Add TrafficDistribution field to describe service output

[08volt]

Motivation:

Kubernetes 1.31 introduced the TrafficDistribution field within the Service specification (spec.trafficDistribution). This field allows users to specify preferences for how traffic should be distributed among endpoints, such as the PreferClose option.

The official documentation describing this feature is here:
https://kubernetes.io/docs/reference/networking/virtual-ips/#traffic-distribution

Currently, kubectl describe service <service-name> does not display this field, even if it is set on the Service object.

Problem:

Users who configure spec.trafficDistribution on their Services lack a straightforward way to view or verify the applied setting using the standard kubectl describe command. They must resort to fetching the full YAML/JSON (kubectl get svc <service-name> -o yaml) and manually inspecting the spec.

Proposed Solution:

Modify the output of kubectl describe service to include the TrafficDistribution field when it is present and non-empty in the Service spec.

The output could look similar to how other optional spec fields like ExternalTrafficPolicy or InternalTrafficPolicy are displayed, for example:

...
Session Affinity: None
External Traffic Policy: Cluster
Internal Traffic Policy: Cluster
Traffic Distribution: PreferClose # <-- Add this line when field is set
HealthCheck NodePort:
Events:
...

Benefits:

• Increased Visibility: Provides users with a complete view of the Service configuration directly within the commonly used describe output.
• Easier Debugging: Helps users quickly verify the traffic distribution settings when diagnosing service routing behavior.
• Improved User Experience: Aligns kubectl describe with the API capabilities introduced in recent Kubernetes versions.

[mpuckett159]

/triage accept
We would accept a PR for this. The describe command output is rather straight forward as it just uses basic line printing.

[k8s-ci-robot]

@mpuckett159: The label(s) triage/accept cannot be applied, because the repository doesn't have them.

In response to this:

/triage accept
We would accept a PR for this. The describe command output is rather straight forward as it just uses basic line printing.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[mpuckett159]

/triage accepted

[tchap]

If you don't mind,

/assign

[08volt]

Thanks @tchap