Run a Streamlit app
Getting an application running on Fly.io is essentially working out how to package it as a deployable image. Once packaged, it can be deployed to the Fly.io platform.
In this guide we’ll learn how to deploy a Streamlit application on Fly.io.
Streamlit turns data scripts into shareable web apps in minutes. All in pure Python. No front‑end experience required.
Spinning up a streamlit app takes no time at all!
Speedrun
First, install flyctl, the Fly.io CLI, and sign up to Fly.io if you haven’t already.
The fastest way to get a basic Streamlit server on Fly.io is to use our streamlit template:
git clone git@github.com:fly-apps/hello-streamlit.git streamlit-app
cd streamlit-app
fly launch --generate-name
Deploy a Streamlit from scratch
For managing our project, we use Poetry. For more information on the initial setup with poetry, refer to setting up a python environment.
We can initialize a new project like so:
poetry new streamlit-app
cd streamlit-app
If you’re using Poetry 2.0+ (the default when installed via pipx), the poetry shell command is no longer built in. Use poetry run to run commands (e.g., poetry run python main.py), or activate the environment with poetry env activate. See the initial setup guide for more details.
Then we have to add the streamlit dependency:
poetry add streamlit
Now, let’s create a simple streamlit app in main.py:
import streamlit as st
st.write('hello from fly.io')
We can then serve the development version of the app using the streamlit cli tool:
streamlit run main.py
This will display a ‘hello from fly.io!’ message when you visit the root URL.
Before deploying, we must add a bit of configuration to .streamlit/config.toml:
[server]
headless = true
This ensures that our app doesn’t give a prompt when we ship it.
And with that you can deploy the app!
fly launch
Scanning source code
Detected a streamlit app
Warning: This organization has no payment method, turning off high availability
Creating app in [redacted]/[app-name]
We're about to launch your app on Fly.io. Here's what you're getting:
Organization: Your Name (fly launch defaults to the personal org)
Name: [app-name] (derived from your directory name)
Region: Amsterdam, Netherlands (this is the fastest region for you)
App Machines: shared-cpu-1x, 1GB RAM (most apps need about 1GB of RAM)
Postgres: <none> (not requested)
Redis: <none> (not requested)
Sentry: false (not requested)
...
==> Building image
...
==> Building image with Docker
...
Watch your deployment at https://fly.io/apps/[app-name]/monitoring
...
Visit your newly deployed app at https://[app-name].fly.dev/
This will generate a fly.toml file with the configuration for your app and a Dockerfile that uses multi-stage builds.
Refer to the fly.toml docs for more configuration options.
To deploy a new version of your app, simply run fly deploy in the project directory.
You can check out the full (yet minimal) example in this GitHub repository for a reference.