Using tmux with Streamlit

At this point in the series, I know how to set up a Streamlit app in RunPod and share it via an HTTP Service link. 🥳

However, there is a problem with this setup. What happens if I close the terminal window running the Streamlit app? Or if my computer goes to sleep? Well, then the Streamlit app will stop running.

What I need is a way to persist the terminal session running Streamlit, even if I close the terminal window or my computer goes to sleep. What I need is tmux.

tmux to the rescue

tmux is an open-source terminal multiplexer. This means it allows one to run multiple, simultaneous terminal sessions in a single window.

Most importantly for the present purposes, terminal sessions started with tmux persist — I can detach from a tmux session and it will keep running in the background even if I close the terminal window. I can then reattach to it later to check on progress, make changes, or close it down. For a good primer on tmux see this video from typecraft.

Here's how to use tmux with a RunPod-hosted Streamlit app.

Steps: tmux with Streamlit on RunPod

1. Connect to the Pod from the terminal via SSH.

Clicking on the Pod shows the code I need to connect. Just paste it into the terminal.

2. Install tmux

apt-get update
apt-get install -y tmux

3. Create a new terminal session:

tmux new -s streamlit

I like to give my sessions a name, so I don't get confused later. I've called this one "streamlit."

4. Inside tmux, start the app:

./start_streamlit.sh

Following from the previous article in this series, I assume I started my tmux session form the /workspace folder on my Pod and I've already written a shell script (start_streamlit.sh) that starts the Streamlit app.

5. Detach from tmux session:

Hit ctrl+b on the keyboard, then type d.

In tmux, ctrl+b is the default prefix key. It acts as a trigger that alerts tmux to listen for a command. The d command tells tmux to "detach" from the current terminal session. After this, I should see something like

[detached (from session streamlit)]

Now the Streamlit app is safely running in the background and will continue so long as the Pod is active. I can exit my SSH from the Pod, close the terminal, and shut down my computer — my colleagues will still be able to access the running Streamlit app.

6. Reattach anytime:

tmux attach -t streamlit

Just replace "streamlit" with whatever I called the terminal session. I can also just type tmux attach and it will attach to the most recent session. Then, I can then see the Streamlit app running. To shut down the app, type exit while attached via tmux.