How to forward Docker for Mac to X11?

Solution

After installing XQuartz you will need to restart your computer as horcle_buzz suggested; starting a new terminal session is not enough.

After a reboot you can grant access for whatever you need using the xhost command. Just be careful and understand the consequences of too permissive a rule. This other discussion has more info: Running Chromium inside Docker - Gtk: cannot open display: :0

Additional findings

Some extra things I discovered along the way:

• XQuartz must be running first:

  $ open -a XQuartz
  

• You can expose 127.0.0.1 instead of looking up your local IP (caveat emptor: I'm not an expert on the implications of this setting):

  $ xhost + 127.0.0.1
  127.0.0.1 being added to access control list
  

• You can use the special host.docker.internal identifier with docker run:

  $ docker run -e DISPLAY=host.docker.internal:0 jess/firefox
  # 🧙‍♀️ magic 🧙‍♂️
  

• At least for me, ctrl + c does not shutdown the container; I need to close the X11 window manually.
• If you quit XQuartz, you must re-auth with xhost after starting it again (the permission doesn't "stick").
• Doing it this way I didn't need to mount /tmp/.X11-unix when calling docker run.

I tested this with XQuartz 2.7.11 and Docker Desktop 2.1.0.2 on macOS Mojave (10.14.6).

I have xQuartz 2.7.11 installed on Mac OS.

I was getting the following error <program>: cannot connect to X server <ip>:0 when trying to run docker container. I tried downgrading XQuartz but it still didn't fix my issue.

A crucial piece to to the setup is to add your ip access control list for xhost.

xhost + $(ipconfig getifaddr en0)

After adding the ip to xhost, everything works. There is no need to downgrade Xquartz version.

Turns out there's a bug in XQuartz 2.7.9.

When using XQuartz 2.7.10_beta2, it works.