---
title: "Design a spike profile | Grafana Labs"
description: "Build a k6 spike test script with sharp stage transitions that simulate a sudden traffic burst and include a recovery observation period."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

# Design a spike profile

In this milestone, you write the `spike.js` script that defines your spike profile: a short baseline, a sharp burst, a recovery window, and a ramp down to zero. The shape is controlled by a `stages` array that raises and lowers the number of virtual users (VUs) over time.

Size your baseline and spike VU counts from your [Establish a performance baseline with k6](/docs/learning-paths/establish-k6-baseline/) results: pick a baseline close to your system’s normal concurrent load, then a spike target several times higher to simulate a surge. This path uses 5 baseline VUs and a 100-VU spike (a 20x jump) against [QuickPizza](https://quickpizza.grafana.com); replace the URL and targets when you test your own approved non-production stack.

To design a spike profile, complete the following steps:

1. Create `spike.js` and add imports:
   
   JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy
   
   ```javascript
   import http from 'k6/http';
   import { check, sleep } from 'k6';
   import { randomIntBetween } from 'https://jslib.k6.io/k6-utils/1.4.0/index.js';
   ```
2. Define `stages` and `thresholds`:
   
   JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy
   
   ```javascript
   export const options = {
     stages: [
       // Baseline: establish steady-state metrics at 5 VUs
       { duration: '1m', target: 5 },
       { duration: '1m', target: 5 },
       // Spike: ramp to 100 VUs (20x) in 10 seconds
       { duration: '10s', target: 100 },
       { duration: '1m', target: 100 },
       // Recovery: drop back to baseline and observe for 3 minutes
       { duration: '10s', target: 5 },
       { duration: '3m', target: 5 },
       { duration: '30s', target: 0 },
     ],
     thresholds: {
       http_req_duration: ['p(95)<1500'],
       http_req_failed: ['rate<0.10'],
     },
   };
   ```
   
   Ten-second ramps create the abrupt spike shape. Thresholds are looser than in a baseline test so the run can finish under burst load. Use `http_req_failed` for pass/fail on HTTP errors; keep checks in the default function for summary visibility.
3. Add the default function with the same checks as your baseline test:
   
   JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy
   
   ```javascript
   export default function () {
     const res = http.get('https://quickpizza.grafana.com');
   
     check(res, {
       'status is 200': (r) => r.status === 200,
       'response body is not empty': (r) => r.body.length > 0,
     });
   
     // Randomize the sleep time to simulate real user traffic
     sleep(randomIntBetween(1, 3));
   }
   ```
4. Save `spike.js`. Combine the `options` block and default function in one file before you run the test in the next milestone.

In the next milestone, you run the spike test and interpret the results.