Build Virtual Machine Using KVM/Qemu and Kickstart

Introduction:
We will build a VM using KVM/Qemu hypervisor. This VM build will use a kickstart file. This kickstart file will be served from a web server. Instead of building a full blown web server like apache or nginx, we will build a simple HTTP server using Golang, that will serve our kickstart file.

Environment/Tools used:
Host OS is Debian Jessie (Debian-8). We will build CentOS-7.0 VM on this Debian Host. We will use
CentOS-7-x86_64-Minimal-1511.iso image stored in Host machine to build VM. Make sure Go compiler is installed.

Create Web Server:

mkdir GO_HTTP_SERVER

Create following two files inside GO_HTTP_SERVER directory

$ ls
ks.cfg serve_ks.go

serve_ks.go file:

package main
import (
  "net/http"
)

func main() {
  http.ListenAndServe(":8080", http.FileServer(http.Dir("./")))
}

ks.cfg file

#version=DEVEL
# System authorization information
auth --enableshadow --passalgo=sha512
# Use CDROM installation media
cdrom
# Use text mode install
text
# Run the Setup Agent on first boot
firstboot --disable
# Keyboard layouts
keyboard --vckeymap=uk --xlayouts='uk'
# System language
lang en_GB.UTF-8

# Network information
#network  --bootproto=static --device=eth0 --gateway=192.168.0.1 --ip=192.168.0.61 --nameserver=8.8.8.8 --netmask=255.255.255.0 --ipv6=auto --activate --hostname=centosvm1

# Root password
rootpw --iscrypted $6$pDcoINZetTlq2e2S$Tjz7tBv14Mrw41paKN0O57o.7m7HNWOmIguqdLO6YAA1yrxUcl1mypt5bBKqjVuOqnlNOOoeQH9zJud6FfXcz1
# Do not configure the X Window System
skipx
# System timezone
timezone Europe/London --isUtc
user --name=ocean1 --password=$6$wTphTlXg/5nlzaNK$YoezS.sO80koCnVgyC.kOxF.t3jo0dzk9ey6ENiAPpWme9dfKTFX7ziC.oONjtAh1hDnlLLLq1j4N5YWUlcrK0 --iscrypted
# System bootloader configuration
bootloader --append=" crashkernel=auto console=ttyAMA0,115200 console=tty console=ttyS0" --location=mbr
autopart --type=plain
# Partition clearing information
clearpart --all --initlabel

%packages
@core
kexec-tools

%end

%addon com_redhat_kdump --enable --reserve-mb='auto'

%end

%post --interpreter /usr/bin/python --log=/root/post-log
import os
entirefile=open('/etc/default/grub').read()
entirefile=entirefile.replace('rhgb', '')
entirefile=entirefile.replace('quiet', '')
open('/etc/default/grub', 'w').write(entirefile)
os.system("grub2-mkconfig -o /boot/grub2/grub.cfg")

%end

Note:
1) CentOS-7.0 minimal ISO image does not have perl packages. Therefore I have to use python for post installation task in ks.cfg file.
2) Change your encrypted password.
3) Post installation section in ks.cfg will disable "quiet" boot. That means all boot information will be displayed on console.
4) ks.cfg has kernel boot parameters so that console can be redirected.
5) It uses default network configuration provided by QEMU/KVM. (using default DHCP embedded in qemu).

Run HTTP server

$ cd GO_HTTP_SERVER
$ go run serve_ks.go

verify that webserver is running. Run following command on another terminal.
$ curl http://IPADDRESS_OF_HOSTMACHINE:8080/ks.cfg

You should see output.

Note:
1) Web server is started on port 8080
2) Use machine IP address not localhost or 127.0.0.1 because , VM will communicate with host machine for installation and it cannot communicate with host machine on 127.0.0.1.
3) When you start webserver using "go run serve_ks.go" command, it prints nothing on screen. You can stop web server just by pressing Ctrl-c.

Build VM
Create Storage File

# qemu-img create -f qcow2 centos-7.qcow2 5G

Start VM in user networking mode

# qemu-system-x86_64 -enable-kvm -cpu host -m 1024 -cdrom /home/testuser/Downloads/CentOS-7-x86_64-Minimal-1511.iso -hda /home/testuser/Downloads/KVM_IMAGES/centos-7.qcow2  -boot d

A new window will pop up with boot options. Press TAB. Some options will be visible. Append following to those options.

ks=http://IPADDRESS_OF_HOSTMACHINE:8080/ks.cfg

Once system installation is complete, run VM using following command.
Please note the omission of "-boot d".

# screen -S centos qemu-system-x86_64 -enable-kvm -cpu host -m 1024 -cdrom /home/testuser/Downloads/CentOS-7-x86_64-Minimal-1511.iso -hda /home/testuser/Downloads/KVM_IMAGES/centos-7.qcow2

Update kernel boot parameters so that console can be redirected to terminal where qemu command is fired. then run following command. (note -nographic) (attached ks.cfg has this functionality). So you do not need to manually update kernel boot parameters.

# screen -S centos qemu-system-x86_64 -enable-kvm -cpu host -m 1024 -cdrom /home/testuser/Downloads/CentOS-7-x86_64-Minimal-1511.iso -hda /home/testuser/Downloads/KVM_IMAGES/centos-7.qcow2  -nographic

Note: Please note that We started VM in a screen session so that VM console can be attached or detached easily.
We do not need to do this when VMs are build using libvirtd. libvirtd provides many functionalities .