Dear Future Self,
You have probably started to install a CentOS Stream 9 cloud image, and completely forgot all the things you learned this time around. No worries, past-self is going to write these down for your usage.
First off, download the image you want. On the day we are writing this, the latest image is http://cloud.centos.org/centos/9-stream/x86_64/images/CentOS-Stream-GenericCloud-9-20220207.0.x86_64.qcow2 but it will most likely be something much newer. They don't put a 'latest' in the directory, so open a browser, search for qcow2, and then instead of searching through 4000 entries from 2021-08-30, press the up-arrow and jump to the last entry on the web-page.
Next, we need to use virt-install to get the image imported to where virtual manager will use it. Older versions of CentOS had a default user, but CentOS Stream 9 relies on cloud-init in order set up the root user and password. This is done via the virt-install command IF you have a virt-install after version 3, so need to look at different command for EL8 and Ubuntu 18.
$ sudo virt-install --name guest-cs9 --memory 2048 \ --vcpus 2 --disk ./CentOS-Stream-GenericCloud-9-20220207.0.x86_64.qcow2 \ --import --os-type Linux --os-variant centos-stream9 \ --network default --console pty,target_type=serial --graphics vnc \ --cloud-init root-password-generate=on,disable=on,ssh-key=/home/ssmoogen/.ssh/id_ecdsa.pub
You can add more cloud init options by creating data-files for meta and user-data. Go to the cloud-init site for that.
Alternative method (ok the one most likely used).
In the case of trying to do this on EL8 or earlier Ubuntu editions, you will need to use the virt-customize command instead. First we have to make sure it is installed.
For Ubuntu:$ sudo apt install libguestfs-toolsFor EL based distros:$ sudo dnf install guestfs-tools
The virt-customize command is meant to alter a non-running image. If you use it on a running one, you will probably have a very dead box afterwards. YOU HAVE BEEN WARNED.
Depending on the OS this may or may not need to be run with sudo. Check the CSG.out file for any extra errors. We sent both standard out and standard error there to make sure it all got captured. After this is done, you can import as working image with:$ virt-customize -v --uninstall cloud-init --selinux-relabel \ -a CentOS-Stream-GenericCloud-9-20220207.0.x86_64.qcow2 \ --ssh-inject root:file:/home/ssmoogen/.ssh/id_ecdsa.pub \ --root-password random |& tee CSG.out $ grep 'virt-customize.password' CSG.out # for the random set password.
$ sudo virt-install --name guest-cs9 --memory 2048 \ --vcpus 2 --disk ./CentOS-Stream-GenericCloud-9-20220207.0.x86_64.qcow2 \ --import --os-type Linux --os-variant centos-stream9 \ --network default --console pty,target_type=serial --graphics vnc
And with that, past self is done recording what is needed to be done.