# metrics.py
from opentelemetry.metrics import set_meter_provider
from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.resources import SERVICE_NAME, Resource
from opentelemetry.exporter.prometheus import PrometheusMetricReader
from prometheus_client import make_asgi_app

# Set up Prometheus reader and meter provider
reader = PrometheusMetricReader()
provider = MeterProvider(
    metric_readers=[reader],
    resource=Resource.create({SERVICE_NAME: "fastapi-metrics-app"}),
)
set_meter_provider(provider)

# Expose the Prometheus metrics endpoint
metrics_app = make_asgi_app()  # Exposes /metrics