The API Server will no longer proxy non-101 responses for upgrade requests. This could break proxied backends (such as an extension API server) that respond to upgrade requests with a non-101 response code. ([#92941](https://github.com/kubernetes/kubernetes/pull/92941), [@tallclair](https://github.com/tallclair)) [SIG API Machinery]
 
## Changes by Kind

### Bug or Regression

  The API Server will no longer proxy non-101 responses for upgrade requests. This could break proxied backends (such as an extension API server) that respond to upgrade requests with a non-101 response code. ([#92941](https://github.com/kubernetes/kubernetes/pull/92941), [@tallclair](https://github.com/tallclair)) [SIG API Machinery]
 
## Changes by Kind

### API Change

- Kube-apiserver: fixes a 1.32+ regression validating OIDC and anonymous authentication flags are mutually exclusive to authentication configuration. Fixes an issue where the kube-apiserver `/flagz` endpoint would not respond correctly with parsed flags value. ([#130332](https://github.com/kubernetes/kubernetes/pull/130332), [@richabanker](https://github.com/richabanker)) [SIG API Machinery and Testing]

  The API Server will no longer proxy non-101 responses for upgrade requests. This could break proxied backends (such as an extension API server) that respond to upgrade requests with a non-101 response code. ([#92941](https://github.com/kubernetes/kubernetes/pull/92941), [@tallclair](https://github.com/tallclair)) [SIG API Machinery]

| token          | string     | Token from the AssumeRoleWithCustomToken call for external verification |

### Response

If the token is valid and access is approved, the plugin must return a `200` (OK) HTTP status code.

A `200 OK` Response should have `application/json` content-type and body with the following structure:

```json
{
    "user": <string>,
    "maxValiditySeconds": <integer>,

* `expose_headers` - Indica cualquier header de response que debería ser accesible para el navegador. Por defecto es `[]`.
* `max_age` - Establece un tiempo máximo en segundos para que los navegadores almacenen en caché los responses CORS. Por defecto es `600`.

El middleware responde a dos tipos particulares de request HTTP...

### Requests de preflight CORS

#### Load Balancing

En este caso, podrías querer documentar cómo esa API externa *debería* verse. Qué *path operation* debería tener, qué cuerpo debería esperar, qué response debería devolver, etc.

## Una aplicación con callbacks

Veamos todo esto con un ejemplo.

* Resolves an issue serving aggregated APIs backed by services that respond to requests to `/` with non-2xx HTTP responses ([#79895](https://github.com/kubernetes/kubernetes/pull/79895), [@deads2k](https://github.com/deads2k))

#### El tiempo de respuesta ayuda a los atacantes

En ese punto, al notar que el servidor tardó algunos microsegundos más en enviar el response "Nombre de usuario o contraseña incorrectos", los atacantes sabrán que acertaron en _algo_, algunas de las letras iniciales eran correctas.