Bug 1845362 - SSR support for Glean.js

.dictionary

@@ -78,3 +78,4 @@ webpack
 async
 queueing
 LocalStorage
+ssr

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 [Full changelog](https://github.com/mozilla/glean.js/compare/v1.4.0...main)
 
+* [#1733](https://github.com/mozilla/glean.js/pull/1733): Add SSR support for Glean.js
 * [#1728](https://github.com/mozilla/glean.js/pull/1728): Migrate client_id and first_run_date.
 * [#1695](https://github.com/mozilla/glean.js/pull/1695): Update Glean.js web to use LocalStorage.
 

glean/src/core/internal_metrics/sync.ts

@@ -11,7 +11,7 @@ import { InternalDatetimeMetricType as DatetimeMetricType } from "../metrics/typ
 import { InternalStringMetricType as StringMetricType } from "../metrics/types/string.js";
 import { createMetric } from "../metrics/utils.js";
 import TimeUnit from "../metrics/time_unit.js";
-import { generateUUIDv4 } from "../utils.js";
+import { generateUUIDv4, isWindowObjectUnavailable } from "../utils.js";
 import { Lifetime } from "../metrics/lifetime.js";
 import log, { LoggingLevel } from "../log.js";
 import { Context } from "../context.js";
@@ -126,6 +126,13 @@ export class CoreMetricsSync {
   }
 
   initialize(): void {
+    // The "sync" version of Glean.js is only meant to be used in the browser.
+    // If we cannot access the window object, then we are unable to store
+    // any of the metric data in `localStorage`.
+    if (isWindowObjectUnavailable()) {
+      return;
+    }
+
     // If the client had used previous versions of Glean.js before we moved
     // to LocalStorage as the data store, then we need to move important
     // user data from IndexedDB to LocalStorage.

glean/src/core/utils.ts

@@ -311,3 +311,15 @@ export function getCurrentTimeInNanoSeconds(): number {
   }
   return now;
 }
+
+/**
+ * Checks if the current environment has access to the `window` object. This
+ * check is used to conditional-ize browser code for SSR projects. If the
+ * platform does not have access to the `window` APIs, then we are unable to
+ * store data in the browser.
+ *
+ * @returns Whether or not the current platform has access to the `window` object.
+ */
+export function isWindowObjectUnavailable(): boolean {
+  return typeof window === "undefined";
+}

glean/src/platform/browser/web/platform_info.ts

@@ -7,7 +7,12 @@ import { KnownOperatingSystems } from "../../../core/platform_info/shared.js";
 
 const BrowserPlatformInfo: PlatformInfoSync = {
   os(): KnownOperatingSystems {
-    const ua = navigator.userAgent;
+    let ua;
+    if (!!navigator && !!navigator.userAgent) {
+      ua = navigator.userAgent;
+    } else {
+      ua = KnownOperatingSystems.Unknown;
+    }
 
     if (ua.includes("Windows")) {
       return KnownOperatingSystems.Windows;

glean/src/platform/browser/web/storage.ts

@@ -12,9 +12,11 @@ import {
   getValueFromNestedObject,
   updateNestedObject
 } from "../../../core/storage/utils.js";
+import { isWindowObjectUnavailable } from "../../../core/utils.js";
 
 const LOG_TAG = "platform.web.Storage";
 
+// If `window.localStorage` is unavailable, we return undefined for all.
 class WebStore implements SynchronousStore {
   private logTag: string;
 
@@ -23,6 +25,10 @@ class WebStore implements SynchronousStore {
   }
 
   get(index: StorageIndex = []): JSONValue | undefined {
+    if (isWindowObjectUnavailable()) {
+      return;
+    }
+
     let result;
 
     try {
@@ -42,6 +48,10 @@ class WebStore implements SynchronousStore {
   }
 
   update(index: StorageIndex, transformFn: (v?: JSONValue) => JSONValue): void {
+    if (isWindowObjectUnavailable()) {
+      return;
+    }
+
     try {
       const json = localStorage.getItem(this.rootKey) || "{}";
       const obj = JSON.parse(json) as JSONObject;
@@ -54,6 +64,10 @@ class WebStore implements SynchronousStore {
   }
 
   delete(index: StorageIndex): void {
+    if (isWindowObjectUnavailable()) {
+      return;
+    }
+
     try {
       const json = localStorage.getItem(this.rootKey) || "{}";
       const obj = JSON.parse(json) as JSONObject;