Ubuntu 20.04 LTS – cloud-init overrides static networking unexpectedly – 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

Static networking settings revert after reboot, causing address drift and unreachable services.

Environment & Reproduction

Seen on cloud images where cloud-init remains active after conversion to long-lived servers.

Root Cause Analysis

cloud-init network stage regenerates interface config from metadata and supersedes manual netplan.

Quick Triage

Check cloud-init status and inspect generated network files under runtime directories.

Step-by-Step Diagnosis

Trace which service writes current network config and compare timestamps across boot cycles.

Solution – Primary Fix

Disable cloud-init network config for persistent hosts and manage netplan directly.

Solution – Alternative Approaches

Maintain cloud-init ownership but update metadata templates through cloud control plane.

Verification & Acceptance Criteria

Network settings persist across multiple reboots with no unexpected cloud-init rewrites.

Rollback Plan

Re-enable cloud-init network module and restore previous cloud metadata behavior.

Prevention & Hardening

Define clear ownership of host networking and avoid mixed control paths.

Related Errors & Cross-Refs

Frequently linked to DHCP lease churn and duplicate address assignment incidents.

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

cloud-init networking documentation and Ubuntu cloud image operational practices.