!!! tip
    The next sections are **not necessarily "advanced"**.

    And it's possible that for your use case, the solution is in one of them.

## Read the Tutorial first

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

```Dockerfile
FROM python:3.7

RUN pip install fastapi uvicorn

EXPOSE 80

COPY ./app /app

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "80"]
```

## Créer le code **FastAPI**.

* Créer un répertoire `app` et y entrer.
* Créez un fichier `main.py` avec :

```Python
from typing import Optional

from fastapi import FastAPI

app = FastAPI()


@app.get("/")

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.

You can read more about this in the [Advanced User Guide](../advanced/index.md){.internal-link target=_blank}.

## Details

### Providing the `root_path`

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

<div class="termy">

```console
$ fastapi run main.py --root-path /api/v1

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

If you use Hypercorn, it also has the option `--root-path`.

## The main `FastAPI`

Now, let's see the module at `app/main.py`.

Here's where you import and use the class `FastAPI`.

This will be the main file in your application that ties everything together.

And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI`

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

Die Datei `main.py` hätte als Inhalt:

```Python
{!../../../docs_src/async_tests/main.py!}
```

Die Datei `test_main.py` hätte die Tests für `main.py`, das könnte jetzt so aussehen:

```Python
{!../../../docs_src/async_tests/test_main.py!}
```

## Es ausführen

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

📁 `main.py` 🔜 ✔️:

```Python
{!../../../docs_src/async_tests/main.py!}
```

📁 `test_main.py` 🔜 ✔️ 💯 `main.py`, ⚫️ 💪 👀 💖 👉 🔜:

```Python
{!../../../docs_src/async_tests/test_main.py!}
```

## 🏃 ⚫️

👆 💪 🏃 👆 💯 🐌 📨:

<div class="termy">

```console

В вашем FastAPI приложении, импортируйте и вызовите `uvicorn` напрямую:

```Python hl_lines="1  15"
{!../../../docs_src/debugging/tutorial001.py!}
```

### Описание `__name__ == "__main__"`

Главная цель использования `__name__ == "__main__"` в том, чтобы код выполнялся при запуске файла с помощью:

<div class="termy">

```console
$ python myapp.py
```

</div>

## 🗄 ➕

🕐❔ 👆 📣 *➡ 🛠️* 👆 🈸, **FastAPI** 🔁 🏗 🔗 🗃 🔃 👈 *➡ 🛠️* 🔌 🗄 🔗.

!!! note "📡 ℹ"
    🗄 🔧 ⚫️ 🤙 <a href="https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#operation-object" class="external-link" target="_blank">🛠️ 🎚</a>.

⚫️ ✔️ 🌐 ℹ 🔃 *➡ 🛠️* &amp; ⚙️ 🏗 🏧 🧾.

⚫️ 🔌 `tags`, `parameters`, `requestBody`, `responses`, ♒️.

```Python hl_lines="11  19"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

### Check the automatic API docs

Now, run `uvicorn` with the main app, if your file is `main.py`, it would be:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>