cloudinit/Documentation/cloud-config-locations.md

Cloud-Config Locations

Every CoreOS boot Cloud-Config tool looks for a config file to configure your host. Here is a list of locations which are used by the Cloud-Config utility, depending on your CoreOS platform:

• Mount point with config-2 label. It should contain a openstack/latest/user_data relative path. An absolute path inside CoreOS should look like /media/configvirtfs/openstack/latest/user_data. Usually used by cloud providers or in VM installations.
• FAT or ISO9660 filesystem with config-2 label. A /media/configdrive/ mount point should contain a /media/configdrive/openstack/latest/user_data absolute path to the config file. Usually used in VM installations.
• Kernel command line: cloud-config-url=http://example.com/user_data. You can find this string using this command cat /proc/cmdline. Usually used in PXE or iPXE boots.
• /var/lib/coreos-install/user_data when you install CoreOS manually using the coreos-install tool. Usually used in bare metal installations.
• OEM images use /usr/share/oem/cloud-config.yml path.
• Azure platform uses OEM path for first Cloud-Config initialization and then /var/lib/waagent/CustomData to apply your settings.
• DigitalOcean and EC2 use URLs to download Cloud-Config.

You can also run the coreos-cloudinit tool manually and provide a path to your custom Cloud-Config file:

sudo coreos-cloudinit --from-file=/home/core/cloud-config.yaml

This command will apply your custom cloud-config.