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deterministic load engine

K6-like load testing engine/CLI written in Rust.

Pipeline: Generate scenario → Setup → Validate → Run
Includes dry-run (plan preview / deterministic sampling) and mock run (no network) for fast testing.

Status: MVP / work in progress. The core architecture is the focus.

Key ideas

• Tick-based scheduler: workload stages (duration_sec + rps) → stream of ticks
• VU runtime executing journeys/steps
• Deterministic planning (seed) for reproducible runs
• JSON schema + scenario validation

Workspace layout

• bin/rload — CLI binary
• crates/libprotocol — scenario schema + parsing/validation
• crates/libruntime — scheduler, VU runtime, metrics, run engine
• crates/libcli — CLI helpers / UI (WIP)
• crates/test_support — test utils / fixtures helpers

Installation

Build from source

cargo build --release
./target/release/rload --help

Installation

Build from source:

cargo build --release

Run help:

./target/release/rload --help

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Usage

Run a scenario (real run):

./target/release/rload run --scenario examples/api-gw.json

Run mock (no network):

./target/release/rload run-mock --scenario examples/demo-scenario.json

Dry-run (plan preview / deterministic):

./target/release/rload dry-run --scenario examples/demo-scenario.json --iterations 1000

Useful dry-run options: --seed (default: 1000) --print-plan --limit-steps --output json --is-simulated

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Scenario validation

Validate scenario:

./target/release/rload validate --scenario examples/demo-scenario.json

Export JSON schema:

./target/release/rload schema --path docs/schema.json --version 1

Generate scenario template:

./target/release/rload generate --path examples/generated.json --version 1

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Report (JSON example)

After run or run-mock, the engine produces a structured JSON report.

Example:

{
  "scenario": {
    "name": "default_scenario",
    "version": "1"
  },
  "run": {
    "total_ticks": 1000,
    "duration_sec_planned": 10
  },
  "rps": {
    "planned_avg": 100,
    "achieved_avg": 111
  },
  "requests": {
    "total": 1000,
    "ok": 1000,
    "error": 0
  },
  "latency_overall_summary": {
    "count": 1000,
    "p50": 0,
    "p95": 0,
    "p99": 0
  },
  "error_and_quality": {
    "http_error_rate": 0.0
  }
}

Full report includes:

• tick arrival stats
• per-stage metrics
• per-endpoint metrics
• per-journey stats
• latency percentiles
• VU behavior metrics
• time model metrics

Designed for:

• CI validation
• dashboards
• regression testing
• threshold evaluation (planned)

Roadmap

See ROADMAP.md

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License

MIT