Application set up

This section provides the steps to provision and structure a Python repository in GitHub. The objective here is not to deploy anything yet, but rather to set up a scaffolded project layout and code that adheres to DataOS Python Stack conventions.

Steps to provision a repository

The repository must be provisioned in a proper structure. Follow the steps below to provision a repository.

Step 1. Create/Select a Repository

Create or select a repository in GitHub or Bitbucket where you will add the Python code.

Step 2. Create base directory

Inside that repository, add a folder named app, which will include the Python script with a .py extension and a requirements file with a .txt extension.

python-stack/
└── app/                        # baseDir (referenced in service/stack manifest)
    ├── main.py                 # Application entry point (required)
    ├── requirements.txt        # Dependencies (required)
    └── .streamlit/             # Streamlit-specific configuration folder
        └── config.toml         # Custom Streamlit configuration

Required Files: At a minimum, the repo must include:

• main.py: Entry point script executed by the Stack.
• requirements.txt: Python dependencies in pip format.

Step 3. Add the Python code and dependencies

In the file with the .py extension, add your Python script. In requirements.txt, add the requirements to run that Python script.

Example:

main.py

import os
import sys
import streamlit as st

def run_app():
    st.set_page_config(page_title="Simple Calculator", layout="centered")

    st.title("Simple Calculator")
    st.caption("Minimal Streamlit app to demonstrate Python UI + requirements.txt")

    # Inputs
    a = st.number_input("First number", value=10.0)
    b = st.number_input("Second number", value=5.0)
    op = st.selectbox("Operation", ["add", "subtract", "multiply", "divide"])

    # Action
    if st.button("Compute"):
        if op == "add":
            result = a + b
        elif op == "subtract":
            result = a - b
        elif op == "multiply":
            result = a * b
        else:  # divide
            result = "Error: division by zero" if b == 0 else a / b

        st.success(f"Result: {result}")

def main():
    # Detect if running inside Streamlit; if not, relaunch with `streamlit run`
    if not os.environ.get("IS_RUNNING_STREAMLIT"):
        os.environ["IS_RUNNING_STREAMLIT"] = "1"
        script = os.path.abspath(__file__)
        os.execvpe(sys.executable, [sys.executable, "-m", "streamlit", "run", script], os.environ)
    else:
        run_app()

if __name__ == "__main__":
    main()

requirements.txt

streamlit==1.37.1

config.toml

# .streamlit/config.toml
[server]
port = 8050
address = "0.0.0.0"
baseUrlPath = "myapp"

Step 4. Push the changes

Once the repository and the code are ready to be deployed, push the changes by executing the commands below.

git add .
git commit -m "chore: provision repo with baseDir, starter script, and requirements file"
git push -u origin main

Next Step

After provisioning the repository, the next step is to configure the Python Service manifest file to execute the Python script.