Is there any reason why xvfb-run will not be executed as docker overridden command?
Having an image from this Dockerfile:
FROM ubuntu:20.04
RUN apt-get update && apt-get install -y xvfb
Built with:
docker build -f Dockerfile.xvfb -t xvfb-test
If I execute a custom docker command with xfvb-run:
docker run xvfb-test bash -x /usr/bin/xvfb-run echo
It gets stuck and never ends
But, if I enter to the image docker run --rm -it xvfb-test bash, and execute the same command xvfb-run echo it finished immediately (meaning that the Xvfb server started and was able to execute the command)
This is an excerpt of xvfb-run script:
...
trap : USR1
(trap '' USR1; exec Xvfb ":$SERVERNUM" $XVFBARGS $LISTENTCP -auth $AUTHFILE >>"$ERRORFILE" 2>&1) &
XVFBPID=$!
wait || :
...
Executing with bash -x we can see what lines is the last that was executed:
+ XAUTHORITY=/tmp/xvfb-run.YwmHlq/Xauthority
+ xauth source -
+ trap : USR1
+ XVFBPID=16
+ wait
+ trap '' USR1
+ exec Xvfb :99 -screen 0 1280x1024x24 -nolisten tcp -auth /tmp/xvfb-run.YwmHlq/Xauthority
From this link
The docker --init option in the run command basically sets ENTRYPOINT to tini and passes the CMD to it or whatever you specify on the commandline. Without init, CMD becomes pid 1. In this case, /bin/bash
looks like running the command withouth init parameter, running as PID 1, is not handling the signal USR1 correctly.