how did docker slime support centos xrdp desktop?

[fjibj]

Expected Behavior

I build a centos-xrdp image (https://github.com/feifeixj/docker-centos7-xrdp-english) for remote access, it's so big, 5.11GB. so I want to shim it, and I expect the shimed one would work round

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Actual Behavior

but it's not. When I remote access the container, it only show me a black screen.
I check the progress,

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Steps to Reproduce the Problem

1. docker-slim build --dockerfile Dockerfile --tag dcx --http-probe-off .
   output:
   docker-slim: message='join the Gitter channel to ask questions or to share your feedback' info='https://gitter.im/docker-slim/community'
   docker-slim: message='join the Discord server to ask questions or to share your feedback' info='https://discord.gg/9tDyxYS'
   docker-slim: message='Github discussions' info='https://github.com/docker-slim/docker-slim/discussions'
   cmd=build info=exec message='changing continue-after from probe to nothing because http-probe is disabled'
   cmd=build info=exec message='changing continue-after to enter'
   cmd=build state=started
   cmd=build info=params context='.' file='Dockerfile' continue.mode='enter' rt.as.user='true' keep.perms='true' target.type='dockerfile'
   cmd=build state=building message="building basic image"
   cmd=build info=basic.image.info tag='dcx.fat' dockerfile='Dockerfile' context='.'
   cmd=build state=basic.image.build.completed
   cmd=build state=image.inspection.start
   cmd=build info=image id='sha256:c4e7fbd54351878a959a8f9522699abebaf6c1c837428acea723c5f126494dcc' size.bytes='5106643379' size.human='5.1 GB'
   cmd=build info=image.stack name='centos:7' id='sha256:eeb6ee3f44bd0b5103bb561b4c16bcb82328cfe5809ab675bb17ab3a16c517c9' index='0'
   cmd=build info=image.stack index='1' name='dcx.fat:latest' id='sha256:c4e7fbd54351878a959a8f9522699abebaf6c1c837428acea723c5f126494dcc'
   cmd=build info=image.exposed_ports list='3389'
   cmd=build state=image.inspection.done
   cmd=build state=container.inspection.start
   cmd=build info=container status='created' name='dockerslimk_16211_20220422060812' id='709828c03fc3051d5cdba40f000d6412ae57a1f2412ec89ae5f1b32757866bd9'
   cmd=build info=container id='709828c03fc3051d5cdba40f000d6412ae57a1f2412ec89ae5f1b32757866bd9' status='running' name='dockerslimk_16211_20220422060812'
   cmd=build info=container message='obtained IP address' ip='172.17.0.5'
   cmd=build info=cmd.startmonitor status='sent'
   cmd=build info=event.startmonitor.done status='received'
   cmd=build info=container id='709828c03fc3051d5cdba40f000d6412ae57a1f2412ec89ae5f1b32757866bd9' target.port.list='49236' target.port.info='3389/tcp => 0.0.0.0:49236' message='YOU CAN USE THESE PORTS TO INTERACT WITH THE CONTAINER' name='dockerslimk_16211_20220422060812'
   cmd=build info=continue.after mode='enter' message='provide the expected input to allow the container inspector to continue its execution'
   cmd=build prompt='USER INPUT REQUIRED, PRESS WHEN YOU ARE DONE USING THE CONTAINER'

2. on my win10, use "mstsc" to open a remote access windows, input xx.xx.xx.xx:49236 and click "connect", after enter username and password (user/user), it show me a totally black screen.

3. docker exec -it dockerslimk_16211_20220422060812 /bin/bash
   [root@709828c03fc3 /]# ps -ef
   UID PID PPID C STIME TTY TIME CMD
   root 1 0 6 14:08 ? 00:00:32 /opt/dockerslim/bin/docker-slim-sensor -log-l
   root 16 1 0 14:08 ? 00:00:00 /usr/bin/python /usr/bin/supervisord -n -c /e
   root 37 16 0 14:08 ? 00:00:00 /sbin/xrdp-sesman -n
   root 38 16 0 14:08 ? 00:00:00 /sbin/xrdp -n
   root 39 38 0 14:09 ? 00:00:00 [xrdp]
   root 40 38 0 14:09 ? 00:00:00 [xrdp]
   root 41 37 0 14:09 ? 00:00:00 /sbin/xrdp-sesman -n
   user 42 41 0 14:09 ? 00:00:00 /bin/bash -l /usr/libexec/xrdp/startwm-bash.s
   user 43 41 1 14:09 ? 00:00:04 Xvnc :10 -auth .Xauthority -geometry 1280x720
   user 50 41 0 14:09 ? 00:00:00 /usr/sbin/xrdp-chansrv
   user 83 42 0 14:09 ? 00:00:00 xrdb -nocpp -merge /etc/X11/Xresources
   root 84 38 0 14:14 ? 00:00:00 [xrdp]
   root 85 38 0 14:14 ? 00:00:00 /sbin/xrdp -n
   user 86 37 0 14:16 ? 00:00:00 [reconnectwm.sh]
   root 87 0 0 14:16 pts/0 00:00:00 /bin/bash
   root 105 87 0 14:16 pts/0 00:00:00 ps -ef

