Prometheus

Prometheus needs no push gateway or backend credentials. The Helm chart selects it by default; the bare application defaults METRICS_REPORTER to none, so Docker and binary deployments must set METRICS_REPORTER=prometheus.

Enable

Replace the example broker address with one that resolves and is reachable from inside the Klag container. Use Docker network or service DNS for Kafka in another container, or host.docker.internal:9092 for Kafka exposed by the host.

docker run -e KAFKA_BOOTSTRAP_SERVERS=broker.example.com:9092 \
           -e METRICS_REPORTER=prometheus \
           -p 8888:8888 \
           themoah/klag:latest

Metrics are then served at http://localhost:8888/metrics in Prometheus text format.

Scrape config

scrape_configs:
  - job_name: klag
    metrics_path: /metrics
    static_configs:
      - targets: ['klag:8888']

On Kubernetes, the Helm chart can render a ServiceMonitor for the Prometheus Operator. See the chart’s values.yaml.

If /metrics returns 404 or Prometheus cannot discover the ServiceMonitor, see Troubleshooting.

What you get

All metrics are exposed with consumer_group, topic, and partition labels where applicable. Import the Grafana dashboard for ready-made panels.