AppArmor in Docker: Warning: unable to find a suitable fs in /proc/mounts, is it mounted? Use --subdomainfs to override

Question

I am trying to containerize my application that uses AppArmor to execute programs in a sandboxed environment (online code judge). The application works perfectly fine on my machine, but I am having trouble getting my policies inside the dockerized version of it to work.

Here is my Dockerfile:

FROM node:18-buster

RUN apt-get update && \
    apt-get install -y apparmor apparmor-utils && \
    mkdir /etc/apparmor.d/coderatic && \
    chmod 700 /etc/apparmor.d/coderatic

# Two policies I want apparmor inside my container to use
COPY coderatic-bin-policy /etc/apparmor.d/coderatic/
COPY coderatic-py3-policy /etc/apparmor.d/coderatic/

WORKDIR /server

COPY ./package*.json ./
RUN npm install

COPY . .


ENV PORT=3000

EXPOSE 3000

CMD sh -c 'apparmor_parser -r -W /etc/apparmor.d/coderatic/coderatic-bin-policy && \
    apparmor_parser -r -W /etc/apparmor.d/coderatic/coderatic-py3-policy && \
    npm run dev'

But I am getting the following error when running the container:

Warning: unable to find a suitable fs in /proc/mounts, is it mounted?
Use --subdomainfs to override.

I have tried using the --subdomainfs option, but I am unsure what argument to pass to it. I tried using /etc/apparmor.d, but this resulted in a different error that persisted regardless of the path I used.