Ssh – How to use nohup properly within an ssh session invoked by gitlab-runner

I use gitlab runner's ssh executor to access an embedded device via ssh. I want to run a script there.

Basically the script invokes an upgrade routine on the device using dbus. Simple enough, isn't it?

#!/bin/bash
dbus-send --session --print-reply --dest=blabla /path blabla.swupdate.InitiateUpdate string:"" string:"" string:"$1"
sleep 4
dbus-send --session --print-reply --dest=--dest=blabla /path blabla.UpgradeMode

Now the device will immediately reboot, causing the ssh connection with gitlab runner to terminate unexpectedly, which leads to a pipeline failure.

I came up which various script entries to detach the last dbus call from the ssh connection but to no avail.

Here is one thing I tried:

#!/bin/bash
dbus-send --session --print-reply --dest=blabla /path blabla.swupdate.InitiateUpdate string:"" string:"" string:"$1"
nohup $(sleep 2 && dbus-send --session --print-reply --dest=--dest=blabla /path blabla.UpgradeMode)&
echo "ready to disconnect ssh"

When I connect manually using ssh, executing the script and disconnect quickly manually using exit, I see the system reboot. But when gitlab-runner executes everything, the job succeeds, but the reboot does not happen. So I am sure that the nohup-command does not get fully executed.

I tried putting nohupin front of both the sleep and the dbus-send command, as well as trying to put disown after the parentheses. I also tried as suggested by a comment here, to put nohup in front of the script call in .gitlab-ci.yml.

None of that lead to success.

Any ideas, how to get this right?

Thanks