Try at a repro for selenium-docker + novnc hanging

Dockerfile

FROM ubuntu:jammy-20231128

# No interactive frontend during docker build
ENV DEBIAN_FRONTEND=noninteractive \
    DEBCONF_NONINTERACTIVE_SEEN=true

RUN apt-get update -qqy \
  && apt-get -qqy install \
  x11vnc xvfb \
  && rm -rf /var/lib/apt/lists/* /var/cache/apt/*

RUN <<EOF cat >> /opt/entrypoint.sh
#!/bin/bash
/usr/bin/Xvfb :99 -listen tcp -screen 0 1360x1020x24 & \
  sleep 1 && x11vnc -forever -rfbport 5900 -display :99.0 &
wait -n
exit $?
EOF

RUN chmod +x /opt/entrypoint.sh

CMD ["/opt/entrypoint.sh"]

EXPOSE 5900