nginx-rewrite.conf

# SSL configuration
#
server {

  listen 8964 ssl;

# allowing only local networks and cloudflare CDN IPs for security
  allow  127.0.0.0/8;
  allow  192.168.2.0/24;
# cloudflare IPs. see https://www.cloudflare.com/ips/
  allow  173.245.48.0/20;
  allow  103.21.244.0/22;
  allow  103.22.200.0/22;
  allow  103.31.4.0/22;
  allow  141.101.64.0/18;
  allow  108.162.192.0/18;
  allow  190.93.240.0/20;
  allow  188.114.96.0/20;
  allow  197.234.240.0/22;
  allow  198.41.128.0/17;
  allow  162.158.0.0/15;
  allow  104.16.0.0/12;
  allow  172.64.0.0/13;
  allow  131.0.72.0/22;
  deny   all;

  server_name           api.davidxiao.me;
  ssl_certificate       /etc/mycert/cloudflare/origin-cert.pem;  # cloudflare self-signed cert only for CDN purposes
  ssl_certificate_key   /etc/mycert/cloudflare/priv.key;   # cloudflare self-signed cert only for CDN purposes

  root /var/www/html;

# Add index.php to the list if you are using PHP
  index index.html index.htm index.nginx-debian.html;

  location /remark42 {
    # rewrite so as to remove /remark42 from the request URL and pass the rest onto the docker
    rewrite ^/remark42(/.*)$ $1 break;
    proxy_pass http://localhost:8899;  #remark42 container mapped to the host poort 8899
  }

  location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
    try_files $uri $uri/ =404;
  }

}

Check out https://davidxiao.me/post/adding-your-own-commenting-system-to-a-static-site/ and https://davidxiao.me/post/hosting-multiple-containers-with-nginx-rewrite-rules/