perf: add k6 ramp-and-hold spike scenario (Closes #457)

.github/workflows/k6-spike-test.yml

@@ -0,0 +1,32 @@
+name: k6 Spike Test
+
+on:
+  workflow_dispatch:
+  pull_request:
+    paths:
+      - 'tests/k6/**'
+      - '.github/workflows/k6-spike-test.yml'
+
+jobs:
+  spike:
+    name: Plans read-path spike (10 -> 2000 VUs)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run k6 spike profile
+        uses: grafana/k6-action@v0.3.1
+        with:
+          filename: tests/k6/plans-spike.js
+          flags: --summary-export=results/k6-spike-summary.json
+        env:
+          BASE_URL: ${{ secrets.STAGING_URL }}
+          API_KEY: ${{ secrets.STAGING_API_KEY }}
+
+      - name: Publish JSON summary artifact
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: k6-spike-summary
+          path: results/k6-spike-summary.json
+          if-no-files-found: warn

tests/k6/plans-spike.js

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+import http from 'k6/http';
+import { check, sleep, group } from 'k6';
+import { Counter, Trend } from 'k6/metrics';
+
+const planErrors = new Counter('plan_errors');
+const planLatency = new Trend('plan_latency');
+const planP99 = new Trend('plan_p99_latency');
+
+const BASE_URL = __ENV.BASE_URL || 'http://localhost:8080';
+const API_KEY = __ENV.API_KEY || 'test-key';
+const PLANS_PATH = __ENV.PLANS_PATH || '/api/v1/plans';
+
+export const options = {
+  vus: 10,
+  stages: [
+    { duration: '5m', target: 2000 },
+    { duration: '2m', target: 2000 },
+    { duration: '1m', target: 0 },
+  ],
+  thresholds: {
+    http_req_failed: ['rate<0.01'],
+    http_req_duration: ['p(99)<1500'],
+    plan_p99_latency: ['p(99)<1500'],
+    plan_errors: ['count<1'],
+  },
+};
+
+export default function () {
+  group('Plans Read - Spike', () => {
+    const params = {
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${API_KEY}`,
+      },
+    };
+
+    const res = http.get(`${BASE_URL}${PLANS_PATH}`, params);
+
+    const ok = check(res, {
+      'status is 200': (r) => r.status === 200,
+      'p99 < 1500ms': (r) => r.timings.duration < 1500,
+      'body is not empty': (r) => r.body && r.body.length > 0,
+    });
+
+    if (!ok) planErrors.add(1);
+    planLatency.add(res.timings.duration);
+    planP99.add(res.timings.duration);
+
+    sleep(1);
+  });
+}