feat: Use GOOGLE_APPLICATION_CREDENTIALS if json value (#32)

* Check GOOGLE_APPLICATION_CREDENTIALS env-var in fromApplicationDefaultCredentials * tiny fix * check if decoded env-var is Map type * add test for :fromApplicationDefaultCredentials * add test for invalid service account json * remove platform dependency * Apply suggestions from code review * hide envSymbol --------- Co-authored-by: Remi Rousselet <darky12s@gmail.com>
invertase · May 6, 2024 · 5003b77 · 5003b77
1 parent 98cf2d1
commit 5003b77
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diff --git a/packages/dart_firebase_admin/lib/dart_firebase_admin.dart b/packages/dart_firebase_admin/lib/dart_firebase_admin.dart
@@ -1 +1 @@
-export 'src/app.dart';
+export 'src/app.dart' hide envSymbol;
diff --git a/packages/dart_firebase_admin/lib/src/app/credential.dart b/packages/dart_firebase_admin/lib/src/app/credential.dart
@@ -1,5 +1,8 @@
 part of '../app.dart';
 
+@internal
+const envSymbol = #_envSymbol;
+
 /// Authentication information for Firebase Admin SDK.
 class Credential {
   Credential._(
@@ -41,11 +44,28 @@ class Credential {
   }
 
   /// Log in to firebase using the environment variable.
-  Credential.fromApplicationDefaultCredentials({String? serviceAccountId})
-      : this._(
-          null,
-          serviceAccountId: serviceAccountId,
-        );
+  factory Credential.fromApplicationDefaultCredentials({
+    String? serviceAccountId,
+  }) {
+    ServiceAccountCredentials? creds;
+
+    final env =
+        Zone.current[envSymbol] as Map<String, String>? ?? Platform.environment;
+    final maybeConfig = env['GOOGLE_APPLICATION_CREDENTIALS'];
+    if (maybeConfig != null) {
+      try {
+        final decodedValue = jsonDecode(maybeConfig);
+        if (decodedValue is Map) {
+          creds = ServiceAccountCredentials.fromJson(decodedValue);
+        }
+      } on FormatException catch (_) {}
+    }
+
+    return Credential._(
+      creds,
+      serviceAccountId: serviceAccountId,
+    );
+  }
 
   @internal
   final String? serviceAccountId;

diff --git a/packages/dart_firebase_admin/test/credential_test.dart b/packages/dart_firebase_admin/test/credential_test.dart
@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ -66,5 +67,45 @@ void main() {
         Credential.fromServiceAccount(fs.file('service-account.json'));
       });
     });
+
+    group('fromApplicationDefaultCredentials', () {
+      test(
+          'completes if `GOOGLE_APPLICATION_CREDENTIALS` environment-variable is valid service account JSON',
+          () {
+        final fakeServiceAccount = {
+          'GOOGLE_APPLICATION_CREDENTIALS': '''
+{
+  "type": "service_account",
+  "client_id": "id",
+  "private_key": ${jsonEncode(_fakeRSAKey)},
+  "client_email": "foo@bar.com"
+}
+''',
+        };
+        final credential = runZoned(
+          Credential.fromApplicationDefaultCredentials,
+          zoneValues: {envSymbol: fakeServiceAccount},
+        );
+        expect(credential.serviceAccountCredentials, isNotNull);
+
+        // Verify if service account is actually being used
+        expect(
+          credential.serviceAccountCredentials!.email,
+          'foo@bar.com',
+        );
+      });
+
+      test(
+          'does nothing if `GOOGLE_APPLICATION_CREDENTIALS` environment-variable is not valid service account JSON',
+          () {
+        final credential = runZoned(
+          Credential.fromApplicationDefaultCredentials,
+          zoneValues: {
+            envSymbol: {'GOOGLE_APPLICATION_CREDENTIALS': ''},
+          },
+        );
+        expect(credential.serviceAccountCredentials, isNull);
+      });
+    });
   });
 }