# Behind a Proxy { #behind-a-proxy }

In many situations, you would use a **proxy** like Traefik or Nginx in front of your FastAPI app.

These proxies could handle HTTPS certificates and other things.

## Proxy Forwarded Headers { #proxy-forwarded-headers }

Porque tenemos un proxy con un prefijo de path de `/api/v1` para nuestra aplicación, el frontend necesita obtener el esquema de OpenAPI en `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Navegador")
proxy["Proxy en http://0.0.0.0:9999/api/v1/app"]
server["Servidor en http://127.0.0.1:8000/app"]

browser --> proxy
proxy --> server
```

/// tip | Consejo

        Proxy(Proxy.Type.HTTP, InetSocketAddress.createUnresolved("proxy.example.com", 1003)),
        InetSocketAddress(ipv4Address, 1003),
      ).toString(),
    ).isEqualTo("example.com via proxy 1.2.3.4:1003")
    assertThat(
      Route(
        factory.newAddress(uriHost = "example.com", uriPort = 1003),

package okhttp3

import java.net.InetSocketAddress
import java.net.Proxy
import okhttp3.internal.toCanonicalHost

/**
 * The concrete route used by a connection to reach an abstract origin server. When creating a
 * connection the client has many options:
 *
 *  * **HTTP proxy:** a proxy server may be explicitly configured for the client. Otherwise, the

                    }

                    Proxy p = new Proxy();
                    p.setHost(proxy.getHost());
                    p.setProtocol(proxy.getProtocol());
                    p.setPort(proxy.getPort());
                    p.setNonProxyHosts(proxy.getNonProxyHosts());
                    p.setUserName(proxy.getUsername());
                    p.setPassword(proxy.getPassword());

    assertEquals(LIST1, ImmutableList.copyOf(newDelegatingListWithEquals(LIST1)));
  }

  public void testToString() {
    List<String> proxy = newDelegatingList(LIST1);
    assertEquals(Proxy.getInvocationHandler(proxy).toString(), proxy.toString());
  }

  interface A {}

  interface B {}

  public void testEquals() {
    new EqualsTester()
        .addEqualityGroup(newDelegatingList(LIST1))

 * limitations under the License.
 */
package okhttp3.internal.proxy

import java.io.IOException
import java.net.Proxy
import java.net.ProxySelector
import java.net.SocketAddress
import java.net.URI

/**
 * A proxy selector that always returns the [Proxy.NO_PROXY].
 */
object NullProxySelector : ProxySelector() {
  override fun select(uri: URI?): List<Proxy> {
    requireNotNull(uri) { "uri must not be null" }

    }

    return Selection(routes)
  }

  /** Prepares the proxy servers to try. */
  private fun resetNextProxy(
    url: HttpUrl,
    proxy: Proxy?,
  ) {
    fun selectProxies(): List<Proxy> {
      // If the user specifies a proxy, try that and only that.
      if (proxy != null) return listOf(proxy)

      // If the URI lacks a host (as in "http://</"), don't call the ProxySelector.

  /** Returns the client's proxy authenticator. */
  @get:JvmName("proxyAuthenticator") val proxyAuthenticator: Authenticator,
  /**
   * Returns this address's explicitly-specified HTTP proxy, or null to delegate to the
   * [proxy selector][proxySelector].
   */
  @get:JvmName("proxy") val proxy: Proxy?,
  protocols: List<Protocol>,
  connectionSpecs: List<ConnectionSpec>,
  /**

    return proxyClass.isInstance(arg)
        // Equal proxy instances should mostly be instance of proxyClass
        // Under some edge cases (such as the proxy of JDK types serialized and then deserialized)
        // the proxy type may not be the same.
        // We first check isProxyClass() so that the common case of comparing with non-proxy objects
        // is efficient.
        || (Proxy.isProxyClass(arg.getClass())