Ubuntu 18.04 LTS Cloud-Init Rewrites Network Settings

📖 ~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 changes revert after reboot, causing recurring connectivity incidents.

Environment & Reproduction

Cloud instances on Ubuntu 18.04 where cloud-init remains authoritative for network config.

Root Cause Analysis

Cloud-init reapplies datasource-provided templates and overwrites local netplan edits.

Quick Triage

Confirm whether cloud-init is managing network by inspecting cloud-init status and generated files.

Step-by-Step Diagnosis

Inspect /etc/cloud and generated netplan files, then trace boot sequence for config regeneration.

Solution – Primary Fix

Disable cloud-init network management or adjust datasource metadata, then apply intended netplan profile.

Solution – Alternative Approaches

Adopt cloud-init templates as source of truth instead of local-only edits.

Verification & Acceptance Criteria

Network settings persist across reboot and match expected interface and route definitions.

Rollback Plan

Re-enable previous cloud-init behavior if disabling management introduces provisioning regressions.

Prevention & Hardening

Document ownership boundaries between cloud-init and local configuration management.

Related Errors & Cross-Refs

Cross-reference DHCP route conflicts and hostname reset issues on cloud images.

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

Consult cloud-init network configuration docs and Ubuntu cloud image guidance.