getEndpoints uses service target port directly if it's a number and mismatch with port name in endpoint

[fatedier]

What this PR does / why we need it:

This PR avoid requests fail for a little while after changing service port name if service target port is a number.

Types of changes

• 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 change)

Which issue/s this PR fixes

fixes #7390

How Has This Been Tested?

Follow the steps described in linked issue.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

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[fatedier]

/assign @ElvinEfendi

[fatedier]

/kind feature

[tao12345666333]

Thanks for your contributions. The first thing to confirm is whether there will be side effects here

[fatedier]

I'm not sure if there could be a endpoint subsets with different port number and same port name. I think it will not appear because k8s service validation will reject duplicate port name values.

Howerver, endpoint validation doesn't validate this rule.

We can remove break here. It will not affect result but cost more compute resources.

What do you think?

[fatedier]

// EndpointPort is a tuple that describes a single port.
// +structType=atomic
type EndpointPort struct {
    // The name of this port.  This must match the 'name' field in the
    // corresponding ServicePort.
    // Must be a DNS_LABEL.
    // Optional only if one port is defined.
    // +optional
    Name string `json:"name,omitempty" protobuf:"bytes,1,opt,name=name"`

    // The port number of the endpoint.
    Port int32 `json:"port" protobuf:"varint,2,opt,name=port"`

    ...
}

// ServicePort contains information on service's port.
type ServicePort struct {
    // The name of this port within the service. This must be a DNS_LABEL.
    // All ports within a ServiceSpec must have unique names. When considering
    // the endpoints for a Service, this must match the 'name' field in the
    // EndpointPort.
    // Optional if only one ServicePort is defined on this service.
    // +optional
    Name string `json:"name,omitempty" protobuf:"bytes,1,opt,name=name"`

    // The IP protocol for this port. Supports "TCP", "UDP", and "SCTP".
    // Default is TCP.
    // +default="TCP"
    // +optional
    Protocol Protocol `json:"protocol,omitempty" protobuf:"bytes,2,opt,name=protocol,casttype=Protocol"`

    ...
}

From spec, EndpointPort name should match the 'name' of ServicePort, and ServicePort's name should be unique.

[fatedier]

I pushed a new commit to remove break here to avoid unknown problem.

[fatedier]

@tao12345666333 Do you have time to review this PR?

[tao12345666333]

sorry for delay. I will review it today.

/assign

[tao12345666333]

/ok-to-test

[fatedier]

@tao12345666333 Any progress?

[rikatz]

/lgtm
/approve
Thank you

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fatedier, rikatz

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