VNC desktop - Microsandbox

<Tooltip tip="This example publishes noVNC to a port on the computer running the CLI, which is not available on microsandbox cloud."><span className="msb-badge-local">Local-only <Icon icon="circle-info" size={11} /></span></Tooltip>

VNC does not require a physical display or GPU. TigerVNC's X server draws into a virtual framebuffer in guest memory, encodes changed regions, and sends them to the client. noVNC provides the browser client over WebSockets.

This example runs the lightweight LXQt desktop with Breeze styling and opens QTerminal. It is useful for GUI-only utilities, observing browser sessions, and testing desktop applications—not for graphics-performance workloads.

Run the desktop

Save the desktop setup and service lifecycle in a host-side script:

#!/bin/sh
set -eu

apt-get update
DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
  breeze-icon-theme ca-certificates dbus-x11 lxqt-core novnc openbox \
  qterminal tigervnc-standalone-server websockify
rm -rf /var/lib/apt/lists/*

mkdir -p /root/.config/lxqt /root/.config/openbox /tmp/runtime-root
chmod 700 /tmp/runtime-root
sed -e "s/,quicklaunch//" -e "/^\[quicklaunch\]/,/^$/d" \
  /usr/share/lxqt/panel.conf > /root/.config/lxqt/panel.conf
sed "s#<name>Clearlooks</name>#<name>Breeze-ob</name>#" \
  /etc/xdg/openbox/rc.xml > /root/.config/openbox/rc.xml

Xtigervnc :1 -SecurityTypes None -geometry 1440x900 -depth 24 >/tmp/xvnc.log 2>&1 &
vnc_pid=$!
sleep 2
if ! kill -0 "$vnc_pid"; then
  cat /tmp/xvnc.log >&2
  exit 1
fi
cat /tmp/xvnc.log

DISPLAY=:1 XDG_RUNTIME_DIR=/tmp/runtime-root \
  dbus-launch --exit-with-session sh -c "
    startlxqt &
    session_pid=\$!
    sleep 4
    kill -0 \"\$session_pid\"
    qterminal &
    wait \"\$session_pid\"
  " >/tmp/lxqt.log 2>&1 &
desktop_pid=$!
sleep 5
if ! kill -0 "$desktop_pid"; then
  cat /tmp/lxqt.log >&2
  exit 1
fi

exec websockify --web=/usr/share/novnc 0.0.0.0:6080 localhost:5901

--script-path installs this file as the executable start-desktop command inside the guest.

</Step> <Step title="Start the desktop"> <CodeGroup> ```sh macOS & Linux msb run -d --name vnc-desktop --replace \ --cpus 2 --memory 2G --root-disk 5G \ -p 127.0.0.1:6080:6080 \ --script-path start-desktop:./start-desktop.sh \ --entrypoint start-desktop \ debian:bookworm-slim ```

powershell

msb run -d --name vnc-desktop --replace `
  --cpus 2 --memory 2G --root-disk 5G `
  -p 127.0.0.1:6080:6080 `
  --script-path start-desktop:./start-desktop.sh `
  --entrypoint start-desktop `
  debian:bookworm-slim

</CodeGroup>

Detached mode returns as soon as the VM starts, before the desktop packages are ready. The first install downloads about 183 MB, uses roughly 734 MB of guest disk, and can take a few minutes. Follow the installation, TigerVNC startup, and websockify output:

msb logs -f vnc-desktop

When websockify reports that it is listening, press Ctrl-C to stop following the log. The sandbox keeps running. Confirm that noVNC is serving HTTP:

<CodeGroup> ```sh macOS & Linux curl -fsS http://127.0.0.1:6080/vnc.html >/dev/null && echo "noVNC is ready" ```

powershell

curl.exe -fsS http://127.0.0.1:6080/vnc.html *> $null
if ($LASTEXITCODE -ne 0) { throw 'noVNC is not ready' }
'noVNC is ready'

</CodeGroup>

Open http://127.0.0.1:6080/vnc.html?autoconnect=1&resize=scale. You should see an LXQt desktop with QTerminal open.

</Step> <Step title="Verify the services">

Check the browser endpoint from the host:

<CodeGroup> ```sh macOS & Linux curl -sS http://127.0.0.1:6080/vnc.html | head ```

powershell

curl.exe -sS http://127.0.0.1:6080/vnc.html | Select-Object -First 10

</CodeGroup>

Then inspect the VNC server log inside the guest:

msb exec vnc-desktop -- sh -lc 'grep -E "Listening|created VNC server" /tmp/xvnc.log'

<Warning> VNC authentication is disabled inside this VM. The host listener is therefore intentionally restricted to `127.0.0.1`. Do not publish port 6080 on a LAN or public interface without VNC authentication, TLS, and an authenticated reverse proxy. </Warning> </Step> <Step title="Clean up"> <CodeGroup> ```sh macOS & Linux msb rm -f vnc-desktop rm -f start-desktop.sh ```

powershell

msb rm -f vnc-desktop
Remove-Item start-desktop.sh

</CodeGroup>

For repeated launches, stop the prepared sandbox, create a snapshot, and boot desktops from that snapshot instead of reinstalling the packages.

</Step> </Steps>