compare with the container with original image:

docker exec -it aaa /bin/bash
[root@3a823e992a83 /]# ps -ef
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 11:39 ? 00:00:03 /usr/bin/python /usr/bin/supervisord -n -c /e
root 26 1 0 11:39 ? 00:00:00 /sbin/xrdp-sesman -n
root 27 1 0 11:39 ? 00:00:00 /sbin/xrdp -n
root 30 26 0 11:39 ? 00:00:00 /sbin/xrdp-sesman -n
user 31 30 0 11:39 ? 00:00:00 xfce4-session
user 32 30 0 11:39 ? 00:00:01 Xvnc :10 -auth .Xauthority -geometry 1280x720
user 39 30 0 11:39 ? 00:00:00 /usr/sbin/xrdp-chansrv
user 79 1 0 11:39 ? 00:00:00 dbus-launch --sh-syntax --exit-with-session
user 80 1 0 11:39 ? 00:00:00 /usr/bin/dbus-daemon --fork --print-pid 5 --p
user 96 31 0 11:39 ? 00:00:00 /usr/bin/ssh-agent /home/user/.Xclients
user 98 1 0 11:39 ? 00:00:00 ibus-daemon -drx
user 102 1 0 11:39 ? 00:00:00 /usr/libexec/gvfsd
user 106 1 0 11:39 ? 00:00:00 /usr/lib64/xfce4/xfconf/xfconfd
user 113 98 0 11:39 ? 00:00:00 /usr/libexec/ibus-dconf
user 114 98 0 11:39 ? 00:00:00 /usr/libexec/ibus-ui-gtk3
user 119 1 0 11:39 ? 00:00:00 /usr/libexec/ibus-x11 --kill-daemon
user 121 1 0 11:39 ? 00:00:00 /usr/libexec/ibus-portal
user 136 1 0 11:39 ? 00:00:00 /usr/libexec/at-spi-bus-launcher
user 141 136 0 11:39 ? 00:00:00 /usr/bin/dbus-daemon --config-file=/usr/share
user 143 1 0 11:39 ? 00:00:00 /usr/libexec/at-spi2-registryd --use-gnome-se
user 152 1 0 11:39 ? 00:00:00 /usr/libexec/dconf-service
user 156 98 0 11:39 ? 00:00:00 /usr/libexec/ibus-engine-simple
user 162 1 0 11:39 ? 00:00:00 /bin/gpg-agent --sh --daemon --write-env-file
user 164 1 0 11:39 ? 00:00:00 xfwm4
user 168 1 0 11:39 ? 00:00:00 xfce4-panel
user 170 1 0 11:39 ? 00:00:00 Thunar --daemon
user 172 1 0 11:39 ? 00:00:01 xfdesktop
user 173 1 0 11:39 ? 00:00:00 xfsettingsd
user 177 1 0 11:39 ? 00:00:00 xfce4-power-manager
user 191 1 0 11:39 ? 00:00:00 /usr/libexec/gvfs-udisks2-volume-monitor
user 201 102 0 11:39 ? 00:00:00 /usr/libexec/gvfsd-trash --spawner :1.2 /org/
user 207 1 0 11:39 ? 00:00:00 /usr/libexec/gvfsd-metadata
user 212 168 0 11:39 ? 00:00:00 /usr/lib64/xfce4/panel/wrapper-1.0 /usr/lib64
user 213 168 0 11:39 ? 00:00:00 /usr/lib64/xfce4/panel/wrapper-1.0 /usr/lib64
user 219 1 0 11:39 ? 00:00:00 /bin/xfce4-terminal
user 223 219 0 11:39 ? 00:00:00 gnome-pty-helper
user 224 219 0 11:39 pts/0 00:00:00 bash
root 255 0 8 14:20 pts/1 00:00:00 /bin/bash
root 274 255 0 14:20 pts/1 00:00:00 ps -ef

so the shim container has no desktop process (xfce, etc.) started. why and how to solve this question?

Specifications

• Version: docker-slim version
  cmd=version info=app version='linux|Transformer|1.37.5|86fbd29ab3549fa564e87e4770178480cb0542
• Platform: # docker version
  Client: Docker Engine - Community
  Version: 20.10.14
  API version: 1.41
  Go version: go1.16.15