Deb: provide an easy way to start KasmVNC with default options

...via kasmvncserver-start.

builder/dockerfile.debian_buster.barebones.deb.test

@@ -5,6 +5,8 @@ COPY $KASMVNC_PACKAGE_DIR/kasmvncserver_*.deb /tmp
 RUN apt-get update && dpkg -i /tmp/*.deb; apt-get -yf install
 RUN apt-get update && apt-get -y install xterm
 
+COPY startup/deb/kasmvncserver-start /usr/local/bin
+
 RUN useradd -m foo
 
 USER foo:ssl-cert
@@ -12,4 +14,4 @@ USER foo:ssl-cert
 RUN mkdir ~/.vnc && echo '/usr/bin/xterm &' >> ~/.vnc/xstartup && \
   chmod +x ~/.vnc/xstartup
 
-ENTRYPOINT bash -c "echo -e \"$VNC_PW\n$VNC_PW\n\" | kasmvncpasswd -w -u $VNC_USER $HOME/.kasmpasswd && vncserver :1 -interface 0.0.0.0 && vncserver -kill :1 && vncserver :1 -depth 24 -geometry 1280x1050 -websocketPort 8443 -cert /etc/ssl/certs/ssl-cert-snakeoil.pem -key /etc/ssl/private/ssl-cert-snakeoil.key -sslOnly -FrameRate=24 -interface 0.0.0.0 -httpd /usr/share/kasmvnc/www && tail -f $HOME/.vnc/*.log "
+ENTRYPOINT bash -c "echo -e \"$VNC_PW\n$VNC_PW\n\" | kasmvncpasswd -w -u $VNC_USER $HOME/.kasmpasswd && kasmvncserver-start && tail -f $HOME/.vnc/*.log "

builder/startup/deb/kasmvncserver-start

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+set -e
+
+display=:1
+interface=0.0.0.0
+cert_group=ssl-cert
+
+if groups | grep -qvw ssl-cert; then
+  cat <<-EOF
+    Can't access TLS certificate.
+    Please add your user to $cert_group via 'addgroup <user> ssl-cert'
+EOF
+  exit 1
+fi
+
+vncserver $display -interface $interface
+vncserver -kill $display
+vncserver $display -depth 24 -geometry 1280x1050 -websocketPort 8443 \
+  -cert /etc/ssl/certs/ssl-cert-snakeoil.pem \
+  -key /etc/ssl/private/ssl-cert-snakeoil.key -sslOnly -FrameRate=24 \
+  -interface $interface -httpd /usr/share/kasmvnc/www