Thanks for asking question! You may try using the EXPOSE instruction to open port 2222 in the container. Although the root password is known, port 2222 is inaccessible from the internet. It's accessible only by containers within the bridge network of a private virtual network.
EXPOSE 80 2222
Also refer to Open an SSH session to a Linux container in Azure App Service for more details on SSH connection
Let us know if you have further question on this.