How to set a custom hostname

When booting a host with an Elemental ISO, the hostname is temporarily set to rancher-{$RANDOM}. As soon as the boot process is finished, the registration phase takes place: the host connects to the Elemental Operator, which creates a MachineInventory for the host.

Each host registered with the Elemental Operator is tracked by a MachineInventory resource. The hostname of the host is eventually set to the name of the MachineInventory resource, during the Cluster provisioning phase (i.e., during k3s/RKE2 deployment on the host).

Default hostname

The default name assigned to the newly created MachineInventory is in the form m-{$UUID}. When the host is provisioned as part of a Cluster, the m-{UUID} hostname is set, overriding the previous rancher-{$RANDOM} hostname.

Set custom hostnames

The hostname can be specified setting the machineName field in the ‘MachineRegistration’ resource.

The hostname set in the machineName is expected to be in a template form, in order to be uniquely generated for each host using SMBIOS and Hardware Labels data.

important note

The machineName field in the MachineRegistration resource will be used as the blueprint not only for the hostname of the registering host, but also for the name of the MachineInventory resource created to track the host.

This means that if you don’t use a templated machineName such to generate a unique name for each host that will boot using the same MachineRegistration data (i.e., the same ISO), only the first registering host will be successful while the others will fail: the MachineInventory name must be unique.