How to put Strapi into a folder

System Information
  • Strapi Version: 3.6.8
  • Operating System: centos
  • Database: mysql
  • Node Version: 14.8.0
  • NPM Version: 6.14.8
  • Yarn Version: 1.21.1

I want to serve my strapi inside a folder, eg. https://my.site/folder/admin

I tried in NGINX to serve whole site under my.site/folder
but the internal api from strapi will still lead to my.site/api/anyapi, but not my.site/folder/api/anyapi
is there any plublic_url param I can set?

Thx very much