* Traefik (que también puede manejar la renovación de certificados)
* Caddy (que también puede manejar la renovación de certificados)
* Nginx
* HAProxy

## Let's Encrypt { #lets-encrypt }

Antes de Let's Encrypt, estos **certificados HTTPS** eran vendidos por terceros.

    }
    return InetAddress.getByAddress(reversed);
  }

  /**
   * Returns a new InetAddress that is one less than the passed in address. This method works for
   * both IPv4 and IPv6 addresses.
   *
   * @param address the InetAddress to decrement
   * @return a new InetAddress that is one less than the passed in address
   * @throws IllegalArgumentException if InetAddress is at the beginning of its range
   * @since 18.0

 * garbage-collected. That's why we are careful to make a {@code Runnable} that does not have a
 * reference to any {@code MyServer} instance.
 *
 * @author Bob Lee
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible
public class FinalizableReferenceQueue implements Closeable {
  /*

      stopwatch.sleepMillis(rate * 1000);
      limiter.setRate(rate);
      long burst = measureTotalTimeMillis(limiter, oneSecWorthOfWork, new Random());
      // we allow one second worth of work to go in a burst (i.e. take less than a second)
      assertThat(burst).isAtMost(1000);
      long afterBurst = measureTotalTimeMillis(limiter, oneSecWorthOfWork, new Random());
      // but work beyond that must take at least one second

      stopwatch.sleepMillis(rate * 1000);
      limiter.setRate(rate);
      long burst = measureTotalTimeMillis(limiter, oneSecWorthOfWork, new Random());
      // we allow one second worth of work to go in a burst (i.e. take less than a second)
      assertThat(burst).isAtMost(1000);
      long afterBurst = measureTotalTimeMillis(limiter, oneSecWorthOfWork, new Random());
      // but work beyond that must take at least one second

            // If this CAS succeeds, we know that the provided callable will never be invoked,
            // so when oldFuture completes it is safe to allow the next submitted task to
            // proceed. Doing this immediately here lets the next task run without waiting for
            // the cancelled task's executor to run the noop AsyncCallable.
            //
            // ---
            //

				err = io.ErrUnexpectedEOF
			}
			r.err = err
			return res, err
		}
		res = append(res, name)
	}
	return res, nil
}

// skip n entries on the input stream.
// If there are less entries left io.EOF is returned.
func (r *metacacheReader) skip(n int) error {
	r.checkInit()
	if r.err != nil {
		return r.err
	}
	if n <= 0 {
		return nil
	}
	if r.current.name != "" {
		n--

Vemos que vamos a necesitar algunas dependencias usadas en varios lugares de la aplicación.

Así que las ponemos en su propio módulo `dependencies` (`app/dependencies.py`).

Ahora utilizaremos una dependencia simple para leer un header `X-Token` personalizado:

{* ../../docs_src/bigger_applications/app_an_py39/dependencies.py hl[3,6:8] title["app/dependencies.py"] *}

/// tip | Consejo

//       metadata:
//         - key: content-type
//           value: image/* # match objects with 'content-type', all values starting with 'image/'
//       size:
//         lessThan: "10MiB" # match objects with size less than this value (e.g. 10MiB)
//         greaterThan: 1MiB # match objects with size greater than this value (e.g. 1MiB)
//       purge:

   * corrected sample standard deviation</a> of the values. If this dataset is a sample drawn from a
   * population, this is an estimator of the population standard deviation of the population which
   * is less biased than {@link #populationStandardDeviation()} (the unbiased estimator depends on
   * the distribution). The count must be greater than one.
   *