Automate RHEL 9 and CentOS Stream 9 Installation on KVM Using Kickstart

In Infrastructure as Code, Job Automation, Linux Basics, Shell Scripting, System Administration, Virtualization, Web Servers
July 23, 2025
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Automating Linux installations in virtual environments saves time and ensures all your systems are built consistently. Kickstart is Red Hat’s proven technology for unattended installations. This guide shows how to use Kickstart for RHEL 9 and CentOS Stream 9 VM deployment on a KVM (Kernel-based Virtual Machine) hypervisor, using practical, hands-on steps.

1. Prerequisites

KVM & libvirt installed on your Linux host (with qemu-kvm, libvirt, and virt-install packages).
RHEL 9 or CentOS Stream 9 ISO available locally.
Root or sudo privileges for virtualization commands.
Kickstart configuration file ready for use (explained below).
Basic networking (using libvirt’s virbr0 NAT or a bridged setup).

2. Understanding Kickstart

Kickstart is a plain-text file containing answers for every installer prompt: language, disk layout, users, packages, network, and more. By supplying a Kickstart file, you allow RHEL or CentOS to install without any human interaction.

Kickstart is highly customizable, supporting advanced configuration and scripting, making it popular for data center automation and DevOps workflows.

3. Creating a Kickstart File

Start by creating a ks.cfg file on your KVM host. Use your favorite text editor, e.g.:

vim ~/ks.cfg

Sections of a Kickstart file:

Installation source & mode: Use cdrom and text for headless automation.
Localization: Set language, keyboard, timezone.
License: For RHEL, use eula --agreed.
Network: Define network interface (DHCP/static), hostname.
Disk partitioning: Use autopart for auto-LVM, or detailed manual partitioning.
Users: Set encrypted root password, create an admin user.
Security: Set SELinux/firewall options.
Packages: Specify base packages/groups.
Optional scripts: %pre and %post for customization.

Example:

text
cdrom
lang en_US.UTF-8
keyboard --vckeymap=us
eula --agreed
firstboot --disable
reboot

network --bootproto=dhcp --device=eth0 --ipv6=off --activate
network --hostname=example-vm.local
selinux --enforcing
firewall --enabled --ssh

bootloader --location=mbr --boot-drive=vda --append="net.ifnames=0 biosdevname=0"
clearpart --all --initlabel
autopart --type=lvm

rootpw --iscrypted $6$YOURHASH
user --name=devops --groups=wheel --password=$6$USERHASH --iscrypted --gecos="DevOps User"
timezone UTC --utc

%packages
@^minimal-environment
@core
openssh-server
vim
bash-completion
%end

Generate password hashes with: openssl passwd -6 "YourPassword".

4. Hosting the Kickstart File

The VM needs network access to fetch the Kickstart. The simplest way is to serve ks.cfg via HTTP using Python:

cd ~
python3 -m http.server 8000

From your VM, the host can usually be reached as 192.168.122.1 (with libvirt default NAT).

Test access locally:

curl http://192.168.122.1:8000/ks.cfg

5. Running Automated Install with virt-install

Use the virt-install tool to create a VM and pass the Kickstart URL as a boot argument.

Sample command:

sudo virt-install \
  --name centos9-auto \
  --ram 2048 \
  --vcpus 2 \
  --disk size=20 \
  --os-variant centos-stream9 \
  --network network=default \
  --location /var/lib/libvirt/images/CentOS-Stream-9-latest-x86_64-dvd1.iso \
  --graphics none \
  --console pty,target_type=serial \
  --extra-args "inst.ks=http://192.168.122.1:8000/ks.cfg console=ttyS0,115200n8"

Starting install...
Retrieving file vmlinuz...                                      |  10 MB  00:00:01
Retrieving file initrd.img...                                   |  72 MB  00:00:03
Allocating 'centos9-auto.qcow2'                                 |  20 GB  00:00:01

Connected to domain 'centos9-auto'
Escape character is ^] (Ctrl + ])

