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[Pádraig Brady <P@xxxxxxxxxxxxxx>]

On 06/01/2012 10:55 AM, William Herry wrote:
> I have been spend all days to search metadata and file injection related info with Google,
> there are few doc or blog about this topic (or I am not use the proper keyword)
> I know about this is only pieces
> 
> what I know now is:
> cloud-init can inject files to instance and a lot other things, seems only on ubuntu, 

cloud-init is available for Fedora now.
There is also a test package available for RHEL and derivatives:
http://pbrady.fedorapeople.org/cloud-init-el6/

> I can inject ssh key with qemu-nbd

If you can do that, you can also inject 'metadata',
'files' and root 'passwords'. Note only failure to
inject 'files' will result in a failure to boot the guest.

> my question is:
> what is in metadata, how can I use matadata
> there is no injection related sub command in nova
> 
> any related URL will be very appreciate

The `nova` command interface is defined in:
https://github.com/openstack/python-novaclient/blob/master/novaclient/v1_1/shell.py
It would be good to have a man page for the `nova`
command that you could reference.

Anyway here is what you get when executing the
help for the 'boot' command:


# nova help boot
usage: nova boot [--flavor <flavor>] [--image <image>] [--meta <key=value>]
                 [--file <dst-path=src-path>] [--key_name <key_name>]
                 [--user_data <user-data>]
                 [--availability_zone <availability-zone>]
                 [--security_groups <security_groups>]
                 [--block_device_mapping <dev_name=mapping>]
                 [--hint <key=value>]
                 [--nic <net-id=net-uuid,v4-fixed-ip=ip-addr>]
                 [--config-drive <value>] [--poll]
                 <name>

Boot a new server.

Positional arguments:
  <name>                Name for the new server

Optional arguments:
  --flavor <flavor>     Flavor ID (see 'nova flavor-list').
  --image <image>       Image ID (see 'nova image-list').
  --meta <key=value>    Record arbitrary key/value metadata. May be give
                        multiple times.
  --file <dst-path=src-path>
                        Store arbitrary files from <src-path> locally to <dst-
                        path> on the new server. You may store up to 5 files.
  --key_name <key_name>
                        Key name of keypair that should be created earlier
                        with the command keypair-add
  --user_data <user-data>
                        user data file to pass to be exposed by the metadata
                        server.
  --availability_zone <availability-zone>
                        The availability zone for instance placement.
  --security_groups <security_groups>
                        comma separated list of security group names.
  --block_device_mapping <dev_name=mapping>
                        Block device mapping in the format <dev_name=<id>:<typ
                        e>:<size(GB)>:<delete_on_terminate>.
  --hint <key=value>    Send arbitrary key/value pairs to the scheduler for
                        custom use.
  --nic <net-id=net-uuid,v4-fixed-ip=ip-addr>
                        Create a NIC on the server. Specify option multiple
                        times to create multiple NICs. net-id: attach NIC to
                        network with this UUID (optional) v4-fixed-ip: IPv4
                        fixed address for NIC (optional).
  --config-drive <value>
                        Enable config drive
  --poll                Blocks while instance builds so progress can be
                        reported.


Here are the related APIs that are used by the command above:
http://docs.openstack.org/api/openstack-compute/2/content/CreateServers.html

So what happens when you present --meta options above?
That will bubble through the API to:
https://github.com/openstack/nova/blob/master/nova/virt/disk/api.py
If you look at _inject_metadata_into_fs() there, you can see
that a 'meta.js' file is written to the / directory.
Logic within the guest can then inspect that as required.

cheers,
Pádraig.