2.10. Providing User Data to Instances

The user-data key is a special key in the metadata service which holds a file that cloud aware applications within the guest instance can access.
This user-data can be put in a file on your local system and then passed in at instance creation with the flag --user-data <user-data-file> for example:
$ nova boot --image myCirrosImage --flavor 1 --user-data mydata.file