///

## Write the callback documentation code { #write-the-callback-documentation-code }

This code won't be executed in your app, we only need it to *document* how that *external API* should look like.

  /**
   * Returns true if the request line should contain the full URL with host and port (like "GET
   * http://android.com/foo HTTP/1.1") or only the path (like "GET /foo HTTP/1.1").
   */
  private fun includeAuthorityInRequestLine(
    request: Request,
    proxyType: Proxy.Type,
  ): Boolean = !request.isHttps && proxyType == Proxy.Type.HTTP

  /**

```

</div>

In the output, there's a line with something like:

```hl_lines="4"
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

That line shows the URL where your app is being served, in your local machine.

### Check it { #check-it }

  /** A string like `GET` or `POST`. */
  public val method: String,
  /**
   * The request target from the original HTTP request.
   *
   * For origin-form requests this is a path like `/index.html`, that is combined with the `Host`
   * header to create the request URL.
   *
   * For HTTP proxy requests this will be either an absolute-form string like

    }
}
```

In this example, the "Proxy" could be something like **Traefik**. And the server would be something like FastAPI CLI with **Uvicorn**, running your FastAPI application.

### Providing the `root_path` { #providing-the-root-path }

To achieve this, you can use the command line option `--root-path` like:

<div class="termy">

```console

When we don't need to declare more validations or metadata, we can make the `q` query parameter required just by not declaring a default value, like:

```Python
q: str
```

instead of:

```Python
q: str | None = None
```

But we are now declaring it with `Query`, for example like:

//// tab | Annotated

```Python
q: Annotated[str | None, Query(min_length=3)] = None
```

////

It's relatively tightly coupled with relational databases (like MySQL or PostgreSQL), so, having a NoSQL database (like Couchbase, MongoDB, Cassandra, etc) as the main store engine is not very easy.

But that file doesn't exist, our dependencies are in a file at `app/dependencies.py`.

Remember how our app/file structure looks like:

<img src="/img/tutorial/bigger-applications/package.drawio.svg">

---

The two dots `..`, like in:

```Python
from ..dependencies import get_token_header
```

mean:

        assertEquals(UserAgentType.CHROME, userAgentHelper.getUserAgentType());
    }

    public void test_getUserAgentType_safariWithoutChrome() {
        getMockRequest().addHeader("user-agent",
                "Mozilla/5.0 (iPhone; CPU iPhone OS 14_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.1 Mobile/15E148 Safari/604.1");

  /**
   * The host address suitable for use with [InetAddress.getAllByName]. May be:
   *
   *  * A regular host name, like `android.com`.
   *
   *  * An IPv4 address, like `127.0.0.1`.
   *
   *  * An IPv6 address, like `::1`. Note that there are no square braces.
   *
   *  * An encoded IDN, like `xn--n3h.net`.
   *
   * | URL                   | `host()`        |
   * | :-------------------- | :-------------- |