Documentation incorrectly states no API server application/yaml support

[sftim]

This is a Bug Report

Problem:
Kubernetes' API server supports YAML (for encoding request bodies, or for a negotiated response format), but the documentation says it does not.

Proposed Solution:
Add a section within https://kubernetes.io/docs/reference/using-api/api-concepts/#alternate-representations-of-resources about application/yaml, and remove the note that says you can't use YAML.

Also see #48317 (comment)

Page to Update:
https://kubernetes.io/docs/reference/using-api/api-concepts/#alternate-representations-of-resources

Additional Information:
/language en
/kind bug
/triage accepted
/priority important-longterm
/wg api-expression

[tengqm]

Also the code returned when an unsupported media-type is specified should be 415. E.g.

{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {},
  "status": "Failure",
  "message": "the body of the request was in an unknown format - accepted media types include: application/json, application/yaml, application/vnd.kubernetes.protobuf",
  "reason": "UnsupportedMediaType",
  "code": 415
}

[sftim]

AIUI it's 415 for unacceptable request bodies, and 406 Not acceptable if you try something like:

GET /api/v1/pods HTTP/1.1
…
Accept: application/fictional

(ie, when there's an empty intersection between server supported response types and client accepted media types)

[tengqm]

Experiments showed that:

• Unacceptable Accept header leads to 406: Not Acceptable;
• Unacceptable Content-Type header leads to 415 UnsupportedMediaType.

[sftim]

/retitle Documentation incorrectly states no API server application/yaml support

Describing the bug, not the fix

[abhilasha2418]

/assign