bakery-ia/gateway/app/main.py

"""
API Gateway - Central entry point for all microservices
Handles routing, authentication, rate limiting, and cross-cutting concerns
"""

import asyncio
import structlog
from fastapi import FastAPI, Request, HTTPException, Depends, WebSocket, WebSocketDisconnect
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
import httpx
import time
from typing import Dict, Any

from app.core.config import settings
from app.core.service_discovery import ServiceDiscovery
from app.middleware.auth import AuthMiddleware
from app.middleware.logging import LoggingMiddleware
from app.middleware.rate_limit import RateLimitMiddleware
from app.routes import auth, tenant, notification, nominatim, user
from shared.monitoring.logging import setup_logging
from shared.monitoring.metrics import MetricsCollector

# Setup logging
setup_logging("gateway", settings.LOG_LEVEL)
logger = structlog.get_logger()

# Create FastAPI app
app = FastAPI(
    title="Bakery Forecasting API Gateway",
    description="Central API Gateway for bakery forecasting microservices",
    version="1.0.0",
    docs_url="/docs",
    redoc_url="/redoc"
)

# Initialize metrics collector
metrics_collector = MetricsCollector("gateway")

# Service discovery
service_discovery = ServiceDiscovery()

# CORS middleware - Add first
app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS_LIST,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Custom middleware - Add in correct order (outer to inner)
app.add_middleware(LoggingMiddleware)
app.add_middleware(RateLimitMiddleware, calls_per_minute=300)
app.add_middleware(AuthMiddleware)

# Include routers
app.include_router(auth.router, prefix="/api/v1/auth", tags=["authentication"])
app.include_router(user.router, prefix="/api/v1/users", tags=["users"])
app.include_router(tenant.router, prefix="/api/v1/tenants", tags=["tenants"])
app.include_router(notification.router, prefix="/api/v1/notifications", tags=["notifications"])
app.include_router(nominatim.router, prefix="/api/v1/nominatim", tags=["location"])

@app.on_event("startup")
async def startup_event():
    """Application startup"""
    logger.info("Starting API Gateway")
    

    metrics_collector.register_counter(
        "gateway_auth_requests_total",
        "Total authentication requests"
    )
    metrics_collector.register_counter(
        "gateway_auth_responses_total", 
        "Total authentication responses"
    )
    metrics_collector.register_counter(
        "gateway_auth_errors_total",
        "Total authentication errors"
    )
    
    metrics_collector.register_histogram(
        "gateway_request_duration_seconds",
        "Request duration in seconds"
    )
    
    logger.info("Metrics registered successfully")
    
    metrics_collector.start_metrics_server(8080)
    
    logger.info("API Gateway started successfully")

@app.on_event("shutdown")
async def shutdown_event():
    """Application shutdown"""
    logger.info("Shutting down API Gateway")
    
    # Clean up service discovery
    # await service_discovery.cleanup()
    
    logger.info("API Gateway shutdown complete")

@app.get("/health")
async def health_check():
    """Health check endpoint"""
    return {
        "status": "healthy",
        "service": "api-gateway",
        "version": "1.0.0",
        "timestamp": time.time()
    }

@app.get("/metrics")
async def metrics():
    """Metrics endpoint for monitoring"""
    return {"metrics": "enabled"}

# ================================================================
# WEBSOCKET ROUTING FOR TRAINING SERVICE
# ================================================================

@app.websocket("/api/v1/ws/tenants/{tenant_id}/training/jobs/{job_id}/live")
async def websocket_training_progress(websocket: WebSocket, tenant_id: str, job_id: str):
    """WebSocket proxy that forwards connections directly to training service"""
    await websocket.accept()
    
    # Get token from query params
    token = websocket.query_params.get("token")
    if not token:
        logger.warning(f"WebSocket connection rejected - missing token for job {job_id}")
        await websocket.close(code=1008, reason="Authentication token required")
        return
    
    logger.info(f"Proxying WebSocket connection to training service for job {job_id}, tenant {tenant_id}")
    
    # Build WebSocket URL to training service
    training_service_base = settings.TRAINING_SERVICE_URL.rstrip('/')
    training_ws_url = training_service_base.replace('http://', 'ws://').replace('https://', 'wss://')
    training_ws_url = f"{training_ws_url}/api/v1/ws/tenants/{tenant_id}/training/jobs/{job_id}/live?token={token}"
    
    try:
        # Connect to training service WebSocket
        import websockets
        async with websockets.connect(training_ws_url) as training_ws:
            logger.info(f"Connected to training service WebSocket for job {job_id}")
            
            async def forward_to_training():
                """Forward messages from frontend to training service"""
                try:
                    async for message in websocket.iter_text():
                        await training_ws.send(message)
                except Exception as e:
                    logger.error(f"Error forwarding to training service: {e}")
            
            async def forward_to_frontend():
                """Forward messages from training service to frontend"""
                try:
                    async for message in training_ws:
                        await websocket.send_text(message)
                except Exception as e:
                    logger.error(f"Error forwarding to frontend: {e}")
            
            # Run both forwarding tasks concurrently
            await asyncio.gather(
                forward_to_training(),
                forward_to_frontend(),
                return_exceptions=True
            )
            
    except Exception as e:
        logger.error(f"WebSocket proxy error for job {job_id}: {e}")
        try:
            await websocket.close(code=1011, reason="Training service connection failed")
        except:
            pass
    finally:
        logger.info(f"WebSocket proxy closed for job {job_id}")

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)