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Rackdog supports iPXE chainloading so you can control how a server boots. Instead of using a stock OS install, point Rackdog at your own iPXE script and take over the boot and provisioning process. To use it, select the Custom iPXE OS option when ordering a server and provide your iPXE URL.

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How it works

When you provide an iPXE URL, Rackdog wraps it in a chainloading script that runs at boot: 
#!ipxe
dhcp || echo "dhcp failed (continuing)"

echo Booting user chain: <your-url>
chain --autofree <your-url> || goto chain_failed

:chain_failed
echo Chain failed. Dropping to shell...
shell
Your URL is substituted into this template at provision time.

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What you provide

Supply a publicly reachable URL that returns a valid iPXE script, for example: 
https://example.com/boot.ipxe
Some flows also accept an inline script body in place of a URL.

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Example script

A minimal script that boots a Linux kernel: 
#!ipxe
kernel https://boot.example.com/vmlinuz initrd=initrd.img
initrd https://boot.example.com/initrd.img
boot

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When to use it

Reach for iPXE when you need a custom OS image, a preconfigured environment, integration with your own provisioning system, ephemeral or stateless workloads, or just direct control over the boot process. For standard images and faster setup, stick with normal provisioning.

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Requirements

  • The iPXE URL must be reachable from the Rackdog network.
  • The script must be valid iPXE syntax.
  • Every asset referenced by the script (kernel, initrd, and so on) must be reachable from the server at boot.

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What happens on failure

If chainloading fails, the server prints the error and drops into the iPXE shell. From there you can debug interactively: 
ifstat                              # check network state
dhcp                                # retry DHCP
chain https://example.com/boot.ipxe # try a chain by hand

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Good habits

  • Host your scripts on infrastructure you trust to be available when servers boot.
  • Keep scripts short and deterministic so boots are predictable.
  • Version or log your boot scripts so you can trace what a server ran.
  • Validate a script locally before pointing production servers at it.