```

</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 👨‍🏭.

<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

!!! note "Nota"
    O comando `uvicorn main:app` se refere a:

    * `main`: o arquivo `main.py` (o "módulo" Python).
    * `app`: o objeto criado no arquivo `main.py` com a linha `app = FastAPI()`.
    * `--reload`: faz o servidor reiniciar após mudanças de código. Use apenas para desenvolvimento.

Na saída, temos:

    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

from docs_src.app_testing.tutorial002 import test_read_main, test_websocket


def test_main():
    test_read_main()


def test_ws():

<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

!!! note
    Câu lệnh `uvicorn main:app` được giải thích như sau:

    * `main`: tệp tin `main.py` (một Python "mô đun").
    * `app`: một object được tạo ra bên trong `main.py` với dòng `app = FastAPI()`.
    * `--reload`: làm server khởi động lại sau mỗi lần thay đổi. Chỉ sử dụng trong môi trường phát triển.

## 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`

<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>
<font color="#3465A4">INFO    </font> Resolved absolute path <font color="#75507B">/home/user/code/awesomeapp/</font><font color="#AD7FA8">main.py</font>

  tmp_dir=$(mktemp -d)
  cp "${src_jar}" "${tmp_dir}/orig.jar"
  pushd "${tmp_dir}"
  # Extract any src/ files
  jar -xf "${tmp_dir}/orig.jar" src/
  # Extract any org/ files under src/main/java
  (mkdir -p src/main/java && cd src/main/java && jar -xf "${tmp_dir}/orig.jar" org/)
  # Repackage src/
  jar -cMf "${tmp_dir}/new.jar" src
  popd
  cp "${tmp_dir}/new.jar" "${dest_jar}"
  rm -rf "${tmp_dir}"
}
DIR=$1

```

</div>

Let's see what each of those options mean:

* `main:app`: This is the same syntax used by Uvicorn, `main` means the Python module named "`main`", so, a file `main.py`. And `app` is the name of the variable that is the **FastAPI** application.
    * You can imagine that `main:app` is equivalent to a Python `import` statement like:

        ```Python
        from main import app
        ```

      <!-- NOTE: The first filter is deliberately defined by the child as well, so should not be added twice -->
      <filter>src/main/filters/child-a.properties</filter>
      <filter>src/main/filters/parent-c.properties</filter>
      <filter>src/main/filters/parent-b.properties</filter>
      <filter>src/main/filters/parent-d.properties</filter>
    </filters>
  </build>