| name | scenario-composer |
| description | Compose deterministic DSDS simulation scenarios from resilience hypotheses, load-test goals, or failure drills. Use when defining workload plus fault plus invariant bundles, built-in presets, and chaos experiments with reproducible seeds and explicit pass/fail criteria. |
Scenario Composer
Overview
Design reproducible scenarios that test one clear system behavior at a time. Package each scenario with deterministic timing, explicit hypotheses, and measurable success criteria.
Workflow
- Define experiment intent
- Write one hypothesis in observable terms.
- Choose the primary target metric (
p99 latency, error rate, recovery time, or cost).
- Freeze deterministic controls
- Set
seed, simulationDuration, and warmupDuration.
- Avoid changing more than one major variable per scenario version.
- Compose traffic profile
- Select one workload pattern and justify it (
constant, poisson, spike, diurnal, bursty, sawtooth, replay).
- Define request mix and base load.
- For scale tests, define the step-up schedule and stop condition.
- Compose failure and resilience conditions
- Inject the minimum fault set needed to test the hypothesis.
- Specify timing mode (
deterministic, probabilistic, conditional) and fault duration.
- Include resilience controls relevant to the scenario (retry, breaker, bulkhead, rate limit).
- Define checks and expected outcomes
- Add invariants and SLO checks that can fail the run.
- Record expected qualitative behavior (for example, queue growth at gateway before API timeout cascade).
- Deliver scenario package
- Provide scenario name and intent, topology deltas (or full config), workload config, fault list, invariants, and pass/fail rubric.
Scenario quality rules
- Keep each scenario focused on one dominant failure pattern.
- Separate baseline and stressed variants.
- Reuse seeds when comparing design alternatives.
- Prefer deterministic schedules for regression suites.
References
- Read
references/scenario-patterns.md for templates, built-in mappings, and anti-pattern guardrails.
- Use these repo sources:
canonical-catalogue/DSDS Canonical Catalogue - scenarios to ship.csvcanonical-catalogue/DSDS Canonical Catalogue - Failure modes & propagation semantics.csvcanonical-catalogue/DSDS Canonical Catalogue - Patterns for scenario generation.csvplanning/IMPLEMENTATION_PLAN.md (Phase 7)