[    0.000000] Linux version 5.14.0-366.el9.x86_64 ([email protected]) (gcc (GCC) 11.3.1 20220421 (Red Hat 11.3.1-2), GNU ld version 2.35.2-24.el9) #1 SMP Thu Aug 10 14:04:00 UTC 2023
[    0.000000] Command line: BOOT_IMAGE=(hd0,msdos1)/images/pxeboot/vmlinuz inst.stage2=hd:LABEL=CentOS-Stream-9-x86_64-dvd inst.ks=http://192.168.122.1:8000/ks.cfg console=ttyS0,115200n8
...
[    1.946908] dracut: dracut-057-13.git20230510.el9
[    2.020312] systemd[1]: Detected architecture x86-64.

CentOS Stream 9 installer booting

Starting language support...
Starting network...
Starting installation process...
...
[  OK  ] Started Network Manager Script Dispatcher Service.
[  OK  ] Reached target Network.
[  OK  ] Started Network Manager Wait Online.
...
anaconda 23.10.1-2.el9 starting
...
 * Setting language to en_US.UTF-8
 * Setting keyboard layout to us
 * Setting time zone to UTC
 * Enabling SELinux (enforcing)
 * Enabling firewall and allowing SSH

 * Starting automated installation with Kickstart: http://192.168.122.1:8000/ks.cfg
 * Using CDROM as installation source
 * Configuring network interface eth0 (DHCP)
 * Setting hostname to example-vm.local

 * Partitioning disk /dev/vda
   - Removing all partitions
   - Creating LVM volumes
   - Formatting /boot and /
   - Setting up swap

 * Creating user account 'devops'
 * Setting root password

 * Installing packages: @^minimal-environment, @core, openssh-server, vim, bash-completion
...
Installing : glibc-2.34-50.el9.x86_64                                1/100
Installing : systemd-249-37.el9.x86_64                               2/100
...
Installing : openssh-server-8.7p1-36.el9.x86_64                     70/100
...
Post-installation setup tasks:
 * Enabling chronyd service
 * Writing bootloader configuration
 * Finalizing SELinux context labels
...
Complete!
 * Installation complete. Rebooting system.
[  OK  ] Reached target Reboot.
[  240.342112] systemd-shutdown[1]: Syncing filesystems and block devices.
[  241.187761] Restarting system.

Connection to domain 'centos9-auto' closed by the guest.

Adjust --os-variant and ISO path as needed.
--extra-args passes the Kickstart URL and directs output to serial console.
The install will run non-interactively and reboot when done.

6. Post-Installation

Use virsh list --all to see your VM.
Access the console with virsh console <vm-name>.
Log in with the admin user or root password you set in Kickstart.

You can now SSH into the VM, update packages, or further configure it as needed.

7. Troubleshooting

Kickstart not found: Confirm Python HTTP server is running; verify the correct IP and port.
Syntax errors: Validate your Kickstart with ksvalidator.
Network issues: Ensure --activate is set for the network in Kickstart and check your VM’s NIC config after install.
Installer prompts: If installation isn’t fully automated, re-check required directives (e.g., password, eula).
Logs: Check Anaconda logs in the VM’s /tmp directory during install for errors.

8. Advanced Topics

Custom partitions: Use part/logvol directives.
Static IP: Change --bootproto=static and set IP, gateway, nameserver.
Automate at scale: Integrate with Cobbler, Foreman, or Ansible for mass deployment.
Pre/Post scripts: Add scripts to %pre or %post sections for custom automation.
Security: Store Kickstart files securely; use encrypted passwords, avoid plaintext secrets.

9. Conclusion

Kickstart allows you to deploy RHEL 9 and CentOS Stream 9 VMs on KVM rapidly and consistently. By automating the OS installation, you reduce manual work, minimize configuration drift, and prepare your infrastructure for rapid scaling and CI/CD. The process is extensible for more complex production requirements—feel free to customize the Kickstart file for your exact needs.