Ensure that the the jwt service is called before starting a call

playwright/restricted-sfu.spec.ts

@@ -0,0 +1,75 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { expect, test } from "@playwright/test";
+import { sleep } from "matrix-js-sdk/lib/utils.js";
+
+test("Should request JWT token before starting the call", async ({ page }) => {
+  await page.goto("/");
+
+  let sfGetTimestamp = 0;
+  let sendStateEventTimestamp = 0;
+  await page.route(
+    "**/matrix-rtc.m.localhost/livekit/jwt/sfu/get",
+    async (route) => {
+      await sleep(2000); // Simulate very slow request
+      await route.continue();
+      sfGetTimestamp = Date.now();
+    },
+  );
+
+  await page.route(
+    "**/state/org.matrix.msc3401.call.member/**",
+    async (route) => {
+      await route.continue();
+      sendStateEventTimestamp = Date.now();
+    },
+  );
+
+  await page.getByTestId("home_callName").click();
+  await page.getByTestId("home_callName").fill("HelloCall");
+  await page.getByTestId("home_displayName").click();
+  await page.getByTestId("home_displayName").fill("John Doe");
+  await page.getByTestId("home_go").click();
+
+  // Join the call
+  await page.getByTestId("lobby_joinCall").click();
+  await page.waitForTimeout(4000);
+  // Ensure that the call is connected
+  await page
+    .locator("div")
+    .filter({ hasText: /^HelloCall$/ })
+    .click();
+
+  expect(sfGetTimestamp).toBeGreaterThan(0);
+  expect(sendStateEventTimestamp).toBeGreaterThan(0);
+  expect(sfGetTimestamp).toBeLessThan(sendStateEventTimestamp);
+});
+
+test("Error when pre-warming the focus are caught by the ErrorBoundary", async ({
+  page,
+}) => {
+  await page.goto("/");
+
+  await page.route("**/openid/request_token", async (route) => {
+    await route.fulfill({
+      status: 418, // Simulate an error not retryable
+    });
+  });
+
+  await page.getByTestId("home_callName").click();
+  await page.getByTestId("home_callName").fill("HelloCall");
+  await page.getByTestId("home_displayName").click();
+  await page.getByTestId("home_displayName").fill("John Doe");
+  await page.getByTestId("home_go").click();
+
+  // Join the call
+  await page.getByTestId("lobby_joinCall").click();
+
+  // Should fail
+  await expect(page.getByText("Something went wrong")).toBeVisible();
+});

playwright/sfu-reconnect-bug.spec.ts

@@ -100,5 +100,5 @@ test("When creator left, avoid reconnect to the same SFU", async ({
   // https://github.com/element-hq/element-call/issues/3344
   // The app used to request a new jwt token then to reconnect to the SFU
   expect(wsConnectionCount).toBe(1);
-  expect(sfuGetCallCount).toBe(1);
+  expect(sfuGetCallCount).toBe(2 /* the first one is for the warmup */);
 });

src/rtcSessionHelpers.ts

@@ -5,14 +5,14 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import { type MatrixRTCSession } from "matrix-js-sdk/lib/matrixrtc";
-import { logger } from "matrix-js-sdk/lib/logger";
 import {
   isLivekitFocus,
   isLivekitFocusConfig,
   type LivekitFocus,
   type LivekitFocusActive,
+  type MatrixRTCSession,
 } from "matrix-js-sdk/lib/matrixrtc";
+import { logger } from "matrix-js-sdk/lib/logger";
 import { AutoDiscovery } from "matrix-js-sdk/lib/autodiscovery";
 
 import { PosthogAnalytics } from "./analytics/PosthogAnalytics";
@@ -20,6 +20,7 @@ import { Config } from "./config/Config";
 import { ElementWidgetActions, widget, type WidgetHelpers } from "./widget";
 import { MatrixRTCFocusMissingError } from "./utils/errors";
 import { getUrlParams } from "./UrlParams";
+import { getSFUConfigWithOpenID } from "./livekit/openIDSFU.ts";
 
 const FOCI_WK_KEY = "org.matrix.msc4143.rtc_foci";
 
@@ -51,32 +52,13 @@ async function makePreferredLivekitFoci(
   if (domain) {
     // we use AutoDiscovery instead of relying on the MatrixClient having already
     // been fully configured and started
-    const wellKnownFoci = (await AutoDiscovery.getRawClientConfig(domain))?.[
-      FOCI_WK_KEY
-    ];
-    if (Array.isArray(wellKnownFoci)) {
-      preferredFoci.push(
-        ...wellKnownFoci
-          .filter((f) => !!f)
-          .filter(isLivekitFocusConfig)
-          .map((wellKnownFocus) => {
-            logger.log(
-              "Adding livekit focus from well known: ",
-              wellKnownFocus,
-            );
-            return { ...wellKnownFocus, livekit_alias: livekitAlias };
-          }),
-      );
-    }
+    const wellKnownFoci = await getFocusListFromWellKnown(domain, livekitAlias);
+    logger.log("Adding livekit focus from well known: ", wellKnownFoci);
+    preferredFoci.push(...wellKnownFoci);
   }
 
