Restrict access of drawio app outside nextcloud

I have installed nextcloud with docker.
I want to integrate drawio app. I use GitHub - jgraph/docker-drawio: Dockerized based on tomcat:9-jre11 & tomcat:9-jre8-alpine official image. project.
I declare an outside fqdn. The app integration works successfully.
I would want to not access to the drawio app outside of nextcloud integration. At the moment, I can access to the external fqdn that I declare.
Do you have a solution to restrict the access of drawio app to my nextcloud users.