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Configure K3s and RKE2 internal and external IP addresses

K3s and RKE2 allow to specify the internal and external IP addresses of a node via the --node-ip and --node-external-ip parameters.

Rancher Provisioning allows to fill those parameters collecting the IP address from each node's network interface.

Anyway, the methods to collect those ip options for Custom Rancher Clusters and Elemental Rancher Clusters differ.

K3s and RKE2 internal and external IP addresses configuration in Rancher Cluster provisioning​

Rancher provisioning allows to specify in the Rancher Agent section the network interfaces that should be bound to the internal and external IP addresses of each provisioned node.

This is performed by adding the network interface names from which the IP addresses should be extracted in the CATTLE_INTERNAL_ADDRESS and the CATTLE_ADDRESS Agent Environment Variables (see Rancher docs).

note

The CATTLE_INTERNAL_ADDRESS and the CATTLE_ADDRESS Agent Environment Variables can be directly filled with the desired IP addresses. Anyway, since the internal and external IP addresses are per node, this would not work but for single node clusters.

warning

While during the creation of an Elemental Cluster it is possible to add Agent Environment Variables, the CATTLE_ADDRESS and the CATTLE_INTERNAL_ADDRESS ones are ignored and would not result in the configuration of the internal and external IP addresses of the provisioned nodes.

Configure K3s and RKE2 internal and external IP addresses in Elemental Clusters​

Elemental allows to configure the internal and external IP addresses of the Cluster Nodes attaching the elemental.cattle.io/InternalIP and elemental.cattle.io/ExternalIP labels to the MachineInventory resources tracking the target nodes.

These labels when attached to a MachineInventory resource are used to fill the internal and external IP addresses of the associated nodes.

The labels can be added to the MachineRegistration machineInventoryLabels fields, using the Network Label Template IP address variables as values, in order to allow to collect the IP addresses of each node.

Example: MachineRegistration where nodes will have the internal IP address set from interface eth0 and the external IP address from eth1.

registration.yaml
apiVersion: elemental.cattle.io/v1beta1
kind: MachineRegistration
metadata:
  name: fire-nodes
  namespace: fleet-default
spec:
  config:
    cloud-config:
      users:
        - name: root
          passwd: root
    elemental:
      install:
        reboot: true
        device: /dev/sda
        debug: true
  machineInventoryLabels:
    element: fire
    elemental.cattle.io/InternalIP: ${Network/NICs/eth0/IPv4Address}
    elemental.cattle.io/ExternalIP: ${Network/NICs/eth1/IPv4Address}