X11 Display variable is not set - can't run Docker Image - linux

Question

i made a Docker-Image of JMeter because I want to run it remote (and from a cloud). If I run the Image I am getting the error: 'No X11 DISPLAY variable was set, but this program performed an operation which requires it.'
I've updated the ssh_config file and the sshd_config file (as mentioned in similiar questions) but it still don't work.
And my DISPLAY variable is set to localhost:10.0. It's maybe useful to know that i am doing this on a VM on Ubuntu 19.04.
Thanks for your help.

Answer 1

After a few hours searching I found the solution: (credit)
My setup is ubuntu 18.04, lxde, this docker build
I modified the run script like this:
#!/bin/bash
#
# Run JMeter Docker image with options
NAME="jmeter"
JMETER_VERSION=${JMETER_VERSION:-"5.4"}
IMAGE="justb4/jmeter:${JMETER_VERSION}"
# Finally run
xhost +
docker run -e DISPLAY=$DISPLAY --rm --name ${NAME} -i -v ${PWD}:${PWD} -v /tmp/.X11-unix:/tmp/.X11-unix:ro -w ${PWD} ${IMAGE} $#
xhost -
this work, by term of effort it's much less than another method (vnc...)

Answer 2

You should declare this DISPLAY variable using ENV command like:
ENV DISPLAY :10
But be aware that you need to have a display server, at least Xvfb.
So running JMeter GUI in Docker container is possible, but you will have to treat it like a normal Linux desktop, it can be a minimal one like Xfce
Example Dockerfile which downloads latest JMeter, installs virtual desktop and makes it available via VNC and RDP
FROM alpine:edge
ENV DISPLAY :99
ENV RESOLUTION 1366x768x24
RUN echo "http://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories \
&& apk add --no-cache curl xfce4-terminal xvfb x11vnc xfce4 openjdk8-jre bash xrdp \
&& curl -L https://archive.apache.org/dist/jmeter/binaries/apache-jmeter-5.1.1.tgz > /tmp/jmeter.tgz \
&& tar -xvf /tmp/jmeter.tgz -C /opt \
&& rm /tmp/jmeter.tgz \
&& curl -L https://jmeter-plugins.org/get/ > /opt/apache-jmeter-5.1.1/lib/ext/jmeter-plugins-manager.jar \
&& echo "[Globals]" > /etc/xrdp/xrdp.ini \
&& echo "bitmap_cache=true" >> /etc/xrdp/xrdp.ini \
&& echo "bitmap_compression=true" >> /etc/xrdp/xrdp.ini \
&& echo "autorun=jmeter" >> /etc/xrdp/xrdp.ini \
&& echo "[jmeter]" >> /etc/xrdp/xrdp.ini \
&& echo "name=jmeter" >> /etc/xrdp/xrdp.ini \
&& echo "lib=libvnc.so" >> /etc/xrdp/xrdp.ini \
&& echo "ip=localhost" >> /etc/xrdp/xrdp.ini \
&& echo "port=5900" >> /etc/xrdp/xrdp.ini \
&& echo "username=jmeter" >> /etc/xrdp/xrdp.ini \
&& echo "password=" >> /etc/xrdp/xrdp.ini
EXPOSE 5900
EXPOSE 3389
CMD ["bash", "-c", "rm -f /tmp/.X99-lock && rm -f /var/run/xrdp.pid\
&& nohup bash -c \"/usr/bin/Xvfb :99 -screen 0 ${RESOLUTION} -ac +extension GLX +render -noreset && export DISPLAY=99 > /dev/null 2>&1 &\"\
&& nohup bash -c \"startxfce4 > /dev/null 2>&1 &\"\
&& nohup bash -c \"x11vnc -xkb -noxrecord -noxfixes -noxdamage -display :99 -forever -bg -nopw -rfbport 5900 > /dev/null 2>&1\"\
&& nohup bash -c \"xrdp > /dev/null 2>&1\"\
&& nohup bash -c \"/opt/apache-jmeter-5.1.1/bin/./jmeter -Jjmeter.laf=CrossPlatform > /dev/null 2>&1 &\"\
&& tail -f /dev/null"]
You can build it like:
docker build -t jmeter.
and once done kick off the container using Docker run command like:
docker run -p 5900:5900 -p 3389:3389 jmeter
You might also find Make Use of Docker with JMeter - Learn How guide useful.

Answer 3

there is NO solution for Docker-Images. Because Docker does not support GUI and therefore i am getting this error. So if you are working with Docker and you are getting this error, just ignore it or update your image to only non-gui.
Cheers