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Random Template Variables​

Random template variables are built-in in the Elemental Operator.

They allow to include random Int, Hex or UUID values in custom label templates.

The values are computed on the fly during the label template variables rendering.

VariableDescription
${Random/UUID}random UUID (e.g., fd95324a-c26b-4e28-8727-1dcec293a0ec)
${Random/Hex/[1-32]}random hexadecimal string of the specified lenght (min 1, max 32)
${Random/Int/[MAXINT]random integer (min 0, max MAXINT-1)
Rendering Examples
template valuerendered value example
${Random/UUID}fd95324a-c26b-4e28-8727-1dcec293a0ec
${Random/Hex/12}acd231f222b8
${Random/Int/10000}9432

The Random Template Variables can be handy for generating custom hostnames to be assigned to the registering host.

Since the hostname must be unique and is assigned through the MachineRegistration spec.machineName field, Random variables can be used to ensure uniqueness of a group of host sharing the same custom prefix and/or suffix.

Check the HowTo/Customize hostname section for more information.

registration example Random template variables
apiVersion: elemental.cattle.io/v1beta1
kind: MachineRegistration
metadata:
  name: fire-nodes
  namespace: fleet-default
spec:
  machineName: "fire-node-${Random/Hex/12}"
  config:
    cloud-config:
      users:
        - name: root
          passwd: root
    elemental:
      install:
        reboot: true
        device: /dev/sda
        debug: true
  machineInventoryLabels:
    elemental.cattle.io/UUID: "${Random/UUID}"