Running remote GUI applications on a docker container

Introduction

This wiki explains how to prepare a docker container to run GUI applications. In addition, the applications are available for remote usage, making it possible to install applications on a server and run them on your workstations.

X2Go makes possible this task, enabling you to enter the GUI of your container and use the GUI application remotely without the -X overhead on the network.

Fulfilling the dependencies

Creating a container with Ubuntu (from docker server shell)

From your docker server terminal, create the container with the following commands:

# Pull the ubuntu image
docker pull ubuntu
# Create the container
CONTAINER_NAME=my_container
sudo docker run -itd --name $CONTAINER_NAME -p 2222:22 ubuntu /bin/bash

The -p argument exposes port 22 of your container to port 2222 of your host. That means that you can access to port 22 of your container from your <hostip>:2222

The following steps require you enter to your container shell. To open it, go to the docker server and execute:

CONTAINER=my_container
docker exec -ti $CONTAINER /bin/bash

Creating a container with Ubuntu (from Portainer)

From Portainer, please, add a new container. You can follow the next images in order to get ready.

In the left sidebar, click on Containers and then on Add Container. It will display the following view:

Fill the form with the data shown in the picture:

Name: my_container
Image: ubuntu:latest
In Port mapping, map additional port and add 2222 on host and 22 on container. This will redirect the traffic from your server at port 2222 to the container to the port 22.
Command: /bin/bash
Console: Interactive & TTY

After deploying your container:

Click on Console:

You will need console access for the next steps.

Install SSH

You need to be able to connect to your container through SSH. As a first step, install SSH:

apt update
apt install sudo ssh

Warning: The SSH service will not start on container boot. You need to create an entrypoint to get it on start up. If you want to start SSH manually, you can use:

service ssh start

Create an user

The next step is to create a user for remote access. Please, take a look at the following commands:

USERNAME=myusername
adduser $USERNAME

It will ask you for entering your password and other details. Fill the fields and, then, make it a sudoer:

usermod -aG sudo $USERNAME

Install a graphic desktop to your container

X2Go makes it possible to access a GUI installed in the container. However, the most common Ubuntu images do not have a graphical desktop installed by default. In this case, we recommend XFCE due to its lightweight.

sudo apt-get install -y xfce4

Install X2Go

Please, type the following commands to install X2Go server:

sudo apt-get install software-properties-common -y
sudo add-apt-repository ppa:x2go/stable
sudo apt-get update
sudo apt-get install x2goserver x2goserver-xsession -y

Make sure that SSH server is running. Check it running:

service ssh status

It should show:

● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enab
   Active: active (running) since jue 2019-08-08 13:27:58 CST; 1 day 1h ago
  Process: 5709 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCES
  Process: 5703 ExecReload=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
 Main PID: 1196 (sshd)
   CGroup: /system.slice/ssh.service
           └─1196 /usr/sbin/sshd -D

It is currently "active".

Accessing to your container with X2Go client

X2Go requires you to install a client on the host(local computer). Please, install in your client X2Go Client:

sudo apt install x2goclient 
# Run
x2goclient

After installing the client, create a new session:

Then, fill the form which opens after clicking the highlighted icon:

In Your machine name, type a personalized name for your session. In Container IP, type the IP of the container to access with X2Go. Also, type your username and select the Session Type with the Graphical Desktop which you installed in the container. In our case, it is XFCE.

After registering the new, in the X2go client window will appear a sidebar on the right with your session:

Double click your session and enter the container's password in the modal window.

Result

After entering your credentials, a new window will appear with your container GUI. In our case, it is the XFCE desktop:

Possible issues

There are elements that can cause issues with your X2Go client.

SSH is down: remember to start the SSH service. You can do it from your container shell with sudo service ssh start
Container is not connected to a bridge network. It is important to connect the container to a bridge network. If you cannot get access to the bridge network, you can show port 22 by port mapping when creating your container.

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