Table of Contents
New KVM Setup Guide
This is a guide on how to set up a new KVM image on a Ubuntu KVM installation.
The other way which might be much simpler would be to mount an ISO, but if you want to do it programmatically follow this article.
The steps required are:
- Generate cidata.iso file composed of `user-data` and `meta-data`
- Download the appropriate Cloud Image
- Convert the Cloud Image to a raw file
- Generate an new .img file that will be become your actual VM
- Install the VM
In the examples below, we assume you want to set up a new host called host1.example.com
It’s best to perform this work in a good working directory, e.g.:
cd /var/lib/libvirt/images
Just be super careful because this is where all your VM disks are stored and you don’t want anything to go wrong.
Generate cidata.iso file
We’ve listed this first because it’s the most complicated and getting anything wrong means you’ll have a non-working VM, e.g., difficulty logging in a root.
Ubuntu compatible user-data:
user-data
#cloud-config hostname: host1 fqdn: host1.example.com manage_etc_hosts: true users: - name: ubuntu sudo: ALL=(ALL) NOPASSWD:ALL groups: users, admin home: /home/ubuntu shell: /bin/bash lock_passwd: false ssh-authorized-keys: - <sshPUBKEY> # only cert auth via ssh (console access can still login) ssh_pwauth: false disable_root: false chpasswd: list: | ubuntu:linux expire: False package_update: true packages: - qemu-guest-agent write_files: - path: /etc/cloud/cloud.cfg.d/99-custom-networking.cfg permissions: '0644' content: | network: {config: disabled} - path: /etc/netplan/my-new-config.yaml permissions: '0644' content: | network: version: 2 ethernets: ens3: addresses: - A.B.C.D/24 nameservers: search: [example.com] addresses: [1.1.1.1, 8.8.4.4] routes: - to: default via: E.F.G.H runcmd: - rm /etc/netplan/50-cloud-init.yaml - netplan generate - netplan apply # written to /var/log/cloud-init-output.log final_message: "The system is finally up, after $UPTIME seconds"
Note: As of 05 June 2023 we haven’t been able to get a AlmaLinux 9 user-data file working (root password issue and keys don’t work). The format is a lot different than Ubuntu since Ubuntu doesn’t typically use the root user. Watch this space.
meta-data
instance-id: host1.example.com local-hostname: host2.example.com
Generate funny cidata.iso file:
genisoimage -output cidata.iso -V cidata -r -J user-data meta-data
Download the Cloud Image
Make sure you’re in a good working directory as mentioned above. You’ll need to clean up after yourself afterwards.
Ubuntu Focal
wget http://cloud-images.ubuntu.com/focal/current/focal-server-cloudimg-amd64.img
AlmaLinux 9
https://repo.almalinux.org/almalinux/9/cloud/x86_64/images/
https://repo.almalinux.org/almalinux/9/cloud/x86_64/images/AlmaLinux-9-GenericCloud-latest.x86_64.qcow2
Notice Ubuntu supplies .img files and AlmalLinux supplies .qcow2 files. This will be important later.
Convert the Cloud Image to a .raw file
qemu-img convert -f qcow2 -O raw focal-server-cloudimg-amd64.img focal-server-cloudimg-amd64.raw
Generate an new .img file
This will be become your actual VM.
qemu-img create -b focal-server-cloudimg-amd64.img -f qcow2 -F qcow2 hal9000.img 10G
Install the VM
virt-install --name=hal9000 --ram=2048 --vcpus=1 --import --disk path=hal9000.img,format=qcow2 --disk path=cidata.iso,device=cdrom --os-variant=generic --network bridge=virbr0,model=virtio --graphics vnc,listen=0.0.0.0 --noautoconsole
Missing packages?
- yum install genisoimage
- yum install virt-install
Caveats
Caveats with regards to download Cloud Images from different vendors (e.g. Debian track versus Redhat track)
- A caveat is that Cloud Images are sometimes in QCOW2 format, and other times at IMG format.
- AlmaLinux Supplies QCOW2 format
- Ubuntu supplies IMG format
- This is important because later in this process you’ll need to create a conversion, and if you haven’t selected the correct format the steps will break down. This error is easy to see because it will warn you.
- Alternative downloads locations for download of Cloud Images:
- It’s very easy to search for Cloud Image for any vendor.