NWS: Docker Reference

Go up to the main NWS readme (md)

Basic docker commands

Running a GUI from a docker container

Mac OS X

Note: this has only been tested on an ARM Mac (M1/M2), and not on an Intel x64 Mac. Reference: this article.

One-time installation

• If not installed, install Docker
  • Download and install the Mac version (appropriate for your architecture) of Docker from docker.com/download
  • Test Docker’s install via docker run hello-world – you should see an informative message
• Install homebrew, if not already installed
• Install socat via brew install socat
• Install xquartz via brew install xquartz
  • The first time xquartz launches, go do XQuartz -> Settings -> Security, and make sure “Allow connections from network clients” is checked

Running the GUI

• Make sure the docker engine is running – you should see a docker icon in the top bar (it looks like a container ship).
• Launch socat:
  • socat TCP-LISTEN:6000,reuseaddr,fork UNIX-CLIENT:\"$DISPLAY\"
  • You can put it in the background by appending & to it
• Run xquartz: open -a Xquartz
  • You have to log out and log back in to use Xquartz
• Make sure the value of the DISPLAY variable in docker-compose.yml is set to your IP (plus :0)
  • This is your IP on your local network: enter ifconfig en0 to find out what it is
  • Be sure to put the :0 at the end of the IP address
  • Example: DISPLAY=192.168.14.45:0 (with a - before it in the docker-compose.yml file)
  • You should change this, via find-and-replace, throughout the entire docker-compose.yml file
  • If you made a change to the docker-compose.yml file, restart the containers
• Connect to a docker container (any one), and run the gui program

Troubleshooting

• Most likely culprits: these seem to be the most common tips to get the GUI working
  • You may have to run xhost for your computer’s IP address (again, the one on en0, not localhost), especially if it’s the first time you are doing this, or if your IP address changed. You can run xhost + 1.2.3.4, where 1.2.3.4 is your en0 IP address. If it complains that xhost is not found, try entering the command with the full path to xhost: /opt/X11/bin/xhost + 1.2.3.4. You may have to execute this command each time you restart xquartz to run a GUI.
  • Make sure the IP address of your computer (on en0, not localhost) is set correctly throughout the docker-compose.yml file. If not, change it and then restart all the containers (docker compose down followed by docker compose up).
  • socat seems to work best when it is running before you start the docker containers. If you have already started the docker containers, and you either start (or restart) socat, you should restart all the containers (docker compose down followed by docker compose up).
  • In Xquartz, enter echo $DISPLAY. You will likely get something long-winded, like “/private/tmp/com.apple.launchd.NcQwxvwhxe/org.xquartz:0”. Look at the last two characters – in this example, it’s :0. If yours is a different number (such as :1), then you have change that throughout the docker-compose.yml file – change all instances of - DISPLAY=1.2.3.4:0 to - DISPLAY=1.2.3.4:1, where “1.2.3.4” is your IP address (for en0, not localhost), and :1 is the value you got from the last two characters of echo $DISPLAY in Xquartz. If you modify your docker-compose.yml file, you have to restart all the containers (docker compose down followed by docker compose up).
  • When connected in the docker container via docker exec, run echo $DISPLAY, and then export DISPLAY=1.2.3.4:0 where 1.2.3.4 is the IP of your machine (on your LAN), then try running the GUI program again. This will set the DISPLAY variable for that one container – if it’s different (meaning what you got from the echo command versus what you set with the export command), you should change it throughout docker-compose.yml, and then restart all the containers (docker compose down followed by docker compose up).
• Setup configuration: these are steps that you may have missed in the setup
  • Did you log out and then log in after installing xquartz?
  • Does the Mac firewall allow socat (or socat1) to receive incoming network connections? This is configured in System Settings -> Network -> Firewall -> Options. You should see ‘socat’ (or, more likely, ‘socat1’) with a green ‘allow incomming connections’ next to it.
  • Did you do this step: the first time xquartz launches, go do XQuartz -> Settings -> Security, and make sure “Allow connections from network clients” is checked
• None of the above works!
  • If you can run the socat command, but open -a Xquartz does NOT open up a window, you will need to do a full reset and restart (but not a reinstall) of the three commands used:
  • Shut down socat: killall -9 socat and/or killall -9 socat1 (this may cause the xquartz window to suddenly appear)
  • Shut down xquartz via Command-Q
  • Make sure there are no processes listening to port 6000: lsof -i :6000; if there are, kill them (kill -9 <PID>, where <PID> is the process value in the second column)
  • Shut down the docker containers: docker compose down
  • Restart the Docker Engine – click on the icon in the title bar, and select “restart” (there is a dialog box that asks you to confirm this, and sometimes that dialog box is hidden)
  • Do the next three steps in this exact order:
    • Start up socat: socat TCP-LISTEN:6000,reuseaddr,fork UNIX-CLIENT:\"$DISPLAY\"
    • Start up the docker containers: docker compose up
    • Start up xquartz: open -a Xquartz
  • Connect to a docker container: docker exec -it nws-outer1 /bin/bash
  • Check the DISPLAY variable: echo $DISPLAY
    • It should be <IP>:0; if not, set it: export DISPLAY=111.222.333.444:0; change as necessary, and be sure to put the :0 at the end
  • Run a GUI command: xeyes

