cloud-init rewrites netplan and breaks static IP

📖 ~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 static networking is overwritten on reboot by cloud-init network rendering.

Environment & Reproduction

Server boots with DHCP address despite edited /etc/netplan custom YAML.

Root Cause Analysis

Inspect /etc/cloud/cloud.cfg.d and /run/cloud-init for network config source precedence.

Quick Triage

cloud-init remains authoritative for network settings and regenerates netplan files each boot.

Step-by-Step Diagnosis

Disable cloud-init network config for the instance and place canonical static netplan in /etc/netplan.

Solution – Primary Fix

Reboot and confirm static address, gateway, and DNS values remain unchanged.

Solution – Alternative Approaches

Decide whether cloud-init or local netplan owns networking, then enforce one source of truth.

Verification & Acceptance Criteria

Re-enable cloud-init network handling if image lifecycle depends on dynamic provisioning.

Rollback Plan

Bake network ownership policy into golden image initialization templates.

Prevention & Hardening

cloud-init status –long; ls /etc/cloud/cloud.cfg.d; netplan get; netplan apply

Related Errors & Cross-Refs

Share instance metadata source, cloud-init logs, and current netplan files.

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

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References & Further Reading

Some cloud platforms inject DHCP-only assumptions that conflict with fixed addressing standards.