This post briefly describes a setup used for performing UI-based testing of Bitsquare. It consists of a headless Debian server (physical, though it may perfectly be some virtual machine or even a container) which, on boot, automatically starts an X session and makes it available via VNC and X2Go (since there is no monitor to access the session on).
This setup allows to automatically start UI tests on boot and later connect to the graphical session if needed.
We start by installing a plain Debian Jessie setup with just root and a normal
user. We avoid the complete X.Org installation (with video card drivers and
hardware detection) on purpose, so to keep the system minimal we only select
the SSH server and base system profiles when asked, and we leave desktop
environment out.
Headless X
Once the new system has booted, we install the xserver-xorg-video-dummy
package, which provides an X server that can run completely headless:
# apt-get install xserver-xorg-video-dummy
We configure X to use this server with the following /etc/X11/xorg.conf file
(as described in Add Fake Display when No Monitor is Plugged In):
Section "Device"
Identifier "Configured Video Device"
Driver "dummy"
EndSection
Section "Monitor"
Identifier "Configured Monitor"
HorizSync 31.5-48.5
VertRefresh 50-70
EndSection
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1280x1024"
EndSubSection
EndSection
Please note that we have no desktop environment yet. The following command installs the base X.Org system (which will use the existing dummy server) and the i3 window manager (though you may choose something heavier like GNOME, KDE or XFCE):
# apt-get install xorg i3
Remote desktop support
Since there is no display manager too, X sessions need to be started with the
good old startx command. However that would still be of little use since
graphics are nowhere to be shown. That is no problem as long as we are
somehow able to access the graphical session remotely. VNC and X2Go are two
solutions for that, with the latter being more amenable to low bandwidth and
high latency links (thanks Eloi Rebes and Ramon Selga from guifi.net for
pointing me to this one!).
The following commands install one of the many VNC servers available in Debian and the X2Go package needed for serving an existing session (X2Go can also run new sessions, but we are not interested in this setup; also note that we need to add an external repository for X2Go server packages):
# apt-get install x11vnc # echo 'deb http://packages.x2go.org/debian jessie main' > /etc/apt/sources.list.d/local-x2go.list # apt-key adv --recv-keys --keyserver keys.gnupg.net E1F958385BFE2B6E # apt-get update # apt-get install x2godeskstopsharing
The following ~user/.xsession script for the user X session starts the VNC
server and the X2Go server along a terminal emulator and the i3 window
manager:
#!/bin/sh x11vnc -usepw -ncache -shared -forever & x2godesktopsharing --activate-desktop-sharing & x-terminal-emulator & exec i3
Remember to make the script executable:
$ chmod 0750 ~user/.xsession
Please note that the VNC server will listen on port 5900 with no encryption,
so it should only be used in trusted local networks. Otherwise use X2Go,
which is tunneled over SSH (that is why we selected the SSH server profile
above). You may also use -localhost and tunnel VNC over SSH, but it may get
really slow. Also note that the VNC server will ask for a password which you
should first write in ~user/.vnc/passwdfile (remember to make it unreadable to
others with chmod 0600 =~user/.vnc/passwdfile).
Automatic desktop on boot
Finally we want the user to automatically login on boot and start a desktop
session. Since Debian Jessie uses systemd by default, we create the
/etc/systemd/system/getty@tty1.service.d/autologin.conf unit file to start a
user login (as explained in Debian Jessie and autologin):
[Service] ExecStart= ExecStart=-/sbin/agetty --autologin user %I
Then we need to make the user login automatically start an X session if none
is running. This is easy to do, we just add the following line to
~user/.profile (as indicated in Start X after automatic login):
test -z "$DISPLAY" -a "$(tty)" = /dev/tty1 && exec startx
Now we can reboot the server and everything should start as expected (X server messages will be shown in the console).
Connecting remotely
To acces user's desktop session from a trusted local network you may use any
VNC client:
$ xtightvncviewer SERVER_ADDRESS
To access it using X2Go you may use x2goclient or the leaner pyhoca-cli:
$ pyhoca-cli --server SERVER_ADDRESS --username user -D user@:0 --share-mode 1