# modal.web_server

```python
def web_server(
    port: int,
    *,
    startup_timeout: float = 5.0,  # Maximum number of seconds to wait for the web server to start.
    label: Optional[str] = None,  # Label for created endpoint. Final subdomain will be <workspace>--<label>.modal.run.
    custom_domains: Optional[Iterable[str]] = None,  # Deploy this endpoint on a custom domain.
    requires_proxy_auth: bool = False,  # Require Modal-Key and Modal-Secret HTTP Headers on requests.
) -> Callable[[Union[_PartialFunction, NullaryFuncOrMethod]], _PartialFunction]:
```

Decorator that registers an HTTP web server inside the container.

This is similar to `@asgi_app` and `@wsgi_app`, but it allows you to expose a full HTTP server
listening on a container port. This is useful for servers written in other languages like Rust,
as well as integrating with non-ASGI frameworks like aiohttp and Tornado.

**Usage:**

```python
import subprocess

@app.function()
@modal.web_server(8000)
def my_file_server():
    subprocess.Popen("python -m http.server -d / 8000", shell=True)
```

The above example starts a simple file server, displaying the contents of the root directory.
Here, requests to the web endpoint will go to external port 8000 on the container. The
`http.server` module is included with Python, but you could run anything here.

Internally, the web server is transparently converted into a web endpoint by Modal, so it has
the same serverless autoscaling behavior as other web endpoints.

For more info, see the [guide on web endpoints](https://modal.com/docs/guide/webhooks).