k6 step-load rig: staircase scenarios, per-step/per-endpoint tagging, live Prometheus remote-write, Grafana dashboard

manifests/loadtest/k6-step-script.yaml

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+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: k6-step-script
+  namespace: loadtest
+data:
+  step.js: |
+    // Step-load (staircase) test. Hits a collection of endpoints, stepping
+    // the request rate up over time, tagging every request with its step and
+    // endpoint so latency can be sliced either way in Grafana.
+    //
+    // Env:
+    //   BASE_URL        - target base URL
+    //   ENDPOINTS_JSON  - [{"name":"list","method":"GET","path":"/x","weight":2}, ...]
+    //   START_RPS       - rate of step 1
+    //   STEP_RPS        - rate added each step
+    //   STEP_DURATION   - hold time per step, e.g. "2m"
+    //   STEPS           - number of steps
+    import http from 'k6/http';
+    import { check } from 'k6';
+    import exec from 'k6/execution';
+
+    const BASE = __ENV.BASE_URL;
+    let endpoints;
+    try {
+      endpoints = JSON.parse(__ENV.ENDPOINTS_JSON);
+    } catch (e) {
+      throw new Error('ENDPOINTS_JSON is not valid JSON: ' + e.message);
+    }
+    // expand weights
+    const pool = [];
+    for (const ep of endpoints) {
+      for (let i = 0; i < (ep.weight || 1); i++) pool.push(ep);
+    }
+
+    const startRps = parseInt(__ENV.START_RPS || '50');
+    const stepRps = parseInt(__ENV.STEP_RPS || '50');
+    const stepDurMs = ms(__ENV.STEP_DURATION || '2m');
+    const steps = parseInt(__ENV.STEPS || '5');
+    const rampMs = 5000;
+
+    // Build stage list and per-step [startMs, endMs, label] windows.
+    // Each step: 5s quick ramp to the rate, then a hold.
+    const stages = [];
+    const windows = [];
+    let clock = 0;
+    for (let i = 0; i < steps; i++) {
+      const rate = startRps + i * stepRps;
+      stages.push({ duration: ms2str(rampMs), target: rate });
+      clock += rampMs;
+      const wStart = clock;
+      stages.push({ duration: ms2str(stepDurMs), target: rate });
+      clock += stepDurMs;
+      windows.push([wStart, clock, `step${i + 1} @ ${rate} rps`]);
+    }
+    const totalMs = clock;
+    const maxRate = startRps + (steps - 1) * stepRps;
+    const vus = Math.max(10, Math.ceil(maxRate * 2));
+
+    function ms(s) {
+      const m = /^(\d+)(ms|s|m)$/.exec(String(s));
+      if (!m) throw new Error('bad duration: ' + s);
+      return +m[1] * ({ ms: 1, s: 1000, m: 60000 })[m[2]];
+    }
+    function ms2str(n) { return n + 'ms'; }
+
+    export const options = {
+      discardResponseBodies: true,
+      scenarios: {
+        staircase: {
+          executor: 'ramping-arrival-rate',
+          startRate: 0,
+          preAllocatedVUs: vus,
+          maxVUs: vus,
+          stages: stages,
+        },
+      },
+      thresholds: { http_req_failed: ['rate<0.05'] },
+    };
+
+    export default function () {
+      const elapsed = exec.scenario.progress * totalMs;
+      let step = 'ramp-up';
+      for (const [s, e, label] of windows) {
+        if (elapsed >= s && elapsed < e) { step = label; break; }
+      }
+      const ep = pool[exec.scenario.iterationInTest % pool.length];
+      const url = BASE + ep.path;
+      const params = { tags: { name: ep.name, step: step }, timeout: '15s' };
+      const res = (ep.method || 'GET') === 'POST'
+        ? http.post(url, ep.body || '', params)
+        : http.get(url, params);
+      check(res, { ok: (r) => r.status < 300 });
+    }