This guide explains the steps for deploying a Streamlit application on an Ubuntu-based Hostinger VPS using Systemd for persistence, Poetry for dependency management, and Nginx for secure web access (HTTPS).

🚀 Phase 1: Server Setup and Application Preparation

This phase establishes the foundational environment and prepares your code.

Step 1: Install Core Tools and Poetry

• Action: Log in via SSH and install the necessary system packages and the Poetry package manager.

  ssh root@your_vps_ip
  sudo apt update && sudo apt upgrade -y
  sudo apt install python3 python3-pip git nginx curl -y
  curl -sSL <https://install.python-poetry.org> | python3 -
  

• Explanation: We install Python, Git, and Nginx (web server) and Poetry (dependency management) to ensure the environment is ready to host the app.

Step 2: Clone Repository and Install Dependencies

• Action: Clone your repository and use Poetry to create the virtual environment and install dependencies.

  cd /root/
  git clone <https://github.com/egorhowell/Prophet-Forecasting-For-Portfolio-Optimisation>
  cd Prophet-Forecasting-For-Portfolio-Optimisation
  poetry install
  

• Explanation: Poetry isolates your app's libraries, preventing version conflicts with other software on the VPS.

Step 3: Configure Supabase Credentials (.env)

• Action: Create the essential .env file in the project root and insert your Supabase credentials.

  # Ensure this command captures the correct variables from your shell
  echo "SUPABASE_URL=\\"$SUPABASE_URL\\"" > .env
  echo "SUPABASE_KEY=\\"$SUPABASE_KEY\\"" >> .env
  

• Explanation: The Systemd service cannot read the personal .bashrc file. This dedicated .env file is securely loaded by Systemd to inject secrets into the application environment.

⚙️ Phase 2: Systemd Service Configuration (The Persistence)

This phase ensures the app runs 24/7 in the background and restarts automatically if it fails.

Step 4: Create the Systemd Service File

• Action: Create the service file /etc/systemd/system/streamlit-app.service and populate it. **(Replace the ExecStart path with the output from Step 4).**BashIni, TOML

  sudo nano /etc/systemd/system/streamlit-app.service

  [Unit]
  Description=Streamlit App Service
  After=network.target
  
  [Service]
  User=root
  Group=root
  WorkingDirectory=/root/Prophet-Forecasting-For-Portfolio-Optimisation
  EnvironmentFile=/root/Prophet-Forecasting-For-Portfolio-Optimisation/.env
  
  # REPLACE THE PATH BELOW:
  ExecStart=/path/to/poetry/venv/bin/python -m streamlit run src/streamlit_app.py --server.port 8501 --server.address 0.0.0.0
  
  Restart=always
  
  [Install]
  WantedBy=multi-user.target
  

• Explanation: EnvironmentFile loads the credentials. Restart=always guarantees the app restarts automatically. The ExecStart command runs Streamlit on the internal port 8501.

Step 5: Enable and Start the Service

• Action: Reload Systemd, enable auto-start, and launch the service.

  sudo systemctl daemon-reload
  sudo systemctl enable streamlit-app.service # Enables auto-start on boot
  sudo systemctl start streamlit-app.service
  sudo systemctl status streamlit-app.service
  

• Explanation: The service is now managing the app, ensuring it runs persistently in the background.