MicroK8s - Control Plane Scheduling Management

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🔒 1. Make Control Plane Node Unschedulable (Application Pods)

Prevent normal workloads from being scheduled on the control-plane node:

microk8s kubectl taint nodes {{ your-control-pane-node }} node-role.kubernetes.io/control-plane=:NoSchedule

What this does: - Blocks new pods from being scheduled there - Does NOT affect system pods - Does NOT remove existing pods

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🚚 2. Evict Existing Workloads from Control Plane

If application pods are already running on the control-plane node and you want to move them:

microk8s kubectl drain {{ your-control-pane-node }} --ignore-daemonsets --delete-emptydir-data

Options explained:

• --ignore-daemonsets → keeps DaemonSet pods (like ingress)
• --delete-emptydir-data → removes ephemeral storage data
• Pods will be rescheduled onto worker nodes (if replicas exist)

⚠️ Important: drain automatically cordons the node (marks it as unschedulable).
This prevents ANY new pods from being scheduled --- even those with tolerations.

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🔓 3. Re-Enable Scheduling on the Control Plane (Required After Drain)

After draining, if you still want specific pods to run there, you MUST uncordon the node:

microk8s kubectl uncordon {{ your-control-pane-node }}

Without this step, you may see errors like:

0/10 nodes are available: 1 node(s) were unschedulable

This error usually means the node is still cordoned.

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🔓 4. Allow Specific Pods to Still Run on Control Plane

If certain workloads must run on the control-plane node
(e.g., hostPath storage or special system workloads),

Add both:

• nodeAffinity (forces pod onto that node)
• toleration (allows pod to bypass the taint)

Example:

spec:
  # Allow pod to be scheduled even if node has NoSchedule taint
  tolerations:
  - key: "node-role.kubernetes.io/control-plane"
    operator: "Exists"
    effect: "NoSchedule"

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Undoing | Make Control Plane Fully Schedulable Again

🔁 1. Wish to Remove the Taint ?? (Make Control Plane Fully Schedulable Again)

If you want the control-plane node to behave like a normal worker again:

microk8s kubectl taint nodes {{ your-control-pane-node }} node-role.kubernetes.io/control-plane:NoSchedule-