UDP services may trigger unnecessary LoadBalancer updates

[feiskyer]

What happened:

While nothing changed to all LoadBalancer service specs, scaling node number or restart controller manager would trigger LoadBalancer update APIs. This is because EnableTCPReset value is different between expected LB rule and existing LB rule when the protocol is not TCP, and hence equalLoadBalancingRulePropertiesFormat() would treat the LB rule as updated.

And here are the related logs:

I0129 07:27:01.471484       1 azure_loadbalancer.go:1516] reconcileLoadBalancer for service(default/test): lb(test-rg/kubernetes) wantLb(true) resolved load balancer name
I0129 07:27:01.530862       1 azure_loadbalancer.go:2106] getExpectedLBRules lb name (kubernetes) rule name (a30cf55982b684c1993a23dd1e177c98-UDP-24899)
I0129 07:27:01.530954       1 azure_loadbalancer.go:1696] reconcileLoadBalancer for service (default/test)(true): lb rule(a30cf55982b684c1993a23dd1e177c98-UDP-24899) - dropping

What you expected to happen:

• EnableTCPReset should only be set in LB rule when the protocol is TCP.
• equalLoadBalancingRulePropertiesFormat should omit EnableTCPReset when protocol is not TCP.

How to reproduce it (as minimally and precisely as possible):

Create a UDP LoadBalancer service in the cluster and then restart controller manager. After a while, there would be new write operations in LoadBalancer activities （this could be observed on the Azure portal）.

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others:

[feiskyer]

/assign @lzhecheng

[k8s-ci-robot]

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In response to this:

/assign @lzhecheng

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[lzhecheng]

/assign