Ubuntu 20.04 LTS – kubelet fails to start due to cgroup driver mismatch – Fix & Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Node stays NotReady because kubelet fails during initialization.

Environment & Reproduction

Ubuntu 20.04 Kubernetes node after runtime or kubeadm config change.

Root Cause Analysis

kubelet expected driver differs from container runtime cgroup configuration.

Quick Triage

Check kubelet logs and runtime info for current cgroup driver values.

Step-by-Step Diagnosis

Audit kubelet config, runtime config, and systemd integration settings.

Solution – Primary Fix

Set matching cgroup driver on kubelet and runtime, restart services.

Solution – Alternative Approaches

Recreate node with standardized bootstrap config if drift is extensive.

Verification & Acceptance Criteria

kubelet remains healthy and node transitions to Ready state.

Rollback Plan

Reapply previous cluster config and runtime settings if instability persists.

Prevention & Hardening

Template kubeadm and runtime configs to prevent configuration divergence.

Related Errors & Cross-Refs

Docker daemon cgroup issues frequently accompany kubelet failures.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

View all Ubuntu 20.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Kubernetes node configuration guidance for Ubuntu environments.