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Asked: 2024-09-27T00:16:30+05:30 In: ,

How can I execute a basic X11 application within a Docker container on Ubuntu 20.04?

I’ve been trying to figure out how to run a basic X11 application inside a Docker container on my Ubuntu 20.04 setup, and it’s becoming quite the rabbit hole! I want to load up something simple, like `xeyes` or `xclock`, just to see that everything is working as expected before diving into more complex apps.

So, I’ve set up Docker and it seems to be running fine. The thing is, I really want the GUI of the application to show up so I can use it just like I normally would outside of Docker. I’ve tried a few different things, but none of them seem to fully work. The closest I got was running `xeyes` and getting a bunch of errors related to display.

I’ve read somewhere that I need to configure my X11 settings to allow access from the Docker container, and I think it has to do with the DISPLAY variable and potentially using `xhost` to enable connections. But I’m not entirely sure how to piece all of this together. Like, do I need to run `xhost +local:` before I start the container? And then, once I’m in the container, how exactly do I set up the DISPLAY variable? Is it as simple as just setting it to `:0`?

Furthermore, I’m unsure if I need to mount anything special from the host into the container when I run it, maybe something with `/tmp/.X11-unix`? It seems like there’s a lot of steps involved, and I’d hate to mess something up.

If anyone has a clear, step-by-step approach or can point out what I’ve missed, that would be awesome. I’ve seen a few tutorials online, but they tend to gloss over some of the specifics, and I end up more confused than when I started! Let me know how you guys have gone about this, especially if you’ve hit any snags along the way. Thanks for any help!

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    2 Answers

    1. To run a basic X11 application like xeyes or xclock inside a Docker container on your Ubuntu 20.04 setup, you’ll need to ensure that X11 forwarding is properly configured. Start by allowing local connections to your X server using the command xhost +local:. This will grant the Docker container permission to access your display. Next, when you create and run your Docker container, you should specify the DISPLAY variable and mount the X11 socket. You can achieve this with a command like the following:

              docker run -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix -it your-docker-image

      Inside the container, you may need to set the DISPLAY variable explicitly to :0 if it isn’t properly set. This tells the application where to render the GUI. If you encounter any permission issues or still get errors, ensure that your user inside the container has the necessary rights to access the X server. In some cases, you may also need to install dependencies such as x11-apps inside the container using apt-get to ensure applications like xeyes or xclock are available. Follow these steps, and you should see the GUI applications showing up as intended.



    2. Running X11 Applications in Docker

      Running X11 Applications like xeyes or xclock in Docker

      Here’s a simple step-by-step guide to help you run a basic X11 application inside a Docker container. This should make it a bit easier to set things up!

      Step 1: Allow Access to X11

      First, you need to allow Docker to access your X11 server. Run this command in your terminal:

      xhost +local:

      This allows local connections. It’s pretty important!

      Step 2: Run Your Docker Container

      When you’re ready to run your Docker container, you need to set up a few things. Here’s a sample command you can use:

      
docker run -it \
    --env DISPLAY=$DISPLAY \
    --volume /tmp/.X11-unix:/tmp/.X11-unix \
    YOUR_DOCKER_IMAGE_NAME

      Make sure to replace YOUR_DOCKER_IMAGE_NAME with the name of your image.

      Step 3: Setting DISPLAY Variable in the Container

      Inside your Docker container, you can check if the DISPLAY variable is set correctly by running:

      echo $DISPLAY

      If you see something like :0, you’re good to go!

      Step 4: Running xeyes or xclock

      Now, you can simply run xeyes or xclock inside your container:

      xeyes

      After you run that, you should see the GUI pop up on your host machine!

      Troubleshooting Tips

      • If you run into errors, double-check that xhost command was run before starting your container.
      • Make sure you have the necessary X11 libraries installed in your Docker image.
      • Also, check that your Docker image is set up to run graphical applications.

      Security Note

      Using xhost +local: opens up your X server to all local users. If you’re concerned about security, consider restricting access later by running xhost -local: after you’re done using the GUI apps.

      Hope that helps! It can be a little tricky, but it’s totally doable. Good luck with your Docker X11 adventures!


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