Merge pull request #6807 from matrix-org/pseudonymous-analytics-id

Replace Posthog user hash-based tracking with a UUID stored in account_data

src/Lifecycle.ts

@@ -574,11 +574,12 @@ async function doSetLoggedIn(
         await abortLogin();
     }
 
-    PosthogAnalytics.instance.updateAnonymityFromSettings(credentials.userId);
-
     Analytics.setLoggedIn(credentials.guest, credentials.homeserverUrl);
 
     MatrixClientPeg.replaceUsingCreds(credentials);
+
+    PosthogAnalytics.instance.updateAnonymityFromSettings(credentials.userId);
+
     const client = MatrixClientPeg.get();
 
     if (credentials.freshLogin && SettingsStore.getValue("feature_dehydration")) {

src/PosthogAnalytics.ts

@@ -18,6 +18,8 @@ import posthog, { PostHog } from 'posthog-js';
 import PlatformPeg from './PlatformPeg';
 import SdkConfig from './SdkConfig';
 import SettingsStore from './settings/SettingsStore';
+import { MatrixClientPeg } from "./MatrixClientPeg";
+import { MatrixClient } from "matrix-js-sdk/src/client";
 
 /* Posthog analytics tracking.
  *
@@ -141,6 +143,7 @@ export class PosthogAnalytics {
     private enabled = false;
     private static _instance = null;
     private platformSuperProperties = {};
+    private static ANALYTICS_ID_EVENT_TYPE = "im.vector.web.analytics_id";
 
     public static get instance(): PosthogAnalytics {
         if (!this._instance) {
@@ -274,9 +277,32 @@ export class PosthogAnalytics {
         this.anonymity = anonymity;
     }
 
-    public async identifyUser(userId: string): Promise<void> {
+    private static getRandomAnalyticsId(): string {
+        return [...crypto.getRandomValues(new Uint8Array(16))].map((c) => c.toString(16)).join('');
+    }
+
+    public async identifyUser(client: MatrixClient, analyticsIdGenerator: () => string): Promise<void> {
         if (this.anonymity == Anonymity.Pseudonymous) {
-            this.posthog.identify(await hashHex(userId));
+            // Check the user's account_data for an analytics ID to use. Storing the ID in account_data allows
+            // different devices to send the same ID.
+            try {
+                const accountData = await client.getAccountDataFromServer(PosthogAnalytics.ANALYTICS_ID_EVENT_TYPE);
+                let analyticsID = accountData?.id;
+                if (!analyticsID) {
+                    // Couldn't retrieve an analytics ID from user settings, so create one and set it on the server.
+                    // Note there's a race condition here - if two devices do these steps at the same time, last write
+                    // wins, and the first writer will send tracking with an ID that doesn't match the one on the server
+                    // until the next time account data is refreshed and this function is called (most likely on next
+                    // page load). This will happen pretty infrequently, so we can tolerate the possibility.
+                    analyticsID = analyticsIdGenerator();
+                    await client.setAccountData("im.vector.web.analytics_id", { id: analyticsID });
+                }
+                this.posthog.identify(analyticsID);
+            } catch (e) {
+                // The above could fail due to network requests, but not essential to starting the application,
+                // so swallow it.
+                console.log("Unable to identify user for tracking" + e.toString());
+            }
         }
     }
 
@@ -349,7 +375,7 @@ export class PosthogAnalytics {
         // Identify the user (via hashed user ID) to posthog if anonymity is pseudonmyous
         this.setAnonymity(PosthogAnalytics.getAnonymityFromSettings());
         if (userId && this.getAnonymity() == Anonymity.Pseudonymous) {
-            await this.identifyUser(userId);
+            await this.identifyUser(MatrixClientPeg.get(), PosthogAnalytics.getRandomAnalyticsId);
         }
     }
 }

test/PosthogAnalytics-test.ts

@@ -218,15 +218,28 @@ bd75b3e080945674c0351f75e0db33d1e90986fa07b318ea7edf776f5eef38d4`);
 
         it("Should identify the user to posthog if pseudonymous", async () => {
             analytics.setAnonymity(Anonymity.Pseudonymous);
-            await analytics.identifyUser("foo");
-            expect(fakePosthog.identify.mock.calls[0][0])
-                .toBe("2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae");
+            class FakeClient {
+                getAccountDataFromServer = jest.fn().mockResolvedValue(null);
+                setAccountData = jest.fn().mockResolvedValue({});
+            }
+            await analytics.identifyUser(new FakeClient(), () => "analytics_id" );
+            expect(fakePosthog.identify.mock.calls[0][0]).toBe("analytics_id");
         });
 
         it("Should not identify the user to posthog if anonymous", async () => {
             analytics.setAnonymity(Anonymity.Anonymous);
-            await analytics.identifyUser("foo");
+            await analytics.identifyUser(null);
             expect(fakePosthog.identify.mock.calls.length).toBe(0);
         });
+
+        it("Should identify using the server's analytics id if present", async () => {
+            analytics.setAnonymity(Anonymity.Pseudonymous);
+            class FakeClient {
+                getAccountDataFromServer = jest.fn().mockResolvedValue({ id: "existing_analytics_id" });
+                setAccountData = jest.fn().mockResolvedValue({});
+            }
+            await analytics.identifyUser(new FakeClient(), () => "new_analytics_id" );
+            expect(fakePosthog.identify.mock.calls[0][0]).toBe("existing_analytics_id");
+        });
     });
 });