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Lumen

Fast HTTP load testing CLI — dynamic templates, threshold-gated CI, and load curves.

Most load testers answer "how fast is my API?" Lumen also answers "did this release break performance?" — by letting you define pass/fail thresholds and wiring the exit code directly into CI.

lmn run -H https://api.example.com/orders \
  --header "Authorization: Bearer ${API_TOKEN}" \
  -f lmn.yaml
# exits 0 if thresholds pass, 2 if they fail

# lmn.yaml
execution:
  request_count: 1000
  concurrency: 50

thresholds:
  - metric: error_rate
    operator: lt
    value: 0.01        # < 1% errors
  - metric: latency_p99
    operator: lt
    value: 500.0       # p99 < 500ms

Key Features

  • Single binary — no runtime, no dependencies, install with cargo install lmn
  • Declarative YAML config — version-control your load test alongside your code
  • Threshold-gated CI — exit code 2 on failure, plug into any pipeline
  • Dynamic request bodies — per-request JSON generation with typed placeholders
  • Load curves — ramp VUs up and down over time with linear or step profiles
  • Response tracking — extract and aggregate fields from response bodies
  • OpenTelemetry — stream traces to Grafana, Tempo, or any OTLP backend

Where to go next