Example:

```sh

            "retry_host_predicate": [
             {
              "name": "envoy.retry_host_predicates.previous_hosts",
              "typed_config": {
               "@type": "type.googleapis.com/envoy.extensions.retry.host.previous_hosts.v3.PreviousHostsPredicate"
              }
             }
            ],
            "host_selection_retry_max_attempts": "5",
            "retriable_status_codes": [
             503
            ]

      throw failures.first()
    }
  }

  private fun testToAscii(
    input: String,
    output: String?,
    comment: String?,
  ) {
    val url = "https://$input/".toHttpUrlOrNull()
    assertThat(url?.host, name = comment ?: input).isEqualTo(output)
  }

// by sending a naked HTTP request with liveness checks.
func isServerResolvable(endpoint Endpoint, timeout time.Duration) error {
	serverURL := &url.URL{
		Scheme: endpoint.Scheme,
		Host:   endpoint.Host,
		Path:   pathJoin(healthCheckPathPrefix, healthCheckLivenessPath),
	}

	httpClient := &http.Client{
		Transport: globalInternodeTransport,
	}

	if ok {
		return rt
	}
	return nil
}

// Returns a minio-go Client configured to access remote host described by destDNSRecord
// Applicable only in a federated deployment
var getRemoteInstanceClient = func(r *http.Request, host string) (*miniogo.Core, error) {
	cred := getReqAccessCred(r, globalSite.Region())
	// In a federated deployment, all the instances share config files

🙆 📨 📨 `http` ⚖️ `ws` 🔜 ❎ 🔐 ⚖ ↩️.

```Python hl_lines="2  6"
{!../../docs_src/advanced_middleware/tutorial001.py!}
```

## `TrustedHostMiddleware`

🛠️ 👈 🌐 📨 📨 ✔️ ☑ ⚒ `Host` 🎚, ✔ 💂‍♂ 🛡 🇺🇸🔍 🦠 🎚 👊.

```Python hl_lines="2  6-8"
{!../../docs_src/advanced_middleware/tutorial002.py!}
```

📄 ❌ 🐕‍🦺:

	. "gorm.io/gorm/utils/tests"
)

var DB *gorm.DB
var (
	mysqlDSN     = "gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True&loc=Local"
	postgresDSN  = "user=gorm password=gorm dbname=gorm host=localhost port=9920 sslmode=disable TimeZone=Asia/Shanghai"
	sqlserverDSN = "sqlserver://sa:LoremIpsum86@localhost:9930?database=master"
	tidbDSN      = "root:@tcp(localhost:9940)/test?charset=utf8&parseTime=True&loc=Local"
)

// Not a local locker
func (c *lockRESTClient) IsLocal() bool {
	return false
}

// Close - marks the client as closed.
func (c *lockRESTClient) Close() error {
	return nil
}

// String - returns the remote host of the connection.
func (c *lockRESTClient) String() string {
	return c.connection.Remote
}

	if err != nil {
		log.Fatalf("Error parsing sts endpoint: %v", err)
	}
	copts := &minio.Options{
		Creds:  li,
		Secure: stsEndpointURL.Scheme == "https",
	}
	minioClient, err := minio.New(stsEndpointURL.Host, copts)
	if err != nil {
		log.Fatalf("Error initializing client: ", err)
	}

	// Use minIO Client object normally like the regular client.

 *
 * By orchestrating two different servers with the same port but different IP addresses, we can
 * test what OkHttp does when both are reachable, or if only one is reachable.
 *
 * This test only runs on host machines that have both IPv4 and IPv6 addresses for localhost.
 */
@Timeout(30)
class FastFallbackTest {
  @RegisterExtension
  val clientTestRule = OkHttpClientTestRule()