How to test if Xvfb is working?

[Foorcee]

I'm trying to check that Xvfb is working correctly, but when I try to take a screenshot the whole image is black.
Is taking screenshots supported with Xvfb?

[3arthqu4ke]

It seems weird to me that the screenshot would not be working with xvfb. Are you sure you are not also running the game with the lwjgl flag?

[Foorcee]

Actually, I'm pretty sure I haven't set that flag. I started HeadlessMC in Docker, following the actions from Mc-Runtime-Test as a reference.

I ran into an issue when using xvfb-run as the ENTRYPOINT - nothing happens, the game doesn't start, and I get no output at all. After some searching, I ended up using the following startup script:

#!/bin/bash
Xvfb :99 -ac -screen 0 "$XVFB_RES" -nolisten tcp $XVFB_ARGS &
XVFB_PROC=$!
sleep 1
export DISPLAY=:99
"$@"
kill $XVFB_PROC

With this setup, I get the following output when launching:

The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Could not resolve keysym XF86CameraAccessEnable
> Warning:          Could not resolve keysym XF86CameraAccessDisable
...
Errors from xkbcomp are not fatal to the X server
[13:15:14] [main/WARNING] [Main]: Not running from the headlessmc-launcher-wrapper. No plugin support and in-memory launching.
Launching version fabric-loader-0.16.10-1.21.4, c9732635-8a76-4cfd-94d9-d333f9880e25
[13:15:14] [main/INFO] [XvfbService]: Running with xvfb
[13:15:14] [main/INFO] [LaunchOptions]: You are offline but running with xvfb, not using headless mode.
...
[13:15:20] [main/INFO]: Loading Minecraft 1.21.4 with Fabric Loader 0.16.10

My Dockerfile:

FROM eclipse-temurin:21 AS headlessmc

RUN apt-get update && \
    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
        xvfb x11-xserver-utils x11-xkb-utils && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

ARG HEADLESSMC_VER=2.5.0
ARG MINECRAFT_VER=1.21.4
ARG MOD_LOADER=fabric

RUN mkdir -p HeadlessMC run/mods
RUN echo "hmc.java.versions=$JAVA_HOME/bin/java\n\
hmc.gamedir=$PWD/run\n\
hmc.offline=true\n\
hmc.rethrow.launch.exceptions=true\n\
hmc.assets.dummy=false\n\
hmc.exit.on.failed.command=true" > HeadlessMC/config.properties

#Download Headless MC Release
RUN curl -L -o headlessmc-launcher.jar https://github.com/3arthqu4ke/headlessmc/releases/download/${HEADLESSMC_VER}/headlessmc-launcher-${HEADLESSMC_VER}.jar

#Download Minecraft
RUN java -jar headlessmc-launcher.jar --command download ${MINECRAFT_VER}
RUN java -jar headlessmc-launcher.jar --command ${MOD_LOADER} ${MINECRAFT_VER} --java 21

RUN echo -e "onboardAccessibility:false\n\
    pauseOnLostFocus:false" > run/options.txt

RUN java -jar headlessmc-launcher.jar --command launch fabric-loader-0.16.10-$MINECRAFT_VER -prepare --jvm -Djava.awt.headless=true

###

COPY xvfb-startup.sh xvfb-startup.sh
RUN sed -i 's/\r$//' xvfb-startup.sh
ARG RESOLUTION="1920x1080x24"
ENV XVFB_RES="${RESOLUTION}"
ARG XARGS=""
ENV XVFB_ARGS="${XARGS}"

ENTRYPOINT ["/bin/bash", "xvfb-startup.sh", "java", "-Dhmc.check.xvfb=true", "-jar", "headlessmc-launcher.jar", "--command", "launch", "fabric-loader-0.16.10-1.21.4", "--regex"]

As far as I can tell, there isn't an official Docker image that includes Xvfb. If you have one, I'd appreciate it!

[3arthqu4ke]

#249

Might be interesting for you.