Metrics

Prometheus metrics exposed by DriftQ-Core.

DriftQ-Core exposes /metrics in Prometheus text format. Use it to monitor reliability, lag, and backpressure in real time.

Endpoint:GET /metrics

Core metrics

inflight_messages{topic,group,partition}

Current number of leased (in-flight) messages.

consumer_lag{topic,group,partition}

Messages remaining after the committed offset (how far behind the group is).

dlq_messages_total{topic,reason}

Total number of messages routed to DLQ, labeled by reason.

produce_rejected_total{reason}

Total rejected produce attempts due to backpressure / overload (labeled by reason).

Quick usage

# view everything
curl -s "http://localhost:8080/metrics"

# quick filters (Windows)
curl -s "http://localhost:8080/metrics" | findstr consumer_lag

# quick filters (macOS/Linux)
curl -s "http://localhost:8080/metrics" | grep consumer_lag

Tip: Alert on sustained lag growth and DLQ increases — those usually mean real production issues.