Local Testing with Docker

In this part, we will explain how to run the backend (FastAPI) and Streamlit chat UI together using Docker Compose for quick local testing.

Prerequisites

• Install Docker (Docker Desktop for Windows/macOS, or Docker Engine for Linux).
• (Optional) Create a .env file at the project root so environment variables are auto-loaded:

IONOS_API_KEY=your_ionos_key_here
TAVILY_API_KEY=your_tavily_key_here

On PowerShell you can also export them temporarily:

$env:IONOS_API_KEY = "your_ionos_key_here"
$env:TAVILY_API_KEY = "your_tavily_key_here"

Start Services

From the repository root (IONOS-simple-chatbot/):

docker compose up --build

What happens:

• Builds backend/ → image backend:latest exposing FastAPI at http://localhost:8000
• Builds frontends/streamlit-starter/ → image frontend:latest serving UI at http://localhost:8501

Verify

• Open http://localhost:8000/docs for the FastAPI Swagger UI
• Open http://localhost:8501 for the Streamlit chat interface

Stopping & Cleanup

Press Ctrl+C to stop. To also remove containers, network, and anonymous volumes:

docker compose down -v

Rebuild After Changes

If Python dependencies changed (e.g., edited requirements.txt):

docker compose build --no-cache backend-service
 docker compose up

Only code changes? Usually docker compose up --build is enough.

Troubleshooting