## PeerAuthentication and ztunnel

syntax = "proto2";

package k8s.io.api.authentication.v1alpha1;

import "k8s.io/api/authentication/v1/generated.proto";
import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/authentication/v1alpha1";

1. The `caClient` will be configured to use either JWT or mTLS authentication. For JWT authentication, gRPC's `PerRPCCredentials`
   is configured with a `TokenProvider` which handles the logic of adding the proper JWT to each request. mTLS is configured
   by a tls.Config that points to files on disk.

It should be noted there is a circular dependency with mTLS authentication; in order to fetch a certificate we need

 *
 * ### Server Authentication
 *
 * This is the most common form of TLS authentication: clients verify that servers are trusted and
 * that they own the hostnames that they represent. Server authentication is required.
 *
 * To perform server authentication:
 *
 *  * The server's handshake certificates must have a [held certificate][HeldCertificate] (a

syntax = "proto2";

package k8s.io.api.authentication.v1beta1;

import "k8s.io/api/authentication/v1/generated.proto";
import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/authentication/v1beta1";

sasl_username    (string)    username for SASL/PLAIN or SASL/SCRAM authentication
sasl_password    (string)    password for SASL/PLAIN or SASL/SCRAM authentication
sasl_mechanism   (string)    sasl authentication mechanism, default 'plain'
tls_client_auth  (string)    clientAuth determines the Kafka server's policy for TLS client auth
sasl             (on|off)    set to 'on' to enable SASL authentication
tls              (on|off)    set to 'on' to enable TLS

    * A cookie.
* `http`: standard HTTP authentication systems, including:
    * `bearer`: a header `Authorization` with a value of `Bearer ` plus a token. This is inherited from OAuth2.
    * HTTP Basic authentication.
    * HTTP Digest, etc.
* `oauth2`: all the OAuth2 ways to handle security (called "flows").
    * Several of these flows are appropriate for building an OAuth 2.0 authentication provider (like Google, Facebook, Twitter, GitHub, etc):

 *     .build();
 * ```
 *
 * The proxy authenticator may implement preemptive authentication, reactive authentication, or
 * both.
 *
 * Applications may configure OkHttp with an authenticator for origin servers, or proxy servers,
 * or both.
 *
 * ## Authentication Retries
 *
 * If your authentication may be flaky and requires retries you should apply some policy

    }
    for (i in 0 until methodCount) {
      val candidateMethod: Int = fromSource.readByte() and 0xff
      if (candidateMethod == METHOD_NO_AUTHENTICATION_REQUIRED) {
        selectedMethod = candidateMethod
      }
    }
    when (selectedMethod) {
      METHOD_NO_AUTHENTICATION_REQUIRED -> {
        fromSink.writeByte(VERSION_5)
        fromSink.writeByte(selectedMethod)
        fromSink.emit()
      }

```

Refer [Prometheus documentation](https://prometheus.io/docs/introduction/first_steps/) for more details.

### 2. Configure authentication type for Prometheus metrics

MinIO supports two authentication modes for Prometheus either `jwt` or `public`, by default MinIO runs in `jwt` mode. To allow public access without authentication for prometheus metrics set environment as follows.

```
export MINIO_PROMETHEUS_AUTH_TYPE="public"
minio server ~/test