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Exercise 5: Provision a K3s cluster on an Elemental node

Time: 20 min
Previous: Exercise 4: Seed and boot nodes
Next: Exercise 6: Deploy workloads via Fleet

edge1 and edge2 are now running SL Micro. The elemental-register agent has phoned home and registered them with the Elemental Operator. But they are not yet Kubernetes nodes. That happens here.

5.1 Check MachineInventory

Watch for the registered nodes on the management cluster:

ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 \
  "kubectl get machineinventory -n fleet-default -w"

You should see one or two entries appear, one per node that has completed registration. Each row is a node that has proven its TPM identity and is now waiting to be told what to do.

In the Rancher UI: go to OS Management > MachineInventory. The same records appear there with hardware info, labels inherited from the MachineRegistration, and status.

5.2 Create a MachineInventorySelectorTemplate

This resource links a label selector to a machine pool. Any MachineInventory that matches the selector becomes a candidate node for a cluster:

cat << 'EOF' | ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 "kubectl apply -f -"
apiVersion: elemental.cattle.io/v1beta1
kind: MachineInventorySelectorTemplate
metadata:
  name: vertex-hub-selector
  namespace: fleet-default
spec:
  template:
    spec:
      selector:
        matchLabels:
          site-role: hub
EOF

5.3 Label edge1 for cluster assignment

Right now neither node matches site-role: hub. Label edge1 to trigger the match:

# Get edge1's MachineInventory name
EDGE1=$(ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 \
  "kubectl get machineinventory -n fleet-default \
   -o jsonpath='{.items[0].metadata.name}'")

echo "edge1 MachineInventory: $EDGE1"

# Label it
ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 \
  "kubectl label machineinventory $EDGE1 \
   -n fleet-default \
   site-role=hub \
   demo=true \
   edge-type=x86-cluster"

5.4 Create the cluster

Create a Cluster resource that uses the selector template as its machine pool:

cat << 'EOF' | ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 "kubectl apply -f -"
apiVersion: provisioning.cattle.io/v1
kind: Cluster
metadata:
  name: vertex-hub-01
  namespace: fleet-default
spec:
  kubernetesVersion: v1.35.3+k3s1
  rkeConfig:
    machinePools:
      - name: hub-nodes
        quantity: 1
        etcdRole: true
        controlPlaneRole: true
        workerRole: true
        machineConfigRef:
          kind: MachineInventorySelectorTemplate
          name: vertex-hub-selector
          apiVersion: elemental.cattle.io/v1beta1
EOF

5.5 Watch the cluster provision

In Rancher UI: go to Cluster Management. You will see vertex-hub-01 appear with status Provisioning. The management cluster is now remotely installing K3s on edge1 via the Elemental system agent.

From the terminal:

ssh -i /root/.ssh/id_ed25519 root@192.168.122.9 \
  "kubectl get cluster -n fleet-default -w"

Provisioning takes 5-10 minutes. When status changes to Active, the cluster is ready.

What just happened: you provisioned a Kubernetes cluster on a remote node without touching the node. The node registered itself, you applied a label, and the management cluster did the rest. This is the Elemental model for large-scale edge deployments.

Next: Exercise 6: Deploy workloads via Fleet