Comment 0 for bug 1688606

=== Begin SRU Template ===
[Impact]
MAAS has an interest in booting entirely ephemerally without iscsi root.
The package cloud-initramfs-rooturl supports booting with root coming
from a url.
  root=http://..../squashfs

This function will be used to pxe boot into a RAM only system with no
dependency on the network.

[Test Case]
1. make sure squashfs module is in the initramfs
   squashfs module is not automatically added to initramfs in precise.
   Just ensure that it is there.

   $ echo "manual_add_modules squashfs" |
      sudo tee /etc/initramfs-tools/hooks/squashfs

2. install cloud-initramfs-rooturl
   sudo apt-get update
   sudo apt-get install cloud-initramfs-rooturl

3. collect the kernel and newly generated initramfs

   sudo cat /boot/vmlinu?-$(uname -r) > kernel
   cp /boot/initrd.img-$(uname -r) initrd

4. Download a squashfs image or a .tar.xz image

   rel="xenial"
   burl="http://cloud-images.ubuntu.com/daily/server"
   file="$rel-server-cloudimg-amd64-root.tar.xz"
   file="$rel-server-cloudimg-amd64.squashfs"
   wget "$burl/$rel/current/$file" -O "$file"

5. run a web server
   python -m SimpleHTTPServer 9999 &

6. create a seed disk for cloud-init.

   $ cat > my-user-data <<EOF
   #cloud-config
   password: passw0rd
   chpasswd: { expire: False }
   ssh_pwauth: True

   $ echo "instance-id: $(uuidgen || echo i-abcdefg)" > my-meta-data
   $ cloud-localds seed.img my-user-data my-meta-data

7. Boot a vm using the kernel, initrd and url.

   cmdline="root=http://10.0.2.2:9999/$file console=ttyS0 -v "
   cmdline="${cmdline} overlayroot=tmpfs"

   qemu-system-x86_64 -enable-kvm
      -device virtio-net-pci,netdev=net00 \
      -netdev type=user,id=net00 \
      -drive if=virtio,file=seed.img \
      -m 1G -nographic \
      -kernel kernel -initrd initrd \
      -append "root=$cmdline"

[Regression Potential]
Low. This is adding a package previously not present.

[Other Info]

=== End SRU Template ===