Cloud Instance with Cloud-Init on KVM

I wanted to run an Ubuntu server cloud instance locally on KVM hypervisor. I also wanted to run cloud-init on the local setup in order to experiment a bit with it. So that means, downloading a UEC image, booting it under KVM, and passing cloud-init parameters to it as it boots. Much to my surprise things were far easier than I expected, all thanks to our rocking Ubuntu cloud team. Here's the script I cobbled together, most of it is basically a rip off from this UEC Images wiki page.

So what this does is, it:

• Downloads a UEC image of natty server daily i386 if it doesn't exist
• Sets a few variables
• Creates a qcow disk image, shadowing/cowing/differencing the downloaded image. This is to keep the originally downloaded image pristine
• Downloads some sample user-data and meta-data (warning, this runs arbitrary commands and injects keys inside your VM, only use for testing!). To experiment with cloud-init you'd have to modify the user-data to your liking
• Runs a local simple webserver (port 8000)
• Boots the cow image in a local kvm. As it boots, you'll notice on your terminal the following two requests being made "GET /meta-data" and "GET /user-data". Cloud-init uses this data to customize the image as it boots
• Once you close kvm, kills the web-server

So all you need to do, is create an empty directory, put this script in it and run it

uecnattyservercurrent=http://uec-images.ubuntu.com/server/natty/current/natty-server-uec-i386.tar.gz
tarball=$(basename $uecnattyservercurrent)
[ -f ${tarball} ] || wget ${uecnattyservercurrent}
contents=${tarball}.contents
tar -Sxvzf ${tarball} | tee "${contents}"
cat natty-server-uec-i386.tar.gz.contents
base=$(sed -n 's/.img$//p' "${contents}")
kernel=$(echo ${base}-vmlinuz-*)
floppy=${base}-floppy
img=${base}.img
qemu-img create -f qcow2 -b ${img} disk.img
wget http://smoser.brickies.net/ubuntu/uec-seed/meta-data
wget http://smoser.brickies.net/ubuntu/uec-seed/user-data
python -m SimpleHTTPServer &
websrvpid=$!
kvm -drive file=disk.img,if=virtio,boot=on -kernel "${kernel}" -append "ro init=/usr/lib/cloud-init/uncloud-init root=/dev/vda ds=nocloud-net;s=http://192.168.122.1:8000/ ubuntu-pass=ubuntu"
kill $websrvpid