## 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`

因此，为了能够在同一个文件中使用它们，我们直接导入子模块：

```Python hl_lines="5" title="app/main.py"
{!../../../docs_src/bigger_applications/app/main.py!}
```

### 包含 `users` 和 `items` 的 `APIRouter`

现在，让我们来包含来自 `users` 和 `items` 子模块的 `router`。

```Python hl_lines="10-11" title="app/main.py"
{!../../../docs_src/bigger_applications/app/main.py!}
```

!!! info

<div class="termy">

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

# (1)
COPY ./main.py /code/

# (2)
CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "80"]
```

1. `main.py` 파일을 `/code` 디렉터리로 곧바로 복사합니다(`./app` 디렉터리는 고려하지 않습니다).

2. Uvicorn을 실행해 `app` 객체를 (`app.main` 대신) `main`으로 부터 불러오도록 합니다.

그 다음 Uvicorn 커맨드를 조정해서 FastAPI 객체를 불러오는데 `app.main` 대신에 새로운 모듈 `main`을 사용하도록 합니다.

## 배포 개념

    ```

 [CustomTrustJava]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/CustomTrust.java
 [CustomTrustKotlin]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/kt/CustomTrust.kt
 [CertificatePinningJava]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/CertificatePinning.java

## 👑 **FastAPI** 📱

& 🔜 📁 `sql_app/main.py` ➡️ 🛠️ & ⚙️ 🌐 🎏 🍕 👥 ✍ ⏭.

### ✍ 💽 🏓

📶 🙃 🌌 ✍ 💽 🏓:

=== "🐍 3️⃣.6️⃣ & 🔛"

    ```Python hl_lines="9"
    {!> ../../../docs_src/sql_databases/sql_app/main.py!}
    ```

=== "🐍 3️⃣.9️⃣ & 🔛"

    ```Python hl_lines="7"
    {!> ../../../docs_src/sql_databases/sql_app_py39/main.py!}
    ```

#### ⚗ 🗒

* `main`: fájl `main.py` (a Python "modul").
* `app`: a `main.py`-ban a `app = FastAPI()` sorral létrehozott objektum.
* `--reload`: kód változtatás esetén újra indítja a szervert. Csak fejlesztés közben használandó.

</details>

### Ellenőrizd

* `main`: el archivo `main.py` (el"modulo" de Python).
* `app`: el objeto creado dentro de `main.py` con la línea `app = FastAPI()`.
* `--reload`: hace que el servidor se reinicie después de cambios en el código. Esta opción solo debe ser usada en desarrollo.

</details>

### Revísalo

INFO:     Application startup complete.
```

</div>

<details markdown="1">
<summary>নির্দেশনা সম্পর্কে <code>uvicorn main:app --reload</code>...</summary>

`uvicorn main:app` নির্দেশনাটি দ্বারা বোঝায়:

- `main`: ফাইল `main.py` (পাইথন "মডিউল")।
- `app`: `app = FastAPI()` লাইন দিয়ে `main.py` এর ভিতরে তৈরি করা অবজেক্ট।
- `--reload`: কোড পরিবর্তনের পরে সার্ভার পুনরায় চালু করুন। এটি শুধুমাত্র ডেভেলপমেন্ট এর সময় ব্যবহার করুন।

You can use simple tools like `htop` to see the CPU and RAM used in your server or the amount used by each process. Or you can use more complex monitoring tools, which may be distributed across servers, etc.

## Recap