SLE Micro / SL Micro¶

An immutable, transactional, minimal SUSE OS: read-only root (btrfs snapshots), transactional-update for atomic updates with rollback. Harvester's host OS is built on it.

Elemental¶

Kubernetes-native OS management:

• Build OS images as OCI container images (Dockerfile → bootable OS).
• MachineRegistration objects produce registration URLs/ISOs; machines boot, register, and appear as MachineInventory.
• MachineInventorySelectorTemplate lets Rancher provision RKE2/K3s clusters onto registered bare metal by label.
• ManagedOSImage performs OS upgrades across fleets.

Harvester's own installer and A/B upgrade mechanism descend from the same Elemental toolkit lineage.

System Upgrade Controller (SUC)¶

Plan-driven node upgrades used by Rancher for K3s/RKE2 and by Elemental:

apiVersion: upgrade.cattle.io/v1
kind: Plan
metadata:
  name: rke2-server
  namespace: system-upgrade
spec:
  concurrency: 1
  cordon: true
  nodeSelector:
    matchExpressions:
      - {key: node-role.kubernetes.io/control-plane, operator: Exists}
  serviceAccountName: system-upgrade
  upgrade:
    image: rancher/rke2-upgrade
  version: v1.34.10+rke2r1

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