fix: avoid OVN northd "No path for static route" warning on startup

[oilbeater]

Summary

• Remove addNodeGatewayStaticRoute() from syncNodeRoutes() (init phase) and handleAddNode() where it ran before the join subnet's OVN Logical Router Port existed, causing OVN northd to warn: No path for static route 0.0.0.0/0 on router ovn-cluster; next hop 100.64.0.1
• Add LogicalSwitchExists check in handleAddOrUpdateVpc() to requeue the default VPC if the join subnet's logical switch is not yet ready, preventing the race between VPC worker and Subnet worker
• Remove the now-unused addNodeGatewayStaticRoute() function since handleAddOrUpdateVpc() already manages default route reconciliation via VPC route diffing

Root Cause

During controller startup, there were three places adding default gateway routes:

Location	Function	Timing	Safe?
Init phase	syncNodeRoutes() → addNodeGatewayStaticRoute()	Before workers start	❌ join LRP does not exist
VPC Worker	handleAddOrUpdateVpc()	Concurrent with Subnet Worker	⚠️ race condition
Node Worker	handleAddNode() → addNodeGatewayStaticRoute()	After subnet ready	✅ but redundant

The init phase call always triggered the warning. The VPC worker call could race with the Subnet worker.

Fix

• Init phase: Remove the route addition entirely — let the VPC worker handle it
• VPC worker: Check that the join logical switch exists before adding routes; requeue if not ready
• Node worker: Remove redundant call since VPC worker already reconciles all routes

On controller restart, the informer's initial list triggers enqueueAddVpc for the default VPC, and since OVN NB data is persistent, the join logical switch already exists — routes are added immediately without warnings.

Test plan

• make lint passes (0 issues)
• make ut passes (all packages ok)
• Verify no No path for static route warning in OVN northd logs after controller restart
• Verify default routes (0.0.0.0/0, ::/0) are present after fresh install and controller restart

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello @oilbeater, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a persistent warning in OVN northd ("No path for static route") that occurred during controller startup and node additions. The issue stemmed from static gateway routes being added before the corresponding OVN Logical Router Port for the join subnet was fully established, leading to unreachable next-hop errors. The solution refactors the route addition logic by centralizing default route reconciliation within the VPC worker, introducing a readiness check for the logical switch, and removing redundant route additions from the initialization and node handling phases. This ensures routes are only added when the OVN infrastructure is prepared, eliminating the warnings and streamlining the network configuration process.

Highlights

• Route Addition Refactoring: The addNodeGatewayStaticRoute() function call has been removed from the controller's initialization phase (syncNodeRoutes()) and the node handling logic (handleAddNode()) to prevent premature route additions before the necessary OVN Logical Router Port exists.
• VPC Worker Race Condition Fix: A LogicalSwitchExists check was introduced in handleAddOrUpdateVpc() to ensure the join subnet's logical switch is ready before attempting to add default routes, thereby preventing race conditions between the VPC and Subnet workers.
• Code Cleanup: The addNodeGatewayStaticRoute() function, now unused due to centralized route reconciliation in handleAddOrUpdateVpc(), has been completely removed.

Changelog

• pkg/controller/init.go
  • Removed the call to c.addNodeGatewayStaticRoute().
• pkg/controller/node.go
  • Removed the call to c.addNodeGatewayStaticRoute().
  • Removed the entire addNodeGatewayStaticRoute() function definition.
• pkg/controller/vpc.go
  • Added a check using c.OVNNbClient.LogicalSwitchExists() to verify the existence of the node's logical switch.
  • Implemented logic to requeue the VPC if the logical switch is not yet ready, preventing premature route additions.

Activity

• Verified that make lint passes with 0 issues.
• Verified that make ut passes for all packages.
• Pending verification for the absence of "No path for static route" warnings in OVN northd logs after controller restart.
• Pending verification for the presence of default routes (0.0.0.0/0, ::/0) after a fresh install and controller restart.

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[gemini-code-assist]

Code Review

This pull request effectively addresses the OVN northd warning on startup by refactoring the default route creation logic to avoid a race condition. The changes are clean and well-targeted. However, I've identified a potential regression in behavior. The removed addNodeGatewayStaticRoute function contained logic to avoid adding a default route if the user was managing static routes for the VPC. The new implementation in handleAddOrUpdateVpc appears to unconditionally add a default route, which could lead to conflicts with user-defined configurations. I've added a high-severity comment detailing this issue.

I am having trouble creating individual review comments. Click here to see my feedback.

pkg/controller/node.go (921-955)

By removing addNodeGatewayStaticRoute, the logic to avoid adding a default gateway route when a user provides their own static routes in the VPC spec is also removed. The previous implementation checked vpc.Spec.StaticRoutes and skipped adding a default route if it was user-managed. The new implementation in handleAddOrUpdateVpc unconditionally adds a default route for the default VPC. This could lead to conflicts with user-defined routes and represents a regression in behavior.

To fix this, the logic in handleAddOrUpdateVpc should be updated to check if a default route (0.0.0.0/0 or ::/0) already exists in vpc.Spec.StaticRoutes before adding its own.

[coveralls]

Pull Request Test Coverage Report for Build 22316478569

Details

• 0 of 8 (0.0%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 23.069%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/controller/vpc.go	0	8	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/controller/vpc.go	2	16.25%

Totals
Change from base Build 22313794790:	0.01%
Covered Lines:	12533
Relevant Lines:	54328

---

💛 - Coveralls