Module metrics 

Prometheus metrics — install once, record per-request RED metrics.

Call init_metrics() from ArclyObservabilityPlugin::on_init. The returned PrometheusHandle is provided into the DI container so the /metrics route handler can call handle.render() to produce the scrape body.

Functions

init_metrics

Install the Prometheus metrics recorder globally and return a render handle.

metrics_route_handler

Build the axum route handler for GET /metrics.

record_request

Record one completed HTTP request into the global metrics recorder.