Config Drive Extension#

Config_drive is a read-only configuration drive that is attached to server instances on boot. It is given the label config-2, and it shows up as a CDROM drive on the instance. It is especially useful in conjunction with cloud-init (a server bootstrapping application) and for passing large files to be used by your server.

To use the config drive, once it is attached to a server, you need to mount it. Mounting instructions vary by operating system. For some Linux operating systems, for example, you might issue the following two instructions:

$ mkdir -p /mnt/config
$ mount /dev/disk/by-label/config-2 /mnt/config

When a config drive is created, it is configured by data contained in one or both of the following arguments:


Contained in openstack/latest/user_data


If the content of the user_data file is not purely text, convert it by using base64 encoding to allow for proper transfer and storage. If your user_data needs to be encoded and isn’t, you’ll get an 400 Userdata content cannot be decoded message.

Encoded user-data is a base64 encoded string and adheres to one of a few specs (depending on the Linux distribution): the Ubuntu operating system

style and CoreOS-style.


Located in openstack/content/0000 with the path listed in the openstack/latest/meta_data.json file.

The following list shows files present in the config drive if both user-data and personality arguments are passed during server creation:

  • ec2/2009-04-04/meta-data.json

  • ec2/2009-04-04/user-data

  • ec2/latest/meta-data.json

  • ec2/latest/user-data

  • openstack/2012-08-10/meta_data.json

  • openstack/2012-08-10/user_data

  • openstack/content

  • openstack/content/0000

  • openstack/content/0001

  • openstack/latest/meta_data.json

  • openstack/latest/user_data