Does Streamlit support the WSGI Protocol? (aka Can I deploy Streamlit with gunicorn?)

Problem

You're not sure whether your Streamlit app can be deployed with gunicorn.

Solution

Streamlit doesn't support the WSGI protocol, so you can't serve a Streamlit app with a WSGI server like gunicorn's default sync workers. Instead, Streamlit's server is an ASGI application built on Starlette. To serve your app with an ASGI server like Uvicorn, use st.App to create an ASGI app from your entrypoint file:

# app.py
import streamlit as st

app = st.App("streamlit_app.py")

Run Uvicorn from your app's directory. When you start your app with Uvicorn, Streamlit resolves a relative path passed to st.App against the current working directory. By default, Uvicorn only listens on 127.0.0.1:8000, so set the host and port explicitly:

uvicorn app:app --host 0.0.0.0 --port 8501

For more information, see App server.

Streamlit keeps each user's session, uploaded files, and media files in the memory of the server process that handles the session. If you run multiple worker processes that share a port (for example, gunicorn with several Uvicorn workers), requests from one session can reach a different process, which breaks file uploads, media, and reconnections. To scale your app, run separate replicas behind a proxy with session affinity. For more information, see Session affinity or stickiness.