Antrea agent log is full of "Skipping invalid IP:"

[tnqn]

Describe the bug

It was found antrea-agent is full of the following logs:

E0902 10:26:12.929300       1 utils.go:164] Skipping invalid IP: 
E0902 10:26:12.929327       1 utils.go:164] Skipping invalid IP: 
E0902 10:26:12.929334       1 utils.go:164] Skipping invalid IP: 
E0902 10:26:12.929341       1 utils.go:164] Skipping invalid IP: 
E0902 10:27:12.929965       1 utils.go:164] Skipping invalid IP: 
E0902 10:27:12.929985       1 utils.go:164] Skipping invalid IP: 
E0902 10:27:12.929990       1 utils.go:164] Skipping invalid IP: 
E0902 10:27:12.929994       1 utils.go:164] Skipping invalid IP: 
E0902 10:28:12.933216       1 utils.go:164] Skipping invalid IP: 
E0902 10:28:12.933240       1 utils.go:164] Skipping invalid IP: 
E0902 10:28:12.933248       1 utils.go:164] Skipping invalid IP: 
E0902 10:28:12.933254       1 utils.go:164] Skipping invalid IP: 
E0902 10:29:12.934178       1 utils.go:164] Skipping invalid IP: 
E0902 10:29:12.934203       1 utils.go:164] Skipping invalid IP: 
E0902 10:29:12.934209       1 utils.go:164] Skipping invalid IP: 
E0902 10:29:12.934213       1 utils.go:164] Skipping invalid IP: 
E0902 10:30:12.935270       1 utils.go:164] Skipping invalid IP: 
E0902 10:30:12.935291       1 utils.go:164] Skipping invalid IP: 
E0902 10:30:12.935296       1 utils.go:164] Skipping invalid IP: 
E0902 10:30:12.935301       1 utils.go:164] Skipping invalid IP: 
E0902 10:31:12.935728       1 utils.go:164] Skipping invalid IP: 
E0902 10:31:12.935749       1 utils.go:164] Skipping invalid IP: 
E0902 10:31:12.935755       1 utils.go:164] Skipping invalid IP: 
E0902 10:31:12.935759       1 utils.go:164] Skipping invalid IP: 
E0902 10:32:12.936566       1 utils.go:164] Skipping invalid IP: 

It's hard to tell what's the IP used for from the log itself. But fortunately the function that prints the log is only called in two cases: when processing "service.Spec.ExternalIPs" and when processing "service.Status.LoadBalancer.Ingress.IP". K8s has a validation for the former so it's impossible to set empty ExternalIP. The latter could be empty if the LoadBalancer is DNS based. So it's likely the error logs were because there were DNS based LoadBalancer Services in the cluster.

To Reproduce

Create a DNS based LoadBalancer Service.

Versions:

• Antrea version (Docker image tag). ~1.8.0