BackendTLSPolicy TargetRef SectionName should support port name

[zhaohuabing]

What happened:

The LocalPolicyTargetReferenceWithSectionName requires the sectionName for Service to be the port name. However, port name is an optional feild in the Service spec. Instead, the port number should be used for the SectionName of Service, or ideally, both Port name and Port number could be supported as the sectionName for Service.

What you expected to happen:

LocalPolicyTargetReferenceWithSectionName uses port number for the SectionName for Service.

Related EG issue: envoyproxy/gateway#4769

[howardjohn]

Port is only optional if there is exactly 1 port IIRC, so technically you would not need sectionName in that case?

That being said, it may be more robust to explicitly target the single port, so that if an additional port is added later it isn't accidentally included?

[zhaohuabing]

Port is only optional if there is exactly 1 port IIRC, so technically you would not need sectionName in that case?

Ha, I haven't noticed that it's "conditional" optional, so technically we don't need sectionName for that :-)

That being said, it may be more robust to explicitly target the single port, so that if an additional port is added later it isn't accidentally included?

This kind of makes sense, but it's not a critical issue.

Additionally, since the BackendObjectReference API uses the port number , should the LocalPolicyTargetReferenceWithSectionName API also use the port number for consistency? It would also simplify the implementation, as it would allow directly matching a policy against the BackendRef without the need to resolve the service port to its name.

I'll keep this issue open for a while to allow for further discussion.