[PM-19590] Add k6 load testing script for SyncController's /sync endpoint (#5508)

* Add k6 load testing script for sync endpoint

* Refactor sync response validation to use lowercase keys

* Remove access token validation from sync.js

* Update http_req_duration threshold in sync.js from 400ms to 1200ms

Author: r-tome

perf/load/sync.js

@@ -0,0 +1,90 @@
+import http from "k6/http";
+import { check, fail } from "k6";
+import { authenticate } from "./helpers/auth.js";
+
+const IDENTITY_URL = __ENV.IDENTITY_URL;
+const API_URL = __ENV.API_URL;
+const CLIENT_ID = __ENV.CLIENT_ID;
+const AUTH_USERNAME = __ENV.AUTH_USER_EMAIL;
+const AUTH_PASSWORD = __ENV.AUTH_USER_PASSWORD_HASH;
+
+export const options = {
+  ext: {
+    loadimpact: {
+      projectID: 3639465,
+      name: "Sync",
+    },
+  },
+  scenarios: {
+    constant_load: {
+      executor: "constant-arrival-rate",
+      rate: 30,
+      timeUnit: "1m", // 0.5 requests / second
+      duration: "10m",
+      preAllocatedVUs: 5,
+    },
+    ramping_load: {
+      executor: "ramping-arrival-rate",
+      startRate: 30,
+      timeUnit: "1m", // 0.5 requests / second to start
+      stages: [
+        { duration: "30s", target: 30 },
+        { duration: "2m", target: 75 },
+        { duration: "1m", target: 60 },
+        { duration: "2m", target: 100 },
+        { duration: "2m", target: 90 },
+        { duration: "1m", target: 120 },
+        { duration: "30s", target: 150 },
+        { duration: "30s", target: 60 },
+        { duration: "30s", target: 0 },
+      ],
+      preAllocatedVUs: 20,
+    },
+  },
+  thresholds: {
+    http_req_failed: ["rate<0.01"],
+    http_req_duration: ["p(95)<1200"],
+  },
+};
+
+export function setup() {
+  return authenticate(IDENTITY_URL, CLIENT_ID, AUTH_USERNAME, AUTH_PASSWORD);
+}
+
+export default function (data) {
+  const params = {
+    headers: {
+      Accept: "application/json",
+      "Content-Type": "application/json",
+      Authorization: `Bearer ${data.access_token}`,
+      "X-ClientId": CLIENT_ID,
+    },
+    tags: { name: "Sync" },
+  };
+
+  const excludeDomains = Math.random() > 0.5;
+  
+  const syncRes = http.get(`${API_URL}/sync?excludeDomains=${excludeDomains}`, params);
+  if (
+    !check(syncRes, {
+      "sync status is 200": (r) => r.status === 200,
+    })
+  ) {
+    console.error(`Sync failed with status ${syncRes.status}: ${syncRes.body}`);
+    fail("sync status code was *not* 200");
+  }
+
+  if (syncRes.status === 200) {
+    const syncJson = syncRes.json();
+
+    check(syncJson, {
+      "sync response has profile": (j) => j.profile !== undefined,
+      "sync response has folders": (j) => Array.isArray(j.folders),
+      "sync response has collections": (j) => Array.isArray(j.collections),
+      "sync response has ciphers": (j) => Array.isArray(j.ciphers),
+      "sync response has policies": (j) => Array.isArray(j.policies),
+      "sync response has sends": (j) => Array.isArray(j.sends),
+      "sync response has correct object type": (j) => j.object === "sync"
+    });
+  }
+}