# Run and share Streamlit apps

This example shows you how to run a Streamlit app with `modal serve`, and then deploy it as a serverless web app.

![example streamlit app](./streamlit.png)

This example is structured as two files:

1. This module, which defines the Modal objects (name the script `serve_streamlit.py` locally).

2. `app.py`, which is any Streamlit script to be mounted into the Modal
   function ([download script](https://github.com/modal-labs/modal-examples/blob/main/10_integrations/streamlit/app.py)).

```python
import shlex
import subprocess
from pathlib import Path

import modal

```

## Define container dependencies

The `app.py` script imports three third-party packages, so we include these in the example's
image definition and then add the `app.py` file itself to the image.

```python
streamlit_script_local_path = Path(__file__).parent / "app.py"
streamlit_script_remote_path = "/root/app.py"

image = (
    modal.Image.debian_slim(python_version="3.11")
    .uv_pip_install("streamlit~=1.35.0", "numpy~=1.26.4", "pandas~=2.2.2")
    .add_local_file(
        streamlit_script_local_path,
        streamlit_script_remote_path,
    )
)

app = modal.App(name="example-serve-streamlit", image=image)

if not streamlit_script_local_path.exists():
    raise RuntimeError(
        "app.py not found! Place the script with your streamlit app in the same directory."
    )

```

## Spawning the Streamlit server

Inside the container, we will run the Streamlit server in a background subprocess using
`subprocess.Popen`. We also expose port 8000 using the `@web_server` decorator.

```python
@app.function()
@modal.concurrent(max_inputs=100)
@modal.web_server(8000)
def run():
    target = shlex.quote(streamlit_script_remote_path)
    cmd = f"streamlit run {target} --server.port 8000 --server.enableCORS=false --server.enableXsrfProtection=false"
    subprocess.Popen(cmd, shell=True)


```

## Iterate and Deploy

While you're iterating on your screamlit app, you can run it "ephemerally" with `modal serve`. This will
run a local process that watches your files and updates the app if anything changes.

```shell
modal serve serve_streamlit.py
```

Once you're happy with your changes, you can deploy your application with

```shell
modal deploy serve_streamlit.py
```

If successful, this will print a URL for your app that you can navigate to from
your browser 🎉 .