k6

What it does

How to write it

k6 run [OPTIONS] SCRIPT.js

Main parts

Commands

run SCRIPT

Run a test.

new FILE

Make an example script.

inspect SCRIPT

Show the options of a script.

cloud SCRIPT

Run in Grafana Cloud.

Most used

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$ run as a normal user# run as root (or with sudo)

1. 1A first test: 10 users for 30 seconds

   $cat smoke.js
   import http from "k6/http";
   import { check, sleep } from "k6";
   export default function () {
     const res = http.get(`${__ENV.BASE_URL}/health`);
     check(res, { "status is 200": (r) => r.status === 200 });
     sleep(1);
   }
   $k6 run -u 10 -d 30s -e BASE_URL=https://staging.example.com smoke.js

2. 2Thresholds: fail the pipeline when slow

   $cat load.js
   export const options = {
     stages: [ { duration: "1m", target: 50 }, { duration: "3m", target: 50 }, { duration: "30s", target: 0 } ],
     thresholds: { http_req_duration: ["p(95)<300"], http_req_failed: ["rate<0.01"] },
   };
   $k6 run load.js

   If a threshold fails, k6 exits with code 99 and the CI job fails.

3. 3Ramp up from the command line

   $k6 run --stage 30s:20,2m:20,10s:0 smoke.js

4. 4A POST with JSON and a token

   $cat api.js
   import http from "k6/http";
   export default function () {
     http.post(`${__ENV.BASE_URL}/api/cart`, JSON.stringify({ sku: "BA-101" }),
       { headers: { "Content-Type": "application/json", Authorization: `Bearer ${__ENV.TOKEN}` } });
   }
   $k6 run -e BASE_URL=https://staging.example.com -e TOKEN="$TOKEN" api.js

5. 5Run in Docker (no install)

   $docker run --rm -i grafana/k6 run - < smoke.js

6. 6In GitHub Actions after a staging deploy

   $cat .github/workflows/perf.yml
   - uses: grafana/setup-k6-action@v1
   - run: k6 run -e BASE_URL=https://staging.example.com load.js

7. 7Save the results

   $k6 run --summary-export summary.json --out json=raw.json load.js

8. 8Send metrics to Prometheus (remote write)

   $K6_PROMETHEUS_RW_SERVER_URL=http://prometheus:9090/api/v1/write k6 run -o experimental-prometheus-rw load.js

9. 9Make an example script

   $k6 new script.js

10. 10Debug one request

    $k6 run -i 1 --http-debug=full smoke.js

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Exit codes