cloud-config.cfg

#cloud-config
phone_home:
  url: "http://tinkerbell.ewr1.packet.net/phone-home"
  post:
    - instance_id
  tries: 5
autoinstall:
  version: 1
  # use interactive-sections to avoid an automatic reboot
  #interactive-sections:
  #  - locale
  apt:
    # even set to no/false, geoip lookup still happens
    #geoip: no
    preserve_sources_list: false
    primary:
    - arches: [amd64, i386]
      uri: http://us.archive.ubuntu.com/ubuntu
    - arches: [default]
      uri: http://ports.ubuntu.com/ubuntu-ports
  # r00tme
  identity:
    hostname: focal-autoinstall
    password: $6$.c38i4RIqZeF4RtR$hRu2RFep/.6DziHLnRqGOEImb15JT2i.K/F9ojBkK/79zqY30Ll2/xx6QClQfdelLe.ZjpeVYfE8xBBcyLspa/
    username: ubuntu
  keyboard: {layout: us, variant: ''}
  locale: en_US.UTF-8
  network:
    network:
      version: 2
      renderer: networkd
      ethernets:
        switchports:
          match:
            name: en*
          #mtu: 1280
          dhcp4: no
      bonds:
        bond0:
          interfaces:
          - switchports
          parameters:
            mode: 802.3ad
            mii-monitor-interval: 100
            down-delay: 200
            up-delay: 200
            transmit-hash-policy: layer3+4
            lacp-rate: fast
          critical: true
          dhcp4: yes
      # vlans:
      #   bond0.${VLAN_ID_1}:
      #     addresses: [169.254.254.${LAST_DIGIT}/24]
      #     id: ${VLAN_ID_1}
      #     link: bond0
      #   bond0.${VLAN_ID_0}:
      #     link-local: [ ipv4, ipv6 ]
      #     addresses: [192.168.100.${LAST_DIGIT}/24]
      #     id: ${VLAN_ID_0}
      #     link: bond0
      #     routes:
      #     - to: 0.0.0.0/0
      #       via: 192.168.100.1
  ssh:
    #allow-pw: true
    #authorized-keys: []
    install-server: true
  # this creates an bios_grub partition, /boot partition, and root(/) lvm volume
  storage:
    config:
    - {ptable: gpt, path: /dev/sda, wipe: superblock, preserve: false, name: '', grub_device: true,
      type: disk, id: disk-sda}
    - {device: disk-sda, size: 1048576, flag: bios_grub, number: 1, preserve: false,
      type: partition, id: partition-0}
    - {device: disk-sda, size: 1073741824, wipe: superblock, flag: '', number: 2,
      preserve: false, type: partition, id: partition-1}
    - {fstype: ext4, volume: partition-1, preserve: false, type: format, id: format-0}
    - {device: disk-sda, size: -1, wipe: superblock, flag: '', number: 3,
      preserve: false, type: partition, id: partition-2}
    - name: ubuntu-vg
      devices: [partition-2]
      preserve: false
      type: lvm_volgroup
      id: lvm_volgroup-0
    - {name: ubuntu-lv, volgroup: lvm_volgroup-0, size: 100%, preserve: false,
      type: lvm_partition, id: lvm_partition-0}
    - {fstype: ext4, volume: lvm_partition-0, preserve: false, type: format, id: format-1}
    - {device: format-1, path: /, type: mount, id: mount-1}
    - {device: format-0, path: /boot, type: mount, id: mount-0}
write_files:
  # override the kernel package. Why?
  - path: /run/kernel-meta-package
    content: |
      linux-generic
    owner: root:root
    permissions: "0644"
  # attempt to also use an answers file by providing a file at the default path.  It did not seem to have any effect
  #- path: /subiquity_config/answers.yaml
  #  content: |
  #    InstallProgress:
  #      reboot: no
  #  owner: root:root
  #  permissions: "0644"
runcmd:
- echo Marty > /root/it-worked

run.sh

#!/usr/bin/env bash
METAL_PLAN=${METAL_PLAN:-t1.small.x86}
#GIST_URL="https://gist.githubusercontent.com/displague/11b6fc926d8d697e28c7a5cbe17d16ff/raw/f11c247e87290cb1248a2223588daf5cfd3ab1b3/ubuntu.ipxe"
END="$(TZ=UTC date -v+2H +"%Y-%m-%dT%H:%M:%SZ")"
CC=$(cat cloud-config.cfg | python3 -c "import urllib.parse, sys; print(urllib.parse.quote_plus(sys.stdin.read()))")
IPXE=$(cat ubuntu.ipxe | envsubst '${CC}')
echo -e "#!ipxe\n$IPXE\n" > ipxe.tmp

metal device create \
	--userdata-file cloud-config.cfg \
	--plan $METAL_PLAN \
	--hostname "ipxe-test" \
	--tags "ipxe,testing,ubuntu" \
	--operating-system custom_ipxe \
	--facility ewr1 \
	--userdata-file ipxe.tmp \
	--termination-time "$END"

# --ipxe-script-url "$GIST_URL" \

ubuntu.ipxe

#!ipxe
dhcp net0

set base-url http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/ubuntu-installer/amd64/
kernel ${base-url}/linux console=ttyS1,115200n8 ci.ds=ec2;metadata_urls=https://metadata.platformequinix.com/metadata,http://metadata.packet.net/ cc: ${CC} end_cc
initrd ${base-url}/initrd.gz
boot

ci.ds=ec2;metadata_urls=https://metadata.platformequinix.com/metadata,http://metadata.packet.net/ ? (comma for multiple?)

nocloud and nocloud-net explain ; use: https://cloudinit.readthedocs.io/en/latest/topics/datasources/nocloud.html
ec2 has metadata_urls: https://cloudinit.readthedocs.io/en/latest/topics/datasources/ec2.html#configuration

via @thebsdbox

This limit depends on the architecture and is between 256 and 4096 characters. 
It is defined in the file ./include/asm/setup.h as COMMAND_LINE_SIZE.

the URL encoded cc: block will need to be kept small.

The current length may explain the black screen I received when attempting to boot this.

Hook is set to 2048, so tons of room for gzip/base64!