Automate Multi‑Version OS Deployment with Cobbler

Introduction Operational automation is essential in production environments, especially when managing hundreds or thousands of servers. While PXE can install a single OS version, deploying multiple OS versions requires a more flexible solution; Cobbler provides this capability.

Cobbler Overview Cobbler is a Python‑based tool that wraps PXE to automate OS deployment. It offers CLI and web interfaces, an API for extensibility, and supports physical machines, KVM, Xen, and guest OS installations, as well as integration with configuration management tools like Puppet.

Components The main Cobbler components interact as shown in the diagram below.

Installation

# yum install cobbler -y

Cobbler depends on DHCP, TFTP, rsync, and DNS services. DHCP can be provided by

dhcpd

or

dnsmasq

; TFTP by

tftp‑server

or Cobbler itself; rsync by the

rsync

package; DNS by

bind

or

dnsmasq

. These services are managed independently of Cobbler.

Configure DHCP

# yum install dhcp -y
cp /usr/share/doc/dhcp-4.1.1/dhcpd.conf.sample /etc/dhcp/dhcpd.conf
vim /etc/dhcp/dhcpd.conf
option domain-name "scholar.com";
option domain-name-servers 172.16.0.1;
default-lease-time 43200;
max-lease-time 86400;
log-facility local7;
subnet 172.16.0.0 netmask 255.255.0.0 {
  range 172.16.10.60 172.16.10.70;
  option routers 172.16.0.1;
  next-server 172.16.10.125;
  filename "pxelinux.0";
}
service dhcpd start

Configure rsync and TFTP

# chkconfig tftp on
# chkconfig rsync on
service xinetd start

Configure Cobbler

# service cobblerd start
# service httpd start
cobbler check
# Edit /etc/cobbler/settings
server: 172.16.10.125
next_server: 172.16.10.125
# Install missing loaders
cobbler get-loaders
yum install syslinux -y
cp -r /usr/share/syslinux/* /var/lib/cobbler/loaders/
# Set default password
openssl passwd -1 -salt $(openssl rand -hex 4)
# Update /etc/cobbler/settings with default_password_crypted
service cobblerd restart

Add Distro Mount the installation media and import the OS images.

# mount /dev/cdrom /mnt
# cobbler import --name=CentOS6 --path=/mnt
# cobbler import --name=CentOS7 --path=/mnt

Add Profile Create or modify a kickstart file to point to the correct repository.

url --url=http://172.16.10.125/cobbler/ks_mirror/CentOS-7.0-x86_64

Synchronize Data

# cobbler sync
# For CentOS7, edit /var/lib/tftpboot/pxelinux.cfg/default and add:
inst.repo=http://172.16.10.125/cobbler/ks_mirror/CentOS-7.0-x86_64

Deployment Test Set the target machines to network boot, then install CentOS6 and CentOS7 using the configured Cobbler environment. Screenshots illustrate successful boot and installation processes.

Cobbler Web Interface Install the web UI for easier management.

# yum install cobbler-web -y
# vim /etc/cobbler/modules.conf   # set module = authn_pam
# useradd cobuser
# echo 'cobpass' | passwd --stdin cobuser
# vim /etc/cobbler/users.conf   # add admin = "cobuser"
service cobblerd restart
service httpd restart

Access Test Log in to the Cobbler web console to verify that the configuration and profiles are correctly displayed and can be managed through the UI.