Shutting down

• From the XQuartz menu, click on “Quit X11”
• Terminate socat: killall -9 socat

Linux

This was tested on Ubuntu 22.04. Reference: this article, but not really this article.

One-time installation

• If not installed, install Docker
  • Download and install the Linux version of Docker from docker.com/download
  • Test Docker’s install via docker run hello-world – you should see an informative message
• Ensure xhost is already installed (it probably is) – run which xhost to check

Running the GUI

• Run xhost +local:docker on your host
• Make sure the value of the DISPLAY variable in docker-compose.yml is just :0
  • Example: DISPLAY=:0, with the - preceeding it
  • You should change this, via find-and-replace, throughout the entire docker-compose.yml file
  • If you made a change to the docker-compose.yml file, restart the containers
• Connect to a docker container (any one), and run the gui program

Shutting down

• You can remove the xhost permission (via xhost -local:docker), but it does not seem to be a security issue if you leave it as-is

Windows

Reference: none. Tested on Windows 10 Pro. Because of how WSL works, it is assumed that this will work on any recent version of Windows.

One-time installation

• If not installed, install WSL (Windows Subsystem for Linux).
  • You can select version 2 to install via wsl --set-default-version 2
  • The command to install it is wsl --install -d Ubuntu
  • If it hangs at 0% installation, try adding the --web-download flag: wsl --install -d Ubuntu --web-download
  • When tested, an error 0x80004002 occurred; the solution is here
  • You launch WSL by running wsl in the search box
• If not installed, install Docker
  • Download the Windows version from docker.com/download
    • Don’t try to install this through WSL!
  • During the installation, be sure to select the ‘enable WSL shortcut’ check box
  • Test Docker’s install via docker run hello-world – you should see an informative message
• In WSL, install the xhost program: sudo apt install x11-server-utils

Running the GUI

• Start the Docker engine – it’s the “Docker Desktop” entry in Programs
  • WSL can’t use docker unless this is running
• Launch WSL; all further commands in this part are in WSL
• From this point, the directions are the same as the “Running the GUI” directions in Linux, since WSL provides a Linux shell
• Download and install the Linux version of Docker from docker.com/download
  • Run xhost +local:docker on your host
  • Make sure the value of the DISPLAY variable in docker-compose.yml is just :0
    • Example: DISPLAY=:0, with the - preceeding it
    • You should change this, via find-and-replace, throughout the entire docker-compose.yml file
    • If you made a change to the docker-compose.yml file, restart the containers
  • Connect to a docker container (any one), and run the gui program, such as xeyes.

Troubleshooting

• Docker Desktop may go to sleep, for example if your entire computer goes to sleep. If it does, then docker will not work in WSL. Wake up Docker Desktop (or restart it) to be able to run the docker command in WSL.
• If you cannot get the display working in Docker, try running a GUI app, such as xeyes, from WSL. If that doesn’t work, then the Docker GUIs won’t (Docker sends the GUI to WSL). Try:
  • when docker is running the containers, there is a ‘docker’ image running – open that one, click on a container, and you can load up a shell that will allow GUIs
• If Docker doesn’t work from WSL, and gives a message such as, “the command ‘docker’ could not be found in this WSL2 distro”, then try going to Docker Engine, then go to Settings -> Resources -> WSL Integration, and make sure the switch for the distribution (such as “Ubuntu”) is set. Then restart WSL.

Shutting down

• Shut down the Docker Engine program
• In WSL, you can remove the xhost permission (via xhost -local:docker), but it does not seem to be a security issue if you leave it as-is
• Exit WSL if desired