How to setup chrome sandbox on docker container?

Question

I am trying to run chrome on a docker container, but I can't properly set up chrome-sandbox and in every place I search people tell to just disable sandbox by passing --no-sandbox. I feel that's a workaround from same team of "run as root". This is my dockerfile:

FROM buster-slim

# install chrome
RUN adduser --system --group chrome
RUN apt-get update \
    && apt-get install -y --no-install-recommends wget \
    && wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb \
    && apt install -y --no-install-recommends ./google-chrome-stable_current_amd64.deb \
    && rm google-chrome-stable_current_amd64.deb \
    && chown root:root -R /opt/google/chrome/ \
    && chmod 755 -R /opt/google/chrome/ \
    && chmod 4755 -R /opt/google/chrome/chrome-sandbox

USER chrome
ENTRYPOINT ["google-chrome", "--headless", "--disable-gpu"]

but it crashes with illegal instruction error:

Failed to move to new namespace: PID namespaces supported, Network namespace supported, but failed: errno = Operation not permitted
Failed to generate minidump.Illegal instruction (core dumped)

it does not crashes if I pass --no-sandbox.

Answer 1

It happens because docker's default seccomp policy denies access to syscalls required by chrome to properly setup sandboxing, thus causing "Operation not permitted" error, being them: clone, unshare, arch_prctl, chroot and ptrace.

Extend the default policy to add those syscalls to allowed list, here is a diff from the default:

{
    "syscalls": [
        {
            "names": [
                "clone",
                "unshare",
                "arch_prctl",
                "chroot",
                "ptrace"
            ]
        }
    ]
]

and pass the json file to --security-opt seccomp=file.json argument of docker run or corresponding argument in compose file:

version: "3.9"

services:
  chrome:
    security_opt:
      - seccomp=file.json