Indeed, I am currently working on unattended Ubuntu Server 18.04 installation:

1. deploying ubuntu server;
2. updating hostname which is fetched from a local web service;
3. changing password for a fixed user which is also fetched from a local web service;
4. running installation script (apt-get install; pip install; and adjusting some unique per host configurations)

I am able to deploy ubuntu server, contact the local web service to generate hostnames and passwords using postdownload scripts, yet I am not able to change the password and the hostname, nor I am not able to do some final installations.

I assume that it is done by specifying the snapins, yet my /bin/bash snapin is queued, but not executed.

I’ve created a simple snapin

#!/bin/bash

echo "Snapin BLAH BLAH beginning installation" > %systemdrive%\fog_snapin_install_snapinname.log
echo "test" > /home/user/test.txt
echo "Snapin BLAH BLAH ending installation" > %systemdrive%\fog_snapin_install_snapinname.log

I believe by being able to finish my small project I would be able to showcase something also for Linux users.

EDIT: of course I have just noticed that in order to use snapins one must install fog client on the host machine.

So my question would rather be “How do you run a script after the first boot using the deployed host OS without installing FOG Client?”