If it doesn't receive it, it returns an HTTP 401 "Unauthorized" error.

And returns a header `WWW-Authenticate` with a value of `Basic`, and an optional `realm` parameter.

That tells the browser to show the integrated prompt for a username and password.

Then, when you type that username and password, the browser sends them in the header automatically.

## Simple HTTP Basic Auth

I'll also show you the **official Docker image** that includes **Gunicorn with Uvicorn workers** and some default configurations that can be useful for simple cases.

You have been reading here some of the main concepts that you would probably need to keep in mind when deciding how to deploy your application:

* Security - HTTPS
* Running on startup
* Restarts
* Replication (the number of processes running)
* Memory
* Previous steps before starting

from typing_extensions import Annotated, Doc


class HTTPException(StarletteHTTPException):
    """
    An HTTP exception you can raise in your own code to show errors to the client.

    This is for client errors, invalid authentication, invalid data, etc. Not for server
    errors in your code.

    Read more about it in the

FastAPI will now:

* **Validate** the data making sure that the max length is 50 characters
* Show a **clear error** for the client when the data is not valid
* **Document** the parameter in the OpenAPI schema *path operation* (so it will show up in the **automatic docs UI**)

## Alternative (old) `Query` as the default value

            - .github/workflows/build-docs.yml
            - .github/workflows/deploy-docs.yml
  langs:
    needs:
      - changes
    runs-on: ubuntu-latest
    outputs:
      langs: ${{ steps.show-langs.outputs.langs }}
    steps:
      - uses: actions/checkout@v4
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"
      - uses: actions/cache@v4

    You can set `"json_schema_extra"` with a `dict` containing any additional data you would like to show up in the generated JSON Schema, including `examples`.

=== "Pydantic v1"

But you can disable it by setting `syntaxHighlight` to `False`:

```Python hl_lines="3"
{!../../../docs_src/configure_swagger_ui/tutorial001.py!}
```

...and then Swagger UI won't show the syntax highlighting anymore:

<img src="/img/tutorial/extending-openapi/image03.png">

## Change the Theme

```Python hl_lines="3" title="app/routers/items.py"
{!../../../docs_src/bigger_applications/app/routers/items.py!}
```

#### How relative imports work

!!! tip
    If you know perfectly how imports work, continue to the next section below.

A single dot `.`, like in:

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

would mean:

    ```

!!! tip
    All this might seem contrived. And it might not be very clear how is it useful yet.

    These examples are intentionally simple, but show how it all works.

    In the chapters about security, there are utility functions that are implemented in this same way.