-  const urlFromConf = Config.get().livekit?.livekit_service_url;
-  if (urlFromConf) {
-    const focusFormConf: LivekitFocus = {
-      type: "livekit",
-      livekit_service_url: urlFromConf,
-      livekit_alias: livekitAlias,
-    };
+  const focusFormConf = getFocusListFromConfig(livekitAlias);
+  if (focusFormConf) {
     logger.log("Adding livekit focus from config: ", focusFormConf);
     preferredFoci.push(focusFormConf);
   }
@@ -94,6 +76,93 @@ async function makePreferredLivekitFoci(
   // if (focusOtherMembers) preferredFoci.push(focusOtherMembers);
 }
 
+async function getFocusListFromWellKnown(
+  domain: string,
+  alias: string,
+): Promise<LivekitFocus[]> {
+  if (domain) {
+    // we use AutoDiscovery instead of relying on the MatrixClient having already
+    // been fully configured and started
+    const wellKnownFoci = (await AutoDiscovery.getRawClientConfig(domain))?.[
+      FOCI_WK_KEY
+    ];
+    if (Array.isArray(wellKnownFoci)) {
+      return wellKnownFoci
+        .filter((f) => !!f)
+        .filter(isLivekitFocusConfig)
+        .map((wellKnownFocus) => {
+          return { ...wellKnownFocus, livekit_alias: alias };
+        });
+    }
+  }
+  return [];
+}
+
+function getFocusListFromConfig(livekitAlias: string): LivekitFocus | null {
+  const urlFromConf = Config.get().livekit?.livekit_service_url;
+  if (urlFromConf) {
+    return {
+      type: "livekit",
+      livekit_service_url: urlFromConf,
+      livekit_alias: livekitAlias,
+    };
+  }
+  return null;
+}
+
+export async function getMyPreferredLivekitFoci(
+  domain: string | null,
+  livekitAlias: string,
+): Promise<LivekitFocus> {
+  if (domain) {
+    // we use AutoDiscovery instead of relying on the MatrixClient having already
+    // been fully configured and started
+    const wellKnownFociList = await getFocusListFromWellKnown(
+      domain,
+      livekitAlias,
+    );
+    if (wellKnownFociList.length > 0) {
+      return wellKnownFociList[0];
+    }
+  }
+
+  const urlFromConf = Config.get().livekit?.livekit_service_url;
+  if (urlFromConf) {
+    return {
+      type: "livekit",
+      livekit_service_url: urlFromConf,
+      livekit_alias: livekitAlias,
+    };
+  }
+  throw new MatrixRTCFocusMissingError(domain ?? "");
+}
+
+// Stop-gap solution for pre-warming the SFU.
+// This is needed to ensure that the livekit room is created before we try to join the rtc session.
+// This is because the livekit room creation is done by the auth service and this can be restricted to
+// only specific users, so we need to ensure that the room is created before we try to join it.
+async function preWarmSFU(rtcSession: MatrixRTCSession, livekitAlias: string) {
+  const client = rtcSession.room.client;
+  // We need to make sure that the livekit room is created before sending the membership event
+  // because other joiners might not be able to join the call if the room does not exist yet.
+  const fociToWarmup = await getMyPreferredLivekitFoci(
+    client.getDomain(),
+    livekitAlias
+  );
+
+  // Request a token in advance to warm up the livekit room.
+  // Let it throw if it fails, errors will be handled by the ErrorBoundary, if it fails now
+  // it will fail later when we try to join the room.
+  await getSFUConfigWithOpenID(client, fociToWarmup);
+  // For now we don't do anything with the token returned by `getSFUConfigWithOpenID`, it is just to ensure that we
+  // call the `sfu/get` endpoint so that the auth service create the room in advance if it can.
+  // Note: This is not actually checking that the room was created! If the roon creation is
+  // not done by the auth service, the call will fail later when we try to join the room; that case
+  // is a miss-configuration of the auth service, you should be able to create room in your selected SFU.
+  // A solution could be to call the internal `/validate` endpoint to check that the room exists, but this needs
+  // to access livekit internal APIs, so we don't do it for now.
+}
+
 export async function enterRTCSession(
   rtcSession: MatrixRTCSession,
   encryptMedia: boolean,
@@ -112,6 +181,10 @@ export async function enterRTCSession(
   const { features, matrix_rtc_session: matrixRtcSessionConfig } = Config.get();
   const useDeviceSessionMemberEvents =
     features?.feature_use_device_session_member_events;
+
+  // Pre-warm the SFU to ensure that the room is created before anyone tries to join it.
+  await preWarmSFU(rtcSession, livekitAlias);
+
   rtcSession.joinRoomSession(
     await makePreferredLivekitFoci(rtcSession, livekitAlias),
     makeActiveFocus(),