Cloud-Init Overwrites 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 netplan edits revert after reboot and static IP settings disappear.

Environment & Reproduction

Common on cloud images where cloud-init is still configured to manage networking.

Root Cause Analysis

Cloud-init regenerates network definitions at boot from datasource metadata, overriding local admin files.

Quick Triage

Confirm ownership of generated files before repeated netplan edits.

Step-by-Step Diagnosis

Check `/etc/netplan/50-cloud-init.yaml`, inspect `cloud-init status`, and review boot logs with `journalctl -u cloud-init -b`.

Solution – Primary Fix

Create `99-disable-network-config.cfg` to disable cloud-init network management, then define persistent netplan YAML and apply.

Solution – Alternative Approaches

Keep cloud-init enabled but set network data in metadata/user-data so generated config matches intent.

Verification & Acceptance Criteria

Reboot preserves expected interface addresses/routes; cloud-init no longer rewrites local network config.

Rollback Plan

Remove disable file, run `cloud-init clean`, and reboot to restore datasource-driven behavior.

Prevention & Hardening

Standardize image policy for cloud-init networking ownership across environments.

Related Errors & Cross-Refs

Unexpected DHCP fallback, route loss after reboot, and metadata connectivity issues.

Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.

View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

cloud-init networking docs and Ubuntu cloud image best practices.