Ubuntu 16.04 LTS Cloud-Init Rewrites Network Configuration

📖 ~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 disappear after reboot, causing repeated connectivity incidents.

Environment & Reproduction

Common on cloud images where cloud-init remains enabled for network provisioning.

Root Cause Analysis

cloud-init datasource metadata reasserts network configuration and overrides local edits.

Quick Triage

Check cloud-init status and inspect generated network files after reboot cycle.

Step-by-Step Diagnosis

Trace cloud-init logs, compare metadata inputs, and identify modules rewriting interface definitions.

Solution – Primary Fix

Disable or constrain cloud-init network modules and define persistent host-managed configuration.

Solution – Alternative Approaches

Template immutable network config from image pipeline and avoid in-place manual edits.

Verification & Acceptance Criteria

Network settings persist across multiple reboots and metadata refresh events.

Rollback Plan

Re-enable prior cloud-init behavior if platform provisioning workflows depend on it.

Prevention & Hardening

Document cloud-init ownership boundaries and lock config files against drift.

Related Errors & Cross-Refs

Related to hostname resets, SSH key regeneration, and metadata timeout boot delays.

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

See cloud-init module documentation and Ubuntu cloud image operation guides.