genx

genx is a lightweight CLI tool that generates time-series data following four curve types: cosine, linear, logarithmic, and exponential. It can route output to stdout, HTTP webhook, NATS, or MQTT. It also supports realtime mode so each data point is sent on predefined time internal.

Use cases

  • Feed a dashboard with simulated sensor data during a demo
  • Test a NATS or MQTT pipeline without physical IoT devices
  • Generate realistic load for observability and alerting tests
  • Simulate temperature, pressure, or any periodic signal

Use it 

# Cosine wave between 20°C and 30°C over 2 days, one point every 3 hours
docker run ghcr.io/lucj/genx -type cos -duration 2d -min 20 -max 30 -step 3h -period 1d

# Stream live data to a webhook in realtime
docker run ghcr.io/lucj/genx -type cos -min 18 -max 26 -duration 1h -step 10s --realtime \
  -output webhook -webhook-url http://myserver/ingest

End-to-end example with a containerised NATS server:

# 1. shared network
docker network create genx-net

# 2. NATS server
docker run -d --name nats --network genx-net nats

# 3. subscriber (another terminal)
docker run --rm --network genx-net natsio/nats-box \
    nats sub -s nats://nats:4222 sensors.temp

# 4. generate and publish
docker run --network genx-net ghcr.io/lucj/genx \
    -type linear -duration 1h -step 1m \
    -output nats -nats-url nats://nats:4222 -nats-subject sensors.temp

Source and full documentation on GitHub.