Boot Ubuntu maas kernel and initrd with cloud-init network seed.

README.md

Boot Ubuntu MAAS kernel, initrd and squashfs with cloud-init seed data.

The demo-it script here will do the following:

• download kernel and initrd from published MAAS images
• download the minimal squashfs image from cloud-images.ubuntu.com.
  We use the minimal image just because it is smaller than the maas provided ephemeral image. We could use that just as well.
• create cloud-init 'user-data' and 'meta-data'
• boot qemu with the provided kernel and initrd use the kernel command line to:
  • provide it with a 'rooturl` to the squashfs image
  • use overlayfs to give writable space
  • provide cloud-init with a 'nocloud-net' datasource

Once you run, you can log in with 'ubuntu' and 'passw0rd'.

Notes

• The code as it is has a hard coded 'baseurl'. Better would be to use query the simplestream data at http://images.maas.io/ephemeral-v3/stable/streams/v1/ to get the latest versions.

demo-it

#!/bin/sh

myurl="http://10.0.2.2:8888"
baseurl="http://images.maas.io/ephemeral-v3/stable/focal/amd64/20220131.1"
kurl="$baseurl/hwe-20.04/generic/boot-kernel"
iurl="$baseurl/hwe-20.04/generic/boot-initrd"
surl="$baseurl/squashfs"
surl="https://cloud-images.ubuntu.com/minimal/daily/focal/20220210/focal-minimal-cloudimg-amd64.squashfs"

dl() { 
    [ -f "$2" ] && return 0
    wget "$1" -O "$2.tmp" && mv "$2.tmp" "$2"
}

fail() { echo "$@" 1>&2; exit 1; }

dl "$kurl" boot-kernel &&
    dl "$iurl" boot-initrd &&
    dl "$surl" squashfs ||
    fail "failed downloads"

if [ ! -e "user-data" ]; then
    cat > "user-data" <<EOF
#cloud-config
password: passw0rd
chpasswd: { expire: False }
ssh_pwauth: True
EOF
fi

if [ ! -e "meta-data" ]; then
   echo "instance-id: i-demo" > meta-data
fi

append="root=$myurl/squashfs console=ttyS0 overlayroot=tmpfs"
append="$append ds=nocloud-net;seedfrom=$myurl/"
qemu-system-x86_64 \
    -enable-kvm \
    -device virtio-net-pci,netdev=net00 \
    -netdev type=user,id=net00 \
    -m 1G -nographic \
    -kernel boot-kernel -initrd boot-initrd \
    -append "$append break=bottom,init"