fix(core): handle optional OpenTelemetry imports in Metro (#11210)

.changeset/calm-otters-trace.md

@@ -0,0 +1,5 @@
+---
+"@better-auth/core": patch
+---
+
+Prevent bundlers such as Metro from failing when the optional OpenTelemetry API is not installed.

e2e/smoke/package.json

@@ -7,12 +7,15 @@
     "better-auth": "workspace:*"
   },
   "devDependencies": {
+    "@babel/core": "^7.29.7",
     "@better-auth-test/test-utils": "workspace:*",
     "@better-auth/cimd": "workspace:*",
     "@better-auth/core": "workspace:*",
     "@better-auth/oauth-provider": "workspace:*",
     "@better-auth/redis-storage": "workspace:*",
     "@better-auth/sso": "workspace:*",
+    "@expo/metro-config": "57.0.12",
+    "@types/babel__core": "^7.20.5",
     "better-auth": "workspace:*",
     "ioredis": "^5.11.1",
     "msw": "^2.14.6"

e2e/smoke/test/expo-metro.spec.ts

@@ -0,0 +1,55 @@
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import { createRequire } from "node:module";
+import { join } from "node:path";
+import { it } from "node:test";
+import { fileURLToPath } from "node:url";
+import { parseSync } from "@babel/core";
+
+type CollectDependencies =
+	typeof import("@expo/metro-config/build/transform-worker/collect-dependencies.js").default;
+
+const repositoryRoot = fileURLToPath(new URL("../../..", import.meta.url));
+const require = createRequire(import.meta.url);
+const { default: collectDependencies } =
+	require("@expo/metro-config/build/transform-worker/collect-dependencies.js") as {
+		default: CollectDependencies;
+	};
+
+/**
+ * @see https://github.com/better-auth/better-auth/issues/11197
+ */
+it("marks the OpenTelemetry import as optional for Metro", async () => {
+	const instrumentationPath = join(
+		repositoryRoot,
+		"packages/core/dist/instrumentation/api.mjs",
+	);
+	const source = await readFile(instrumentationPath, "utf8");
+	const ast = parseSync(source, { sourceType: "module" });
+
+	assert.ok(ast);
+
+	const { dependencies } = collectDependencies(ast, {
+		allowOptionalDependencies: true,
+		asyncRequireModulePath: "metro-runtime/src/modules/asyncRequire",
+		collectOnly: true,
+		dynamicRequires: "reject",
+		inlineableCalls: ["require"],
+		keepRequireNames: false,
+		unstable_allowRequireContext: false,
+		unstable_isESMImportAtSource: null,
+	});
+	const openTelemetryDependency = dependencies.find(
+		(dependency) => dependency.name === "@opentelemetry/api",
+	);
+
+	assert.ok(
+		openTelemetryDependency,
+		"Metro should discover the OpenTelemetry import",
+	);
+	assert.equal(
+		openTelemetryDependency.data.isOptional,
+		true,
+		"Metro should treat the OpenTelemetry import as optional",
+	);
+});

packages/core/src/instrumentation/api.ts

@@ -4,13 +4,17 @@ import { noopOpenTelemetryAPI } from "./noop";
 let openTelemetryAPIPromise: Promise<void> | undefined;
 let openTelemetryAPI: OpenTelemetryAPI | undefined;
 
+async function loadOpenTelemetryAPI(): Promise<void> {
+	try {
+		openTelemetryAPI = await import("@opentelemetry/api");
+	} catch {
+		// OpenTelemetry is an optional peer dependency.
+	}
+}
+
 export function getOpenTelemetryAPI(): OpenTelemetryAPI {
 	if (!openTelemetryAPIPromise) {
-		openTelemetryAPIPromise = import("@opentelemetry/api")
-			.then((mod) => {
-				openTelemetryAPI = mod;
-			})
-			.catch(() => /* ignore failures */ undefined);
+		openTelemetryAPIPromise = loadOpenTelemetryAPI();
 	}
 
 	return openTelemetryAPI ?? noopOpenTelemetryAPI;