Dockerized Firefox (shared X-Server)

conf.env

X_TOKEN="hostname/unix:0  MIT-MAGIC-COOKIE-1  md5orsomething"

docker-compose.yml

version: "3.9"

services:
  firefox:
    build: .
    env_file: conf.env
    environment:
      - DISPLAY=${DISPLAY}
    volumes:
      - /tmp/.X11-unix:/tmp/.X11-unix
    # DANGER: if you want isolation, change this!
    network_mode: host

docker-entrypoint.sh

touch /root/.Xauthority
xauth add $X_TOKEN
firefox-esr

Dockerfile

FROM debian:bullseye-slim

COPY docker-entrypoint.sh .

RUN apt-get update && apt-get install -y firefox-esr xauth

ENTRYPOINT /docker-entrypoint.sh