[client] add option to prevent remove peers and routes when management services are not available

[gamerslouis]

Describe your changes

NetBird clients rely on the management service and signal service to establish and maintain connections. When the management service is temporary unavailable, a NetBird client is unable to re-establish existing connections after an ICE disconnect.

Introduce a new environment variable option: NB_KEEP_CONNECTION_ON_MANAGEMENT_DOWN.

When this flag is enabled and the management service is unavailable:

• The client will not remove peers after an ICE disconnect.
• If a network route cannot select a new peer, the client will retain the existing peer instead of removing it.

Issue ticket number and link

Stack

Checklist

• [ ] Is it a bug fix
• [ ] Is a typo/documentation fix
• [x] Is a feature enhancement
• [ ] It is a refactor
• [ ] Created tests that fail without the change (if possible)

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Documentation

Select exactly one:

• [ ] I added/updated documentation for this change
• [x] Documentation is not needed for this change (explain why)

Docs PR URL (required if "docs added" is checked)

Paste the PR link from https://github.com/netbirdio/docs here:

Summary by CodeRabbit

• Bug Fixes

  • Improved connection stability during management server maintenance by preserving active endpoints and routes under specific conditions, preventing unnecessary disconnections when the management service is temporarily unavailable.

• New Features

  • Added configuration option to keep connections alive during management downtime scenarios.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai[bot]]

📝 Walkthrough

Walkthrough

The changes introduce a feature flag NB_KEEP_CONNECTION_ON_MANAGEMENT_DOWN that conditionally preserves network endpoints and routes when the management connection is down. A new environment variable reader function is added, and endpoint/route removal logic is guarded in connection and route management code based on this flag and connection state.

Changes

Cohort / File(s)	Summary
Environment Configuration client/internal/peer/env.go	Adds exported constant EnvKeepConnectionOnMgmtDown and new function IsKeepConnectionOnMgmtDown() to read the feature flag from environment, with logging support.
Connection & Route Management client/internal/peer/conn.go, client/internal/routemanager/client/client.go	Adds conditional guards that skip endpoint removal (onICEStateDisconnected, onRelayDisconnected) and route removal (recalculateRoutes) when the feature flag is enabled and management/signal states are not both connected.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• pappz

Poem

🐰 A flag arrives to save the day,
When management's far, connections stay!
Endpoints preserved, routes held tight,
Through cloudy downs, we keep the light. ✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main feature: adding an option to prevent peer and route removal when management services are unavailable.
Description check	✅ Passed	The description adequately explains the changes, motivation, and behavior of the new environment variable feature, with the checklist properly completed.

✨ Finishing touches

• [ ] 📝 Generate docstrings

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[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud