In normal use qubes are created on, and changes written to, the disk. There is also extensive logging and signs of the qube are scattered in a number of places.
Sometimes, you want to create a qube which does not leave these traces.
You can do this relatively simply, by creating a RAM based storage area and using it for a new storage pool.
The qube will persist until the RAM disk is deleted, or the machine is shut down.
A script like this in dom0, will create tmpfs RAM disk, create a new storage pool in that disk, and create a new qube using that pool.
tmp_qubes.sh:
#!/bin/bash
mkdir /home/user/tmp
sudo mount -t tmpfs -o size=2G new /home/user/tmp/
qvm-pool add -o revisions_to_keep=1 -o dir_path=/home/user/tmp/ newer file
qvm-create new -P newer -t debian-11 -l purple --property netvm=tor
qvm-run new firefox-esr
You can remove the qube, and some of the associated artifacts by script in dom0.
rmtmp_qube.sh:
#!/bin/bash
qvm-kill new
qvm-remove -f new
qvm-pool rm newer
sudo umount new
sudo rm -rf /home/user/tmp
sudo rm -rf /var/log/libvirt/libxl/new.log
sudo rm -rf /var/log/libvirt/libxl/new.log
sudo rm -rf /var/log/qubes/vm-new.log
sudo rm -rf /var/log/qubes/guid.new.log
sudo rm -rf /var/log/qubes/guid.new.log.old
sudo rm -rf /var/log/qubes/qrexec.new.log
sudo rm -rf /var/log/qubes/qubesdb.new.log
sudo rm -rf /var/log/qubesdb.new.log
sudo rm -rf /var/log/guid/new.log
sudo rm -rf /var/log/qrexec.new.log
sudo rm -rf /var/log/pacat.new.log
sudo rm -rf /var/log/xen/console/guest-new.log
None of this is forensically reliable, although it is better than using a standard pool. (Refer to this issue, particularly if you are using Xfce, and check the associated issues.)
There's an effort to remove most of the log references, although the stupidity of journalctl means that you'll have to wipe the journal if you want to delete references there.
As this method uses tmpfs, it's possible that it may swap out. If you want to avoid this I suggest disabling swap - sudo swapoff -a - before running tmp_qubes.sh. You could always put this as line 2 of the script.
Also, the scripts themselves will be on the disk, which may require some explanation.