k6ParseToHDRHistogram.ts

  private async _runK6(metadata: RunK6Metadata, config: K6Options) {
    const { queryName, outputFile } = metadata

    // If "debug" true, log all HTTP responses
    if (this.config.debug) config.httpDebug = 'full'

    // Write the K6 configuration JSON to a temp file, to pass as CLI flag
    const tmpConfig = path.join(__dirname, 'tmp', `${queryName}_config.json`)
    await fs.outputJSON(tmpConfig, config)

    // outPath is where the JSON report stats will go, scriptFile points K6 to the JS script for the load test
    const outPath = path.join(this.reportPath, outputFile)
    const scriptFile = path.join(__dirname, 'k6', 'loadScript.js')

    // Make sure the directory exists, or K6 will fail when writing
    await fs.ensureFile(outPath)

    // Invoke 'k6 run <scriptFile path> --config <tmpConfig path> --summary-export <outPath>'
    const baseOpts: string[] = []
    baseOpts.push('run', scriptFile)
    baseOpts.push('--config', tmpConfig)
    baseOpts.push('--out', 'json=k6_raw_stats.json')
    baseOpts.push('--summary-export', outPath)

    const k6 = cp.spawnSync(this.k6BinaryPath, baseOpts, {
      cwd: __dirname,
      stdio: 'inherit',
    })

    if (k6.error) console.log('ERROR RUNNING K6:', k6.error)

    // Create a line-reader to parse each entry of JSONL logs
    const fileStream = fs.createReadStream('k6_raw_stats.json')
    const rl = readline.createInterface({
      input: fileStream,
      crlfDelay: Infinity,
    })

    const histogram = hdr.build()
    let stats: K6Point[] = []

    for await (const line of rl) {
      const stat: K6Metric | K6Point = JSON.parse(line)
      if (stat.type != 'Point') continue
      if (stat.metric != 'http_req_duration') continue
      if (Number(stat.data.tags.status) < 200) continue
      stats.push(stat)
      histogram.recordValue(stat.data.value)
    }

    fs.writeJSONSync('k6_parsed_stats.json', stats)

    console.log(histogram.summary)
    console.log(histogram.outputPercentileDistribution())

    // Remove the temp config file with the K6 run parameters
    await fs.remove(tmpConfig)
    // Return the JSON output stats produced by K6 for bench
    const jsonStats = fs.readJSONSync(outPath)
    return jsonStats
  }
}