Firefox headless not working within Docker as non-root user

Question

As the title says, I'm having trouble running Firefox in headless mode inside a Docker container as a non-root user. Consider the following Dockerfile, built with docker build -t firefox .

FROM python:3.8-buster
RUN apt-get update -qq \
    && apt-get install -qy \
        libappindicator1 \
        libasound2 \
        libatk1.0-0 \
        libc6 \
        libcairo2 \
        libcups2 \
        libdbus-1-3 \
        libexpat1 \
        libfontconfig1 \
        libgbm-dev \
        libgcc1 \
        libgconf-2-4 \
        libgdk-pixbuf2.0-0 \
        libglib2.0-0 \
        libgtk-3-0 \
        libnspr4 \
        libnss3 \
        libpango-1.0-0 \
        libpangocairo-1.0-0 \
        libpci-dev \
        libstdc++6 \
        libx11-6 \
        libx11-xcb1 \
        libxcb1 \
        libxcomposite1 \
        libxcursor1 \
        libxdamage1 \
        libxext6 \
        libxfixes3 \
        libxi6 \
        libxrandr2 \
        libxrender1 \
        libxss1 \
        libxtst6 \
        xdg-utils \
        nano

RUN wget https://download-installer.cdn.mozilla.net/pub/firefox/releases/85.0.2/linux-x86_64/en-US/firefox-85.0.2.tar.bz2 -O /firefox.tar.bz2
RUN tar -xf /firefox.tar.bz2 --directory /
WORKDIR /firefox
RUN ./firefox -CreateProfile "headless /profile-headless" -headless
RUN chmod -Rf 777 /firefox && chmod -Rf 777 /profile-headless
cmd ["./firefox", "-profile", "/profile-headless", "-headless", "--screenshot", "https://example.org"]

If I run a container as root, all is good and the process finishes (a few warnings appear, but it works overall):

$ docker run --rm firefox
*** You are running in headless mode.
[GFX1-]: glxtest: Unable to open a connection to the X server
[GFX1-]: glxtest: libEGL missing
$

However, if I run it as a different user, the same output appears, but the process hangs.

$ docker run --rm --user=1001 firefox
*** You are running in headless mode.
[GFX1-]: glxtest: Unable to open a connection to the X server
[GFX1-]: glxtest: libEGL missing

I tried assigning 777 permissions to both the directory that holds the binaries (/firefox) and the profile one (profile-headless), that doesn't seem to work. Probably some dependencies are not necessary, I just didn't want to spend time on that while I have bigger issues.

As a note, I initially encountered this while trying to run playwright-python inside Docker as non-root. The Chromium browser works just fine, but Firefox fails to initialize and playwright ends up throwing a timeout error. I dug deeper and realized that standalone Firefox was failing for me as well.

I suppose I must be missing some configuration, env variables or such. Any help would be much appreciated, thanks in advance!

Inandin

Did you fix it? – Educative

Answer 1

Playwright does use its own version of Firefox and WebKit. For that a specific Playwright build is required so the normal Firefox or Safari can't be used there which you are trying to install via apt.

In your scenario, you are probably looking for the command to automatically install the dependencies, which can get done by executing npx playwright install-deps, see here for reference.

Besides that it's recommended to use official Docker image, which is tested for every release and ensured that it contains all the necessary dependencies to run Playwright with all its features.

Pyromagnetic

The Playwright part is pure anecdote, it's not even present in the Dockerfile. The question is about running Firefox within docker as a non-root user. – Inandin

You can leverage the official Docker image which has already a non-root user available "pwuser". See here: playwright.dev/docs/docker#crawling-and-scraping. Are you using Playwright? If not, I would recommend to remove the tag since my comment is also then irrelevant. The error Unable to open a connection to the X server comes from that you launch firefox in normal headed mode. Use either xvfb-run or the headless mode to fix this. – Pyromagnetic