<span style="background-color:#007166"><font color="#D3D7CF"> module </font></span>  🐍 main.py

     <span style="background-color:#007166"><font color="#D3D7CF"> code </font></span>  Importing the FastAPI app object from the module with the
             following code:

# 第一步

最簡單的 FastAPI 檔案可能看起來像這樣：

{* ../../docs_src/first_steps/tutorial001.py *}

將其複製到一個名為 `main.py` 的文件中。

執行即時重新載入伺服器（live server）：

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

```

</div>

/// note

The command `uvicorn main:app` refers to:

* `main`: the file `main.py` (the Python "module").
* `app`: the object created inside of `main.py` with the line `app = FastAPI()`.

It is equivalent to:

```Python
from main import app
```

///

<div class="termy">

```console
// এখনো আমরা এনভায়রনমেন্ট ভেরিয়েবল সেট করিনি
$ python main.py

// যেহেতু env var সেট করা হয়নি, তাই আমরা ডিফল্ট ভ্যালু পাচ্ছি

Hello World from Python

// কিন্তু আমরা প্রথমে যদি একটা এনভায়রনমেন্ট ভারিয়েবল তৈরি করে নেই
$ export MY_NAME="Wade Wilson"

// এবং তারপর আবার প্রোগ্রাটিকে কল করি
$ python main.py

// এখন এটি এনভায়রনমেন্ট ভেরিয়েবল রিড করতে পারবে

Hello Wade Wilson from Python

<div class="termy">

```console
// Aquí todavía no configuramos la env var
$ python main.py

// Como no configuramos la env var, obtenemos el valor por defecto

Hello World from Python

// Pero si creamos una variable de entorno primero
$ export MY_NAME="Wade Wilson"

// Y luego llamamos al programa nuevamente
$ python main.py

// Ahora puede leer la variable de entorno

Hello Wade Wilson from Python
```

<div class="termy">

```console
// Aqui ainda não definimos a env var
$ python main.py

// Por isso obtemos o valor padrão

Hello World from Python

// Mas se definirmos uma variável de ambiente primeiro
$ export MY_NAME="Wade Wilson"

// E executarmos o programa novamente
$ python main.py

// Agora ele pode ler a variável de ambiente

Hello Wade Wilson from Python
```

</div>

    Set<DependencyScope> dependencyScopes();

    PathScope MAIN_COMPILE = pathScope(
            "main-compile",
            ProjectScope.MAIN,
            DependencyScope.COMPILE_ONLY,
            DependencyScope.COMPILE,
            DependencyScope.PROVIDED);

    PathScope MAIN_RUNTIME =
            pathScope("main-runtime", ProjectScope.MAIN, DependencyScope.COMPILE, DependencyScope.RUNTIME);

    PathScope TEST_COMPILE = pathScope(

```

</div>

➡️ 👀 ⚫️❔ 🔠 👈 🎛 ⛓:

* `main:app`: 👉 🎏 ❕ ⚙️ Uvicorn, `main` ⛓ 🐍 🕹 📛 "`main`",, 📁 `main.py`. &amp; `app` 📛 🔢 👈 **FastAPI** 🈸.
    * 👆 💪 🌈 👈 `main:app` 🌓 🐍 `import` 📄 💖:

        ```Python
        from main import app
        ```

    * , ❤ `main:app` 🔜 🌓 🐍 `import` 🍕 `from main import app`.
* `--workers`: 🔢 👨‍🏭 🛠️ ⚙️, 🔠 🔜 🏃 Uvicorn 👨‍🏭, 👉 💼, 4️⃣ 👨‍🏭.

RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

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

# (2)!
CMD ["fastapi", "run", "main.py", "--port", "80"]
```

1. Copy the `main.py` file to the `/code` directory directly (without any `./app` directory).

2. Use `fastapi run` to serve your application in the single file `main.py`.

All the code blocks can be copied and used directly (they are actually tested Python files).

To run any of the examples, copy the code to a file `main.py`, and start `fastapi dev` with:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:solid">main.py</u>

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting development server 🚀