Ubuntu 18.04 LTS – cloud-init keeps overwriting network config

📖 ~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

Manual network settings revert after reboot, causing inconsistent connectivity.

Environment & Reproduction

Typical on cloud images where cloud-init remains authoritative for networking.

Root Cause Analysis

cloud-init datasource metadata regenerates netplan files at boot.

Quick Triage

Check cloud-init status and identify which generated files overwrite local edits.

Step-by-Step Diagnosis

Review cloud-init logs, datasource data, and netplan generation history.

Solution – Primary Fix

Disable cloud-init network management or codify intended config in user-data.

Solution – Alternative Approaches

Create higher-priority netplan with managed lifecycle and cloud-init compatibility.

Verification & Acceptance Criteria

Network settings persist across reboot and cloud-init runs without drift.

Rollback Plan

Restore prior cloud-init config and generated network files if connectivity degrades.

Prevention & Hardening

Define ownership model for networking between cloud-init and config management.

Related Errors & Cross-Refs

Regenerated netplan files and datasource network-config override notices.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

cloud-init networking control and Ubuntu netplan integration docs.