```
curl http://minio1:9001/minio/health/cluster
HTTP/1.1 503 Service Unavailable
Accept-Ranges: bytes
Content-Length: 0
Server: MinIO
Vary: Origin
X-Amz-Bucket-Region: us-east-1
X-Minio-Write-Quorum: 3
X-Amz-Request-Id: 16239D6AB80EBECF
X-Xss-Protection: 1; mode=block
Date: Tue, 21 Jul 2020 00:36:14 GMT
```

### Cluster-readable probe

      if (!response.isSuccessful) throw IOException("Unexpected code $response")

      println("Server: ${response.header("Server")}")
      println("Date: ${response.header("Date")}")
      println("Vary: ${response.headers("Vary")}")
    }
  }
}

fun main() {
  AccessHeaders().run()

    }
  }

  /**
   * Initialize the cache. This will include reading the journal files from the storage and building
   * up the necessary in-memory cache information.
   *
   * The initialization time may vary depending on the journal file size and the current actual
   * cache size. The application needs to be aware of calling this function during the
   * initialization phase and preferably in a background worker thread.
   *

	// Note: The size of the security token that STS APIs return is not fixed. We
	// strongly recommend that you make no assumptions about the maximum size. As
	// of this writing, the typical size is less than 4096 bytes, but that can vary.
	// Also, future updates to AWS might require larger sizes.
	Credentials auth.Credentials `xml:",omitempty"`

	// A percentage value that indicates the size of the policy in packed form.

 *
 * Install OpenSC separately. On a mac `brew cast install opensc`.
 */
@SuppressSignatureCheck
class YubikeyClientAuth {
  fun run() {
    // The typical PKCS11 slot, may vary with different hardware.
    val slot = 0

    val config = "--name=OpenSC\nlibrary=/Library/OpenSC/lib/opensc-pkcs11.so\nslot=$slot\n"

    // May fail with ProviderException with root cause like

    cacheHit.cacheResponse()
      .assertCode(200)
      .assertHeader("Donut", "a")
      .assertHeader("ETag", "v1")
      .assertRequestUrl(server.url("/"))
      .assertRequestHeader("Accept-Language") // No Vary on Accept-Language.
      .assertRequestHeader("Accept-Charset", "UTF-8") // Because of Vary on Accept-Charset.

  }

  @Test
  fun varyMultipleFieldsWithMatch() {
    server.enqueue(
      MockResponse.Builder()
        .addHeader("Cache-Control: max-age=60")
        .addHeader("Vary: Accept-Language, Accept-Charset")
        .addHeader("Vary: Accept-Encoding")
        .body("A")
        .build(),
    )
    server.enqueue(
      MockResponse.Builder()
        .body("B")
        .build(),
    )

   */
  public static final String KEEP_ALIVE = "Keep-Alive";
  /**
   * The HTTP <a href="https://github.com/WICG/nav-speculation/blob/main/no-vary-search.md">{@code
   * No-Vary-Seearch}</a> header field name.
   *
   * @since 32.0.0
   */
  public static final String NO_VARY_SEARCH = "No-Vary-Search";
  /**
   * The HTTP <a href="https://googlechrome.github.io/OriginTrials/#header">{@code Origin-Trial}</a>
   * header field name.

    "Accept-Ranges": "bytes",
    "Content-Length": "0",
    "ETag": "4939450d1beec11e10a91ee7700bb593",
    "Server": "MinIO",
    "Strict-Transport-Security": "max-age=31536000; includeSubDomains",
    "Vary": "Origin,Accept-Encoding",
    "X-Amz-Request-Id": "16ABE7A785E7AC2C",
    "X-Amz-Server-Side-Encryption": "aws:kms",
    "X-Amz-Server-Side-Encryption-Aws-Kms-Key-Id": "arn:aws:kms:my-minio-key",

  @CheckForNull
  V forcePut(@ParametricNullness K key, @ParametricNullness V value);

  // Bulk Operations

  /**
   * {@inheritDoc}
   *
   * <p><b>Warning:</b> the results of calling this method may vary depending on the iteration order
   * of {@code map}.
   *
   * @throws IllegalArgumentException if an attempt to {@code put} any entry fails. Note that some