Dockerized PXE

A Docker image serving as a standalone PXE (running dnsmasq). This server can be placed in an existing network infrastructure with an already configured DHCP server or in a network without any DHCP server.

This PXE currently serves:

• MemTest86+

Dependencies

These are the dependencies required to build and run the container image:

• Docker 1.12+

How to run

The ENTRYPOINT of this image is set to run dnsmasq in no-daemon mode.

You can add one or more desired dhcp-ranges as command-line options. For more information about dnsmasq command-line options, refer to dnsmasq documentation.

The easiest way to run containers based off this container image without configuring DHCP relays in your network, is to run a such containers using the network of the host running them. If you're using Docker, you can add the --net=host option when running the container:

docker run -it --rm --net=host ferrarimarco/pxe

The container image is also available on GitHub container registry: ghcr.io/ferrarimarco/pxe.

This container image is multi-platform, and supports the following platforms:

• linux/amd64
• linux/arm64

Integrated DHCP server

If you want to enable the integrated DHCP server for a given IP address range add a dhcp-range option: dhcp-range=x.x.x.x,y.y.y.y,z.z.z.z where x.x.x.x is the start of the range, y.y.y.y is the end and z.z.z.z is the subnet mask.

Standalone DHCP server

If you want to use an existing DHCP server and let dnsmasq handle only the PXE, add a dhcp-range option: dhcp-range=x.x.x.x,proxy where x.x.x.x is the IP address of the server running dnsmasq.

How to modify the configuration

All the configuration files can be modified at will. Look at the Dockerfile to see where they are (mainly in /etc and /var/lib/tftpboot) and overwrite them with your own (mounting volumes from the Docker host or rebuilding the image).

Additional PXE Boot Menu Entries

If you just want to add additional menu entries to the boot menu, overwrite the contents of /var/lib/tftpboot/pxelinux.cfg/additional_menu_entries file. The syntax for this file is described in the syslinux documentation.

Example: 2nd Memtest86+ plus Ubuntu 16.04 Boot Options

Here is an additional_menu_entries file to include (along with the default Memtest86+) two additional boot options: a customized Memtest86+ and Ubuntu 16.04.

LABEL memtest86-2
  MENU LABEL Memtest86+ 2nd entry
  KERNEL /memtest/memtest86+
LABEL ubuntu-16-04-amd64
  MENU LABEL Ubuntu 16.04 amd64
  KERNEL /ubuntu/16.04/16.04.2-server-amd64/install/netboot/ubuntu-installer/amd64/linux
  APPEND /install/vmlinuz auto=true interface=eth0 hostname=cluster domain=home url=tftp://<pxe-container-ip>/preseed/16.04/preseed.cfg initrd=ubuntu/16.04/16.04.2-server-amd64/install/netboot/ubuntu-installer/amd64/initrd.gz debian-installer=en_US locale=en_US kbd-chooser/method=us keyboard-configuration/modelcode=SKIP keyboard-configuration/layout=USA keyboard-configuration/variant=USA console-setup/ask_detect=false --

Testing and validating the setup

Test dependencies

1. Virtualbox 5.1.16+
2. Vagrant 1.9.3+

How to run the test environment

1. Check the IP address ranged configured by the Virtualbox DHCP server and configure your dhcp-range and /var/lib/tftpboot/pxelinux.cfg/default accordingly.
2. Run the container with a suitable DHCP configuration and the --net=host option.
3. Run vagrant up from the root of the directory where you cloned this repository. A Virtualbox VM (with a NATed network adapter) will boot from the given PXE.

Example

Virtualbox runs a DHCP server by default in each virtual network. If you want to test the PXE feature you have to run a container based on this image with dnsmasq as a DHCP proxy (see Standalone Mode) and with the host network stack (see the --net=host option) so you know in advance the IP address of the container running dnsmasq: it's the same as the Docker host!

For example, if Virtualbox DHCP server assigns addresses in the 192.168.56.0/24 subnet (check the virtual network configuration of the host-only network assigned to a VM to gather this information), then the dhcp-range option to enable a DHCP proxy could be: dhcp-range=192.168.56.2,proxy, where 192.168.56.2 is the address assigned to the Docker host running the container based on this image in "host network" mode.

Remember to also update any IP address in /var/lib/tftpboot/pxelinux.cfg/default you may have configured, if you serve any content from the TFTP server (like a preseed.cfg for example) to point to the IP address of the container running this PXE. For this reason, it could be useful to manually assign (or reserve) IP addresses (or better, hostnames!) for containers running this PXE.