Make missing node IPs in dual-stack mode a hard error

[twz123]

Description

The networking would be borked in that case, and diagnosing might be hard. Better to be vocal about it, and pointing users to the root cause more quickly.

See:

• Dual-stack IPv4/IPv6 networking with kube-router not working #5833

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Manual test
• Auto test added

Checklist

• My code follows the style guidelines of this project
• My commit messages are signed-off
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[ncopa]

I think the lookupNodeName better describes how the IPs are detected. So I think this is more readable:

diff --git a/pkg/component/worker/kubelet.go b/pkg/component/worker/kubelet.go
index 2287c43d5..666db7025 100644
--- a/pkg/component/worker/kubelet.go
+++ b/pkg/component/worker/kubelet.go
@@ -156,6 +156,8 @@ func (k *Kubelet) Start(ctx context.Context) error {
                        // addresses in the private function k8s.io/kubernetes/pkg/kubelet.validateNodeIP
                        // which won't be replicated here.
                        args["--node-ip"] = ipv4.String() + "," + ipv6.String()
+               } else {
+                       return fmt.Errorf("node name IP address lookup didn't return addresses for both families: IPv4: %v, IPv6: %v", ipv4, ipv6)
                }
        }
 

alternatively:

diff --git a/pkg/component/worker/kubelet.go b/pkg/component/worker/kubelet.go
index 2287c43d5..9c934557e 100644
--- a/pkg/component/worker/kubelet.go
+++ b/pkg/component/worker/kubelet.go
@@ -151,7 +151,10 @@ func (k *Kubelet) Start(ctx context.Context) error {
                ipv4, ipv6, err := lookupNodeName(ctx, k.NodeName)
                if err != nil {
                        logrus.WithError(err).Errorf("failed to lookup %q", k.NodeName)
-               } else if ipv4 != nil && ipv6 != nil {
+               } else if ipv4 == nil || ipv6 == nil {
+                       return fmt.Errorf("node name IP address lookup didn't return addresses for both families: IPv4: %v, IPv6: %v", ipv4, ipv6)
+
+               } else {
                        // The kubelet will perform some extra validations on the discovered IP
                        // addresses in the private function k8s.io/kubernetes/pkg/kubelet.validateNodeIP
                        // which won't be replicated here.

But that's just my humble opinion.

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[github-actions]

The PR is marked as stale since no activity has been recorded in 30 days

[github-actions]

The PR is marked as stale since no activity has been recorded in 30 days

[github-actions]

The PR is marked as stale since no activity has been recorded in 30 days

[github-actions]

This pull request has merge conflicts that need to be resolved.