Creating the image file
Both files metadata and user data is needed to create a working cloud-init image.
The image is created using genisoimage following this general command:
genisoimage -output <name>.iso -volid cidata -joliet -rock </path/user-data> </path/meta-data>
An example of this command:
genisoimage -output nbos-firstboot-config.iso -volid cidata -joliet -rock user-data meta-data