https://github.com/rgolangh/assisted-bootloader

assisted-bootloader
https://github.com/rgolangh/assisted-bootloader

Last synced: 29 days ago
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assisted-bootloader

• Host: GitHub
• URL: https://github.com/rgolangh/assisted-bootloader
• Owner: rgolangh
• Created: 2022-10-24T09:02:53.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2023-02-20T13:45:45.000Z (almost 2 years ago)
• Last Synced: 2024-11-07T10:53:18.396Z (3 months ago)
• Language: Shell
• Size: 124 MB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.adoc

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README

        
Assisted Bootloader

-------------------

// URLS:

:assisted-bootloader: https://github.com/rgolangh/u-root/blob/c18bcfb89aab71a6bbaa94d05b7cc85501a24306/cmds/assisted-bootloader/assisted-bootloader.go

To keep lowering the bar for installing a cluster,the assisted installer supplied a custom ISO to boot

a machine with the target cluster relevant bits in its ignition and rootfs.

The opportunity to cut this even further is to make a more generic booting tool that can be pointed at any

cluster endpoint (the InfraEnv object) and pull the boot artifacts directly from it. 

As more cloud providers looking for a way to add nodes using their infra, every one with its set of features

and limitation (like no boot from ISO, or limited or non-direct user-data support), a search for more 

decoupled and streamlined way to add any machine to a cluster is important.

This effort has 2 main artifacts:

* an {assisted-bootloader}[init program] that runs after the kernel boots(built using u-root) and

* a raw, bootable, ~60M disk image.

Bootloading sequence

--

* boot a node with a disk created from that image (large enough for a full worker install)

* assisted-bootloader programs starts with infra-env-id and token arguments

* parses the iPXE script of the infra-env

* downloads kernel, initrd, and cmdline from infra-env

* `kexec` into the kernel and initrd (of the assisted ISO)

* normal assisted flow with the agent takes place

To create a complete initramfs using the u-root fork:

[source, bash]

make initrd

To produce the disk image:

[source, bash]

make disk-image

To use the image locally, for exploration and dev:

[source, bash]

make run-vm

Demo of the disk in action with a Linode instance:

image::assisted-bootloader-with-linode.gif[]