RHEL 8 – nm-cloud-setup Introduces Unwanted Route Changes

📖 ~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

Default routes change unexpectedly, causing intermittent reachability to internal services.

Environment & Reproduction

Observed on cloud instances where nm-cloud-setup modifies NetworkManager profiles dynamically.

Root Cause Analysis

Metadata-driven route updates conflict with static enterprise network design.

Quick Triage

Compare active routes with expected policy and inspect nm-cloud-setup logs via journalctl.

Step-by-Step Diagnosis

Check systemctl status nm-cloud-setup and review NetworkManager profile route settings.

Solution – Primary Fix

Disable or tune nm-cloud-setup, then apply explicit routes and restart NetworkManager.

Solution – Alternative Approaches

Retain service but enforce route metrics and per-interface policy routing rules.

Verification & Acceptance Criteria

Routing table remains stable after reboot and cloud metadata refresh events.

Rollback Plan

Re-enable original nm-cloud-setup configuration if platform networking dependencies require it.

Prevention & Hardening

Include routing conformance checks in cloud-init and post-provision validation pipelines.

Related Errors & Cross-Refs

Asymmetric routing, intermittent packet loss, unexpected default gateway changes.

Related tutorial: View the step-by-step tutorial for rhel-8.

View all rhel-8 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL 8 cloud networking, NetworkManager, and route management references.