Ubuntu 16.04 Cloud-Init Rewrites Network Settings Unexpectedly

📖 ~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

Custom network settings revert after reboot, causing intermittent connectivity and routing drift.

Environment & Reproduction

Occurs on cloud images where cloud-init networking remains enabled after manual edits.

Root Cause Analysis

Cloud-init datasource metadata regenerates interfaces configuration and overwrites local changes.

Quick Triage

Check cloud-init status, metadata source, and timestamps on interfaces configuration files.

Step-by-Step Diagnosis

Inspect cloud-init logs and rendered network templates to identify overwrite trigger path.

Solution – Primary Fix

Disable cloud-init network management or set persistent policy, then apply validated local config.

Solution – Alternative Approaches

Manage settings through cloud-init userdata instead of local file-only modifications.

Verification & Acceptance Criteria

Desired network configuration survives reboot and route behavior remains stable.

Rollback Plan

Re-enable prior cloud-init policy and restore backed up network files if needed.

Prevention & Hardening

Document ownership of network config layer and enforce one source of truth.

Related Errors & Cross-Refs

Related to DHCP lease churn and static route loss after reboot.

Related tutorial: View the step-by-step tutorial for Ubuntu 16.04 LTS.

View all Ubuntu 16.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Cloud-init networking modules and Ubuntu cloud image management documentation.