### What is "Mounting"

"Mounting" means adding a complete "independent" application in a specific path, that then takes care of handling all the sub-paths.

This is different from using an `APIRouter` as a mounted application is completely independent. The OpenAPI and docs from your main application won't include anything from the mounted application, etc.

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from docs_src.header_params.tutorial003 import app

client = TestClient(app)


@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"X-Token values": None}),
        ("/items", {"x-token": "foo"}, 200, {"X-Token values": ["foo"]}),
        (
            "/items",

            """
        ),
    ] = None,
    deprecated: Annotated[
        Union[deprecated, str, bool, None],
        Doc(
            """
            Mark this parameter field as deprecated.

            It will affect the generated OpenAPI (e.g. visible at `/docs`).
            """
        ),
    ] = None,
    include_in_schema: Annotated[
        bool,

These examples run the server program (e.g Uvicorn), starting **a single process**, listening on all the IPs (`0.0.0.0`) on a predefined port (e.g. `80`).

This is the basic idea. But you will probably want to take care of some additional things, like:

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

            "loc": [
                "path",
                "item_id"
            ],
            "msg": "value is not a valid integer",
            "type": "type_error.integer"
        }
    ]
}
```

car le paramètre de chemin `item_id` possède comme valeur `"foo"`, qui ne peut pas être convertie en entier (`int`).

La même erreur se produira si vous passez un nombre flottant (`float`) et non un entier, comme ici

    ```

=== "Python 3.8+"

    ```Python hl_lines="22"
    {!> ../../../docs_src/response_model/tutorial003.py!}
    ```

So, **FastAPI** will take care of filtering out all the data that is not declared in the output model (using Pydantic).

### `response_model` or Return Type

  direction: ltr;
  display: inline-block;
}

a.external-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0[↪]";
}

a.internal-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0↪";
}

.shadow {
  box-shadow: 5px 5px 10px #999;
}

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Top-level application

First, create the main, top-level, **FastAPI** application, and its *path operations*:

Schauen wir uns an, wie wir das machen können.

## pytest.mark.anyio

# About HTTPS

It is easy to assume that HTTPS is something that is just "enabled" or not.

But it is way more complex than that.

!!! tip
    If you are in a hurry or don't care, continue with the next sections for step by step instructions to set everything up with different techniques.

To **learn the basics of HTTPS**, from a consumer perspective, check <a href="https://howhttps.works/" class="external-link" target="_blank">https://howhttps.works/</a>.