OpenTelemetry Demo Stack

This repository provides a local observability sandbox for traces, metrics, and logs using OpenTelemetry Collector plus Jaeger, Prometheus, Loki, and Grafana.

Architecture (Current)

Core services in docker-compose.yml:

• otel-collector (otel/opentelemetry-collector-contrib:0.87.0)
• jaeger (jaegertracing/all-in-one)
• prometheus (prom/prometheus)
• loki (grafana/loki)
• grafana (grafana/grafana)

Optional telemetry generators (defined, but disabled by default with scale: 0):

• telemetrygen-traces
• telemetrygen-metrics
• telemetrygen-logs

Telemetry flow:

• Apps or generators send OTLP to Collector (4317 gRPC / 4318 HTTP).
• Collector pipelines route:
  • traces -> otlp/jaeger (jaeger:4317) + debug
  • metrics -> prometheus exporter (:8889) + debug
  • logs -> loki exporter (http://loki:3100/loki/api/v1/push)
• Prometheus scrapes Collector endpoints:
  • internal Collector metrics: otel-collector:8888
  • exported metrics endpoint: otel-collector:8889

flowchart LR
  APP[Apps]
  TG[Telemetrygen<br/>traces / metrics / logs]
  OC[OpenTelemetry Collector]

  J[Jaeger]
  P[Prometheus]
  L[Loki]
  G[Grafana]

  APP -->|OTLP gRPC 4317<br/>OTLP HTTP 4318| OC
  TG -->|OTLP gRPC 4317| OC

  OC -->|traces<br/>otlp/jaeger| J
  OC -->|metrics exporter 8889| P
  OC -->|logs exporter| L

  P -->|datasource| G
  L -->|datasource| G

Loading

Exposed Ports

• Collector OTLP gRPC: 4317
• Collector OTLP HTTP: 4318
• Collector internal metrics: 8888
• Collector Prometheus exporter metrics: 8889
• Collector health check: 13133
• Collector zPages: 55679
• Jaeger UI: 16686
• Jaeger gRPC collector: 14250
• Jaeger HTTP collector: 14268
• Jaeger Zipkin-compatible ingest: 9411
• Prometheus UI: 9090
• Loki API: 3100
• Grafana UI: 3000

Note: Collector pprof extension is enabled on 1777 but not published to the host in Compose.

Repository Structure

.
├── docker-compose.yml
├── otel-collector-config.yaml
├── prometheus.yml
├── loki-config.yaml
├── LICENSE
└── README.md

Usage

1. Start core stack:

docker compose up -d

2. (Optional) Start telemetry generators:

docker compose up -d telemetrygen-traces telemetrygen-metrics telemetrygen-logs

3. Check status:

docker compose ps

4. Stop everything:

docker compose down

Access

• Jaeger: http://localhost:16686
• Prometheus: http://localhost:9090
• Grafana: http://localhost:3000 (login: admin / admin)
• Loki API: http://localhost:3100

OTLP Endpoints for Your Apps

• gRPC: localhost:4317
• HTTP: http://localhost:4318

Configuration Notes

• Collector receivers: OTLP gRPC + HTTP
• Collector processors: memory_limiter, batch (resourcedetection is defined but not wired into pipelines)
• Collector extensions: health_check, pprof, zpages
• Prometheus config scrapes only Collector endpoints (not app endpoints directly)
• Loki runs with local filesystem + boltdb-shipper settings for development

Troubleshooting

• Collector not running: docker logs otel-collector
• No traces in Jaeger: confirm otel-collector can reach jaeger:4317 and traces generator is running
• No metrics in Prometheus: check http://localhost:9090/targets
• No logs in Loki/Grafana: confirm logs generator is running and Collector logs pipeline is healthy
• Generators not sending data: they are disabled by default; start them explicitly

References

• OpenTelemetry Collector: https://opentelemetry.io/docs/collector/
• Telemetrygen: https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/cmd/telemetrygen
• Jaeger: https://www.jaegertracing.io/
• Prometheus: https://prometheus.io/
• Loki: https://grafana.com/oss/loki/
• Grafana: https://grafana.com/