dummy-otel

A simple OTEL-instrumented Python Flask app that generates traces, metrics, and logs for observability testing.

Features

• OpenTelemetry tracing via OTLP gRPC
• Metrics exported to Prometheus-compatible OTLP endpoint
• Structured logs exported via OTLP
• Exposes several endpoints for testing behavior

API Endpoints

Path	Description
/	Root message - Randomly fails (HTTP 500 or timeout)
/0/	Emits OTEL trace, metric & log
/health	Health check (200 OK)

The /0/ endpoint generates:

• A trace span (generate-trace-span)
• Metric: dummy_requests_total
• Log messages via OTLP

Built for Kubernetes observability pipelines with Grafana Alloy or any OTLP-compatible collector.

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Requirements

You must have Grafana Alloy (or any OTLP-compatible receiver) running and accessible at the configured endpoint.

In a Grafana Cloud Kubernetes Monitoring setup, this is usually:

grpc://grafana-k8s-monitoring-alloy-metrics.<namespace>.svc.cluster.local:4317

Alloy must support:

• OTLP/gRPC (4317)
• Prometheus metric scraping (via k8s.grafana.com/scrape: "true" annotation)
• Stdout logs (if Alloy is configured to collect pod logs)

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Usage

🐳 Run with Docker

Prebuilt multi-architecture Docker images are available on GitHub Container Registry (GHCR):

• https://github.com/marinnedea/dummy-otel/pkgs/container/dummy-otel

docker run -p 8000:8000 \
  -e OTEL_EXPORTER_OTLP_ENDPOINT=http://your-otel-collector:4317 \
  -e OTEL_EXPORTER_OTLP_PROTOCOL=grpc \
  ghcr.io/marinnedea/dummy-otel:latest

Platforms Supported

• linux/amd64
• linux/arm64

Pull Specific Version

docker pull ghcr.io/marinnedea/dummy-otel:latest

Build & Run Locally

docker build -t dummy-otel .
docker run -p 8000:8000 \
  -e OTEL_EXPORTER_OTLP_ENDPOINT=grpc://<your-alloy-host>:4317 \
  -e OTEL_EXPORTER_OTLP_PROTOCOL=grpc \
  dummy-otel

Then:

curl http://localhost:8000
curl http://localhost:8000/metrics

Or use the included poll-dummy-otel.sh script into a cronjob to run every minute and append output to a local log file.

Make it executable:

chmod +x $HOME/dummy-otel/poll-dummy-otel.sh

Then create a cronjob for it:

crontab -e

Warning

Make sure to replace kubectl with the full path (e.g., /usr/local/bin/kubectl) when used in cron jobs. Also, cron doesn’t run your shell profile (like .bashrc or .profile), so variables like $HOME may not be defined the way you expect in crontab -e. Use the full absolute path instead of $HOME!

* * * * * /home/your_user/dummy-otel/poll-dummy-otel.sh >> /path/to/dummy-otel/poll.log 2>&1

Deploy to Kubernetes

Use a Deployment like this:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dummy-otel
  namespace: dummy-otel
spec:
  replicas: 1
  selector:
    matchLabels:
      app: dummy-otel
  template:
    metadata:
      labels:
        app: dummy-otel
      annotations:
        k8s.grafana.com/scrape: "true"
    spec:
      containers:
        - name: dummy-otel
          image: ghcr.io/marinnedea/dummy-otel:latest
          ports:
            - containerPort: 8000
          env:
            - name: OTEL_EXPORTER_OTLP_ENDPOINT
              value: grpc://grafana-k8s-monitoring-alloy-metrics.my-pi-namespace.svc.cluster.local:4317
            - name: OTEL_EXPORTER_OTLP_PROTOCOL
              value: grpc

Status

Designed and tested on:

• Raspberry Pi 5/ ARM64
• K3s and Kubernetes
• Grafana Alloy and Grafana Cloud

To be used with:

• Grafana Alloy
• Grafana Tempo
• Grafana Loki
• Prometheus-compatible backend (via OTLP)

Results:

Metrics:

Logs:

Traces:

Related Projects

• OpenTelemetry Python SDK
• Prometheus Python client
• Grafana Alloy