aded k6 and script and updated code with better logic and indexing on schema

k6/booking-race.js

@@ -0,0 +1,49 @@
+import http from 'k6/http';
+import { check } from 'k6';
+import { Counter } from 'k6/metrics';
+
+const seed = JSON.parse(open('./seed-data.json'));
+const BASE_URL = __ENV.BASE_URL || 'http://app:3000';
+
+const successfulBookings = new Counter('successful_bookings');
+
+export const options = {
+  scenarios: {
+    concurrent_booking: {
+      executor: 'per-vu-iterations',
+      vus: 10,
+      iterations: 1,
+      maxDuration: '30s',
+    },
+  },
+  thresholds: {
+    successful_bookings: ['count==1'],
+  },
+};
+
+export default function () {
+  const session = seed.sessions[0];
+  const user = seed.users[__VU - 1];
+
+  const response = http.post(
+    `${BASE_URL}/sessions/${session.id}/book`,
+    JSON.stringify({ userId: user.id }),
+    {
+      headers: { 'Content-Type': 'application/json' },
+      responseCallback: http.expectedStatuses(200, 400),
+    }
+  );
+
+  if (response.status === 200) {
+    successfulBookings.add(1);
+  }
+
+  check(response, {
+    'booking returned expected status': (r) =>
+      r.status === 200 || r.status === 400,
+  });
+
+  console.log(
+    `VU ${__VU}: status=${response.status}, session=${session.id}`
+  );
+}