bakery-ia/services/demo_session/app/main.py

"""
Demo Session Service - Main Application
Manages isolated demo sessions with ephemeral data
"""

from fastapi import FastAPI, Request, Response
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
import structlog
from contextlib import asynccontextmanager
import os

from app.core import settings, DatabaseManager
from app.api import demo_sessions, demo_accounts, demo_operations, internal
from shared.redis_utils import initialize_redis, close_redis
from shared.monitoring.logging import setup_logging
from shared.monitoring.metrics import MetricsCollector, add_metrics_middleware
from shared.monitoring.system_metrics import SystemMetricsCollector

# OpenTelemetry imports
from opentelemetry import trace
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
from opentelemetry.instrumentation.redis import RedisInstrumentor
from opentelemetry.sdk.resources import Resource

# Configure OpenTelemetry tracing
def setup_tracing(service_name: str = "demo-session"):
    """Initialize OpenTelemetry tracing with OTLP exporter for Jaeger"""
    resource = Resource.create({"service.name": service_name})

    otlp_exporter = OTLPSpanExporter(
        endpoint=os.getenv("OTEL_EXPORTER_OTLP_ENDPOINT", "http://otel-collector.monitoring.svc.cluster.local:4317"),
        insecure=True
    )

    provider = TracerProvider(resource=resource)
    processor = BatchSpanProcessor(otlp_exporter)
    provider.add_span_processor(processor)
    trace.set_tracer_provider(provider)

    return provider

# Initialize tracing
tracer_provider = setup_tracing("demo-session")

# Setup logging
setup_logging("demo-session", getattr(settings, 'LOG_LEVEL', 'INFO'))
logger = structlog.get_logger()

# Initialize database
db_manager = DatabaseManager()


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Application lifespan handler"""
    logger.info("Starting Demo Session Service", version=settings.VERSION)

    # Initialize database
    db_manager.initialize()

    # Initialize Redis using shared implementation
    await initialize_redis(
        redis_url=settings.REDIS_URL,
        db=0,
        max_connections=50
    )

    # Initialize system metrics collection
    system_metrics = SystemMetricsCollector("demo-session")
    logger.info("System metrics collection started")

    # Note: Metrics are exported via OpenTelemetry OTLP to SigNoz - no metrics server needed
    logger.info("Metrics export configured via OpenTelemetry OTLP")

    logger.info("Demo Session Service started successfully")

    yield

    # Cleanup on shutdown
    await db_manager.close()
    await close_redis()

    logger.info("Demo Session Service stopped")


app = FastAPI(
    title="Demo Session Service",
    description="Manages isolated demo sessions for prospect users",
    version=settings.VERSION,
    lifespan=lifespan
)

# Instrument FastAPI with OpenTelemetry
FastAPIInstrumentor.instrument_app(app)

# Instrument httpx for outgoing requests
HTTPXClientInstrumentor().instrument()

# Instrument Redis
RedisInstrumentor().instrument()

# Initialize metrics collector
metrics_collector = MetricsCollector("demo-session")

# Add metrics middleware to track HTTP requests
add_metrics_middleware(app, metrics_collector)

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


@app.exception_handler(Exception)
async def global_exception_handler(request: Request, exc: Exception):
    """Global exception handler"""
    logger.error(
        "Unhandled exception",
        path=request.url.path,
        method=request.method,
        error=str(exc)
    )
    return JSONResponse(
        status_code=500,
        content={"detail": "Internal server error"}
    )


# Include routers
app.include_router(demo_sessions.router)
app.include_router(demo_accounts.router)
app.include_router(demo_operations.router)
app.include_router(internal.router)


@app.get("/")
async def root():
    """Root endpoint"""
    return {
        "service": "demo-session",
        "version": settings.VERSION,
        "status": "running"
    }


@app.get("/health")
async def health():
    """Health check endpoint"""
    from shared.redis_utils import get_redis_manager

    redis_manager = await get_redis_manager()
    redis_ok = await redis_manager.health_check()

    return {
        "status": "healthy" if redis_ok else "degraded",
        "service": "demo-session",
        "version": settings.VERSION,
        "redis": "connected" if redis_ok else "disconnected"
    }


# Note: Metrics are exported via OpenTelemetry OTLP to SigNoz
# The /metrics endpoint is not needed as metrics are pushed automatically


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(
        "app.main:app",
        host="0.0.0.0",
        port=8000,
        reload=settings.DEBUG,
        log_level=settings.LOG_LEVEL.lower()
    )