The data source ``NoCloud`` and ``NoCloudNet`` allow the user to provide user-data
and meta-data to the instance without running a network service (or even without
having a network at all).

You can provide meta-data and user-data to a local vm boot via files on a `vfat`_
or `iso9660`_ filesystem. The filesystem volume label must be ``cidata``.

These user-data and meta-data files are expected to be
in the following format.

::

  /user-data
  /meta-data

Basically, user-data is simply user-data and meta-data is a yaml formatted file
representing what you'd find in the EC2 metadata service.

Given a disk ubuntu 12.04 cloud image in 'disk.img', you can create a sufficient disk
by following the example below.

::
    
    ## create user-data and meta-data files that will be used
    ## to modify image on first boot
    $ { echo instance-id: iid-local01; echo local-hostname: cloudimg; } > meta-data
    
    $ printf "#cloud-config\npassword: passw0rd\nchpasswd: { expire: False }\nssh_pwauth: True\n" > user-data
    
    ## create a disk to attach with some user-data and meta-data
    $ genisoimage  -output seed.iso -volid cidata -joliet -rock user-data meta-data
    
    ## alternatively, create a vfat filesystem with same files
    ## $ truncate --size 2M seed.img
    ## $ mkfs.vfat -n cidata seed.img
    ## $ mcopy -oi seed.img user-data meta-data ::
    
    ## create a new qcow image to boot, backed by your original image
    $ qemu-img create -f qcow2 -b disk.img boot-disk.img
    
    ## boot the image and login as 'ubuntu' with password 'passw0rd'
    ## note, passw0rd was set as password through the user-data above,
    ## there is no password set on these images.
    $ kvm -m 256 \
       -net nic -net user,hostfwd=tcp::2222-:22 \
       -drive file=boot-disk.img,if=virtio \
       -drive file=seed.iso,if=virtio

**Note:** that the instance-id provided (``iid-local01`` above) is what is used to
determine if this is "first boot".  So if you are making updates to user-data
you will also have to change that, or start the disk fresh.

Also, you can inject an ``/etc/network/interfaces`` file by providing the content
for that file in the ``network-interfaces`` field of metadata.  

Example metadata:

::
    
    instance-id: iid-abcdefg
    network-interfaces: |
      iface eth0 inet static
      address 192.168.1.10
      network 192.168.1.0
      netmask 255.255.255.0
      broadcast 192.168.1.255
      gateway 192.168.1.254
    hostname: myhost

.. _iso9660: https://en.wikipedia.org/wiki/ISO_9660
.. _vfat: https://en.wikipedia.org/wiki/File_Allocation_Table
