/yourdomain.com/logs/error.log;

  error_page 404 /404.html;

  ## Root and index files.
  root /var/www/yourdomain.com/current/;
  index index.html;
  default_type "text/html";
  autoindex off;

  location  /404.html {
    internal;
  }

  ## If no favicon exists return a 204 (no content error).
  location = /favicon.ico {
    try_files $uri =204;
    log_not_found off;
    access_log off;
  }

  ## Don't log robots.txt requests.
  location = /robots.txt {
    allow all;
    log_not_found off;
    access_log off;
  }

  if (!-f "${request_filename}index.html") {
    rewrite ^/(.*)/$ /$1 permanent;
  }

  if ($request_uri ~* "/index.html") {
    rewrite (?i)^(.*)index\.html$ $1 permanent;
  }   

  if ($request_uri ~* ".html") {
    rewrite (?i)^(.*)/(.*)\.html $1/$2 permanent;
  }

  location / {
    try_files $uri.html $uri $uri/ =404;
  }
}