Limit Ubuntu-SSH Image Container's Disk Size

How can I limit the storage use of a Ubuntu 20.04 Image Container with SSH Enabled in Docker?

I understand that one should not use Docker as a VM Technology but this is only for educational purposes

docker-compose.yml:

version: '3'
services:
  ubuntu-vm:
    build: .
    image: ubuntu-ssh
    ports:
      - "2222:22"
    environment:
      - ROOT_PASSWORD=password
    restart: always
    networks:
      mynetwork:
        ipv4_address: 172.24.0.2
networks:
  mynetwork:
    driver: bridge
    ipam:
      config:
        - subnet: 172.24.0.0/16

Dockerfile:

FROM ubuntu:latest
RUN apt-get update && \
    apt-get install -y openssh-server && \
    mkdir /var/run/sshd
RUN echo 'root:password' | chpasswd
RUN sed -i 's/#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config
EXPOSE 22
CMD [ "/usr/sbin/sshd", "-D", "-e" ]

I have tried adding storage_opt: size: 100G to the compose file, but upon doing df -H in the container, it returned the host disk available size and disk usage (in this example 400gb used, 1.9tb available)

Will I have to create a disk in my host and map it my container's /dev/sdx disk? Or is there a better way to do it where the container does have access to the host disk as full but a chunk of it.

> I have tried adding storage_opt: size: 100G to the compose file, but upon doing df -H in the container, it returned the host disk available size and disk usage (in this example 400gb used, 1.9tb available)

Sure, because df -h will show the size of the device, not available quota limits on specific filesystem. Create a file bigger than 100G to check.

$ docker run -ti --rm --storage-opt size=5G alpine
# dd if=/dev/random of=file bs=10M count=1023
dd: error writing 'file': Quota exceeded
512+0 records in
511+0 records out

This is most probably docker storage driver specific - I tested on btrfs.