launch.py

"""
launch.py

Launcher script to run both FastAPI backend and Streamlit frontend.
- For local development: Starts both services on different ports
- For Hugging Face Spaces: Configured to work with the Spaces proxy
"""

import os
import subprocess
import threading
import time
import signal
import sys

# Configuration
FASTAPI_PORT = 7860
STREAMLIT_PORT = 8501
IS_SPACE = "SPACE_ID" in os.environ  # Check if running on Hugging Face Spaces

# Define commands to run services
if IS_SPACE:
    # On Hugging Face Spaces, we need to bind to 0.0.0.0 to allow external access
    fastapi_cmd = ["python", "-m", "uvicorn", "api_backend:app", "--host", "0.0.0.0", "--port", str(FASTAPI_PORT)]
    streamlit_cmd = ["streamlit", "run", "app.py", "--server.address", "0.0.0.0", "--server.port", str(STREAMLIT_PORT)]
else:
    # For local development
    fastapi_cmd = ["python", "-m", "uvicorn", "api_backend:app", "--port", str(FASTAPI_PORT)]
    streamlit_cmd = ["streamlit", "run", "app.py", "--server.port", str(STREAMLIT_PORT)]

# Processes to track for cleanup
processes = []

# Signal handler for graceful shutdown
def handle_shutdown(signum, frame):
    print("\nShutting down all services...")
    for process in processes:
        if process.poll() is None:  # Check if process is still running
            process.terminate()
    sys.exit(0)

# Register signal handlers for graceful shutdown
signal.signal(signal.SIGINT, handle_shutdown)
signal.signal(signal.SIGTERM, handle_shutdown)

def run_service(cmd, service_name):
    """Run a service process and capture its output."""
    print(f"Starting {service_name}...")
    process = subprocess.Popen(
        cmd,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        universal_newlines=True,
        bufsize=1
    )
    processes.append(process)
    
    # Print process output with service identifier
    for line in process.stdout:
        print(f"[{service_name}] {line}", end="")
    
    # If we get here, the process has ended
    print(f"{service_name} has stopped.")

# Main execution
if __name__ == "__main__":
    print("🚀 Starting Flowchart-to-English services")
    
    # Start FastAPI in a separate thread
    fastapi_thread = threading.Thread(
        target=run_service,
        args=(fastapi_cmd, "FastAPI"),
        daemon=True
    )
    fastapi_thread.start()
    
    # Give FastAPI a moment to start up
    time.sleep(2)
    
    # Start Streamlit (in the main thread)
    run_service(streamlit_cmd, "Streamlit")