Final Lab: Blocking performance test in continuous integration

What you will learn in this TP

• Write a smoke test for CI
• Create the workflow
• Observe a blocked pull request

Introduction #

What you will learn in this section

• Write a smoke test for CI
• Create the workflow
• Observe a blocked pull request

Context. A performance regression reached production last month. From now on, no pull request may degrade latency beyond the SLO.

Prerequisites: GitHub account, test repository  ·  Estimated time: 40 min

Performance tested on every change.

Hands-on #

Guided steps, with their solutions.

1. 1. Prepare the repository

   Why? The test lives next to the code it protects.

   In a repository, create docker-compose.yml (httpbin on port 8080) and tests/perf/smoke.js (10 VUs, 30 s, thresholds p95 < 300 ms and failures < 1%) targeting http://localhost:8080/get.

2. 2. Write the workflow

   Why? The official actions install k6 and run the script; an unmet threshold fails the job.

   Create .github/workflows/perf.yml, triggered on pull requests.

3. 3. Open a healthy pull request

   Why? To check the nominal path.

   Push to a branch and open a pull request: the job should succeed.

4. 4. Simulate a regression

   Why? Proof that the safeguard works.

   Change the tested route to /delay/1 (simulating slower code), push and observe the result.

Difficulty level : ●●●○○ (3/5)