docker-cobbler

Dockerfile will build an image with latest cobbler from source code, atftp server isc dhcpd server and apache2 all managed by supervisord.

docker build ./cobbler -t shadwell/docker-cobbler-supervisord:#.#.# --build-arg GIT_COMMIT=$(git log -1 --format=%h)

commit used to build the docker image can be retrieved using:

docker inspect <docker_image_id> | jq '.[].ContainerConfig.Labels'

Configure dhcp-helper

Cobbler container runs in unprivileged mode, to be able to deliver dhcp broadcast to dhcp server in container we use dhcp-helper which will relay messages to either network device or dhcp server ip.

• If you are using docker run

$ sudo vi /etc/default/dhcp-helper
DHCPHELPER_OPTS="-b docker0 -i ens3"

• when usign docker-compose

$ sudo vi /etc/default/dhcp-helper
DHCPHELPER_OPTS="-i ens3 -s 172.16.238.10"

• start dhcp-helper

$ sudo systemctl  start dhcp-helper.service

Download Ubuntu ISO

• http://cdimage.ubuntu.com/releases/
• http://releases.ubuntu.com

Download and mount loop

Below script will download Bionic and Xenial iso.

$ ./download-iso-and-mount.sh

Docker run cobbler image

$ docker run -dt  -v /mnt/:/mnt -p 80:80/tcp -p 69:69/udp  --name cobbler urosorozel/cobbler:latest

Docker-compose

$ docker-compose up --build -d

Import Xenial and Bionic

Run script against container

docker exec -it cobbler /bin/bash -c "$(<import-iso.sh)"

Test Docker Cobbler in a VM

Load tftp iptables modules

$ sudo modprobe ip_conntrack_tftp ip_nat_tftp
$ sudo iptables -t raw -A PREROUTING -p udp --dport 69 -j CT --helper tftp

Install packages

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
$ sudo apt-get update
$ sudo apt-get install docker-ce qemu-kvm virtinst libvirt-bin python3-pip

Update group membership for Docker and Libvirt

For Xenial

$ sudo usermod -aG docker,libvirtd ubuntu

or Bionic

$ sudo usermod -aG docker,libvirt ubuntu

logout and login to take an affect

$  sudo su - $USER

Add libvirt network

• update subnet details if required

$ echo "<network>
        <name>cobbler</name>
        <dns enable="no"/>
        <forward mode='nat'/>
        <bridge name='cobbler' stp='on' delay='0'/>
        <ip address='192.168.10.1' netmask='255.255.255.0'></ip>
        </network>" | virsh net-define /dev/stdin

• start cobbler libvirt network

$ sudo virsh start cobbler

Update DHCP helper (DHCP relay)

• When testing in VM we want to relay all DHCP requests from cobbler bridge to container subnet

$ sudo vi /etc/default/dhcp-helper
DHCPHELPER_OPTS="-i cobbler -s 172.16.238.10"

• start dhcp-helper

$ sudo systemctl  restart dhcp-helper.service

Install Docker-compose

$ sudo curl -L "https://github.com/docker/compose/releases/download/1.24.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
$ sudo chmod +x /usr/local/bin/docker-compose

Clone repository

$ git clone https://github.com/urosorozel/docker-cobbler.git

Update docker-compose variables

• Update variable according to you environment

# Cobbler server IP/hostname
COBBLER_SERVER_HOST_IP=192.168.122.91
# TFTP server
COBBLER_NEXT_SERVER_HOST_IP=192.168.122.91

# SSH public key
COBBLER_PUBLIC_SSH_KEY=

# Dhcp settings
COBBLER_SUBNET=192.168.10.0
COBBLER_NETMASK=255.255.255.0
COBBLER_ROUTERS=192.168.10.1
COBBLER_NAMESERVERS=8.8.8.8,1.1.1.1
COBBLER_DHCP_RANGE=192.168.10.50 192.168.10.100

# Proxy
COBBLER_PROXY_URL_EXT=
COBBLER_PROXY_URL_INT=

Run Cobbler

$ docker-compose up --build -d

Download and mount loop

Below script will download Bionic and Xenial iso.

$ ./download-iso-and-mount.sh

Import Xenial and Bionic

Run script against container

docker exec -it cobbler /bin/bash -c "$(<import-iso.sh)"

Start qemu virtual machine

$ virt-install --connect qemu:///system \
               --name demo \
               --vcpu 2 \
               --memory 2048 \
               --disk size=10 \
               --pxe \
               --network network=cobbler,mac=0c:c4:7a:bb:ff:f1 \
               --virt-type qemu \
               --console pty,target_type=serial \
               --graphics vnc,listen=0.0.0.0 \
               --os-variant ubuntu18.04