gomon

Small Go service wired with OpenTelemetry metrics, an OTLP collector, and a Prometheus/Grafana front-end. Handy for verifying instrumentation patterns or trying out dashboard ideas before rolling them into real systems.

Ingredients

• Go HTTP handler exposes one endpoint, adds custom counters/histograms, and streams runtime stats via otelruntime (main.go).
• OTLP gRPC exporter feeds the collector, which batches and re-exports as a Prometheus target (otel-collector.yaml).
• Prometheus scrapes the collector (prometheus.yml) and Grafana provisions that datasource and optional dashboards on startup.
• Docker Compose connects the services, runs the app through Air for hot reloads, and stores Prometheus/Grafana data on volumes.

Quick start

docker compose up --build

When everything is running:

• App: http://localhost:8888 — each request increases http_requests_total and records latency.
• Prometheus: http://localhost:9090 — browse the collector-exported series (runtime metrics included).
• Grafana: http://localhost:3030 (admin/admin) — dashboards pick up the Prometheus datasource automatically.

Reference points

• main.go – instrumentation setup, runtime metrics, graceful shutdown.
• otel-collector.yaml – OTLP receiver + Prometheus exporter.
• prometheus.yml – scrape configuration.
• docker-compose.yml – service topology and env wiring.