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Generate synthetic OpenTelemetry data with telemetrygen

telemetrygen is the OpenTelemetry Collector Contrib data generator. It emits synthetic OTLP logs, traces and metrics, and exposes flags that let you shape the data: multiple services, log severities, span statuses and child spans, and different metric types. Use it to confirm that a ClickStack OpenTelemetry collector is accepting data and that varied, realistic events surface in the ClickStack UI.

This guide assumes the collector is already running with OTLP endpoints on 4317 (gRPC) and 4318 (HTTP).

Prerequisites​

This guide assumes you have completed the Getting Started Guide for Managed ClickStack and have an OpenTelemetry collector running with the OTLP gRPC (4317) and HTTP (4318) endpoints reachable from the machine you run telemetrygen on. If you secured the collector with an OTLP_AUTH_TOKEN, keep that value handy.

Install telemetrygen​

Run telemetrygen from its Docker image (no install required). Define a small wrapper so the commands below stay readable; --add-host lets the container reach a collector listening on the host:

telemetrygen() {
  docker run --rm --add-host=host.docker.internal:host-gateway \
    ghcr.io/open-telemetry/opentelemetry-collector-contrib/telemetrygen:latest "$@"
}
export OTEL_ENDPOINT=host.docker.internal:4317

Or install the binary with Go and target localhost instead:

go install github.com/open-telemetry/opentelemetry-collector-contrib/cmd/telemetrygen@latest
export OTEL_ENDPOINT=localhost:4317

Set environment variables​

Export the auth token if the collector is secured:

export OTLP_AUTH_TOKEN=<your_otlp_auth_token>
Unsecured collector

The ClickStack OpenTelemetry collector is unauthenticated by default. If you haven't followed Securing the collector to set an OTLP_AUTH_TOKEN, drop the --otlp-header line from the helper below.

Define a small tg helper so each command only specifies what varies (service, severity, status, attributes):

tg() { local signal=$1; shift; telemetrygen "$signal" \
  --otlp-endpoint ${OTEL_ENDPOINT} --otlp-insecure \
  --otlp-header "authorization=\"${OTLP_AUTH_TOKEN}\"" \
  --rate 5 --duration 30s "$@"; }

Generate logs​

Send logs as a realistic mix of severities across services, mostly informational with a warning and an error rather than one uniform stream:

tg logs --service frontend --severity-text Info  --severity-number 9  --body "GET /api/products 200" \
  --otlp-attributes 'deployment.environment="production"' \
  --telemetry-attributes 'http.method="GET"' --telemetry-attributes 'http.status_code="200"'
tg logs --service checkout --severity-text Warn  --severity-number 13 --body "retrying payment authorization" \
  --otlp-attributes 'deployment.environment="production"' \
  --telemetry-attributes 'http.method="POST"'
tg logs --service payment  --severity-text Error --severity-number 17 --body "payment gateway timeout" \
  --otlp-attributes 'deployment.environment="production"' \
  --telemetry-attributes 'http.status_code="500"'

The most useful log flags:

  • --service sets service.name so events are attributable to a service.
  • --severity-text and --severity-number set the level (severity-number ranges from 1 to 24).
  • --body sets the log message.
  • --otlp-attributes sets resource-level attributes (key="value", key=true, or key=<integer>).
  • --telemetry-attributes sets per-record attributes.

Generate traces​

Send multi-span traces from several healthy services plus one failing dependency. This gives the Service Map a realistic shape, mostly healthy with one erroring service, and populates the error views:

# Healthy services: the bulk of the traffic, all spans Ok
for svc in frontend checkout cart; do
  tg traces --service "$svc" --child-spans 3 --span-duration 80ms --status-code Ok \
    --otlp-attributes 'deployment.environment="production"' \
    --telemetry-attributes "http.route=\"/$svc\""
done

# One slow dependency returning errors
tg traces --service payment --child-spans 3 --span-duration 450ms --span-links 1 --status-code Error \
  --otlp-attributes 'deployment.environment="production"' \
  --telemetry-attributes 'http.route="/charge"'

The most useful trace flags:

  • --child-spans generates that many child spans per trace, giving each trace real depth.
  • --span-duration sets how long each span lasts (for example 120ms, 2s).
  • --status-code is one of Unset, Error, Ok (or 0, 1, 2). Use Error to exercise error views.
  • --span-links adds links between spans.
  • --workers runs several generators in parallel for a higher, more varied volume.

Generate metrics​

Send the three common metric types so dashboards have counters, gauges, and a distribution. Unlike some generators, telemetrygen honors --duration for metrics, so no manual stop is needed:

tg metrics --service frontend --metric-type Sum       --otlp-metric-name http.server.requests --aggregation-temporality cumulative
tg metrics --service frontend --metric-type Gauge     --otlp-metric-name system.memory.usage
tg metrics --service payment  --metric-type Histogram --otlp-metric-name http.server.duration

--metric-type accepts Gauge, Sum, Histogram, or ExponentialHistogram. --otlp-metric-name names the series so you can find it in the UI, and --aggregation-temporality is delta or cumulative.

Verify in ClickStack​

Open the ClickStack UI from the ClickHouse Cloud console. In the Search view, set the time range to Last 15 minutes and switch the source between Logs and Traces. Filter on ServiceName to see the frontend, checkout, cart, and payment services, and on SeverityText to find the warning and error log lines. Open a payment trace to see the child spans and the error status. Open the Chart Explorer, select Metrics, and chart one of the metric names you set above (for example http.server.requests) to verify metrics ingestion.