HTML reports & time-series charts

loadr report turns a summary JSON export into a single, self-contained HTML file you can share with people who don't run loadr. It contains:

• Time-series charts — throughput, response-time percentiles, active VUs and error rate plotted against elapsed run time.
• The aggregate tables — thresholds, checks, latency trends, and counters/rates/gauges, exactly as the console summary reports them.

The file references no external assets: the charts are inline SVG drawn by a small inline script, and all styling is inline CSS. It opens offline and is safe to attach to an email or commit to a repo.

Generating a report

loadr run --summary-export results.json test.yaml
loadr report results.json -o report.html

loadr report accepts any summary JSON produced by --summary-export, including one fetched from a controller's /api/runs/{id}/summary endpoint in distributed mode.

The charts

Four charts are rendered from the run timeline:

Each chart shares a hover crosshair: move the pointer over any chart and a dashed line tracks the nearest interval in all four charts at once, with the exact values for that instant printed beneath. This makes it easy to correlate, say, a latency spike with the moment VUs ramped up.

A ramping or spike profile produces the most interesting shape — see examples/24-timeseries-report.yaml, which warms up, spikes to ~5x load, then recovers.

How the timeline is captured

During a run the engine snapshots the aggregator once per snapshot interval (1 s by default; --snapshot-interval to change it). Each snapshot is reduced to one compact timeline point and appended to the summary. In distributed mode the controller samples the centrally merged snapshot at the same cadence, so the timeline reflects the whole fleet.

Timeline latency percentiles are the live, count-weighted merge across tag sets — accurate enough for visual analysis. The aggregate tables remain the exact end-of-run figures (merged from HDR histograms), so a threshold and its chart may differ by a hair; trust the table for pass/fail.

timeline in the results JSON

The summary export gains a top-level timeline array. It is additive — existing fields are unchanged, and reports from before this feature (no timeline) still render, just without charts.

{
  "name": "timeseries-report",
  "run_id": "...",
  "duration_secs": 50.0,
  "metrics": [ "..." ],
  "thresholds": [ "..." ],
  "snapshot": { "...": "final per-tag snapshot" },
  "timeline": [
    {
      "elapsed_secs": 1.0,
      "rps": 48.0,
      "iterations_ps": 24.0,
      "active_vus": 5.0,
      "error_rate": 0.0,
      "latency_avg": 12.4,
      "latency_p50": 9.0,
      "latency_p95": 31.0,
      "latency_p99": 58.0
    }
  ]
}

One point is emitted per snapshot interval, plus a trailing point covering the residual window so even sub-interval runs produce a timeline. The latency fields are omitted (rather than null) when there is no sample yet, so charts simply start once traffic begins.