motel: Preview Traffic

2026-02-22T09:00:00Z

motel preview renders the effective trace rate over time as an SVG chart, with scenario windows shaded and labelled. This is useful for verifying bursty patterns, scenario overrides, and ramp-up shapes before sending traffic to a collector.

For a self-contained report with the service map, operation calls, scenario changes, and captured traces, metrics, and logs, use motel preview --format html --run-duration 5s -o preview.html topology.yaml. The map shows the defined topology; the trace section and embedded JSON come from one bounded local run.

Uniform traffic

A flat rate produces a horizontal line across the chart.

motel preview --duration 5m docs/examples/traffic-patterns.yaml -o /tmp/uniform.svg
file /tmp/uniform.svg | grep -c 'SVG'

1

Diurnal traffic

A sine wave oscillating between trough (0.5x) and peak (1.5x) over a 24-hour period. The preview shows the full cycle.

cat > /tmp/diurnal.yaml << 'EOF'
version: 1
services:
  api:
    operations:
      request:
        duration: 10ms +/- 3ms
        calls:
          - database.query
  database:
    operations:
      query:
        duration: 5ms +/- 2ms
traffic:
  rate: 50/s
  pattern: diurnal
EOF
motel preview --duration 24h /tmp/diurnal.yaml -o /tmp/diurnal.svg
file /tmp/diurnal.svg | grep -c 'SVG'

1

Bursty traffic

Alternates between a base rate and periodic high-rate bursts. This example bursts to 5x every minute for 10 seconds.

cat > /tmp/bursty.yaml << 'EOF'
version: 1
services:
  api:
    operations:
      request:
        duration: 10ms +/- 3ms
        calls:
          - database.query
  database:
    operations:
      query:
        duration: 5ms +/- 2ms
traffic:
  rate: 50/s
  pattern: bursty
  burst_interval: 1m
  burst_duration: 10s
EOF
motel preview --duration 5m /tmp/bursty.yaml -o /tmp/bursty.svg
file /tmp/bursty.svg | grep -c 'SVG'

1

Bursty traffic with scenario overrides

The stress-test topology combines a bursty base pattern (500/s with 10x bursts) with two scenario overrides: a sustained peak at 5,000/s and an extreme burst at 1,000/s with 15x multiplier. Scenario windows appear as shaded rectangles.

motel preview --duration 3m docs/examples/stress-test.yaml -o /tmp/stress-test.svg
grep 'class="scenario-rect"' /tmp/stress-test.svg | wc -l | tr -d ' '

2

Inferred duration

Without --duration, motel infers a preview window from the topology's scenarios — the latest scenario end time plus a 10% buffer. Without scenarios, it defaults to 5 minutes.

motel preview docs/examples/stress-test.yaml -o /tmp/inferred.svg
head -1 /tmp/inferred.svg | grep -c '<svg'

1

Output options

Write to a file with -o, or pipe stdout to a file or viewer.

motel preview --duration 1m docs/examples/traffic-patterns.yaml | head -1 | grep -c '<svg'

1

The SVG is self-contained with inline styles and no external fonts. It renders on GitHub, in browsers, and in most image viewers.