feat: Support passing google.auth typed credentials in `initialize_…

…app()` (#821) * feat: Support passing `google.auth` typed credentials in `initialize_app()` * Refactor and add unit test

firebase_admin/__init__.py

@@ -18,6 +18,7 @@
 import os
 import threading
 
+from google.auth.credentials import Credentials as GoogleAuthCredentials
 from google.auth.exceptions import DefaultCredentialsError
 from firebase_admin import credentials
 from firebase_admin.__about__ import __version__
@@ -208,10 +209,13 @@ def __init__(self, name, credential, options):
  'non-empty string.'.format(name))
  self._name = name
 
- if not isinstance(credential, credentials.Base):
+ if isinstance(credential, GoogleAuthCredentials):
+ self._credential = credentials._ExternalCredentials(credential) # pylint: disable=protected-access
+ elif isinstance(credential, credentials.Base):
+ self._credential = credential
+ else:
  raise ValueError('Illegal Firebase credential provided. App must be initialized '
  'with a valid credential instance.')
- self._credential = credential
  self._options = _AppOptions(options)
  self._lock = threading.RLock()
  self._services = {}

firebase_admin/credentials.py

@@ -18,6 +18,7 @@
 import pathlib
 
 import google.auth
+from google.auth.credentials import Credentials as GoogleAuthCredentials
 from google.auth.transport import requests
 from google.oauth2 import credentials
 from google.oauth2 import service_account
@@ -58,6 +59,19 @@ def get_credential(self):
  """Returns the Google credential instance used for authentication."""
  raise NotImplementedError
 
+class _ExternalCredentials(Base):
+ """A wrapper for google.auth.credentials.Credentials typed credential instances"""
+
+ def __init__(self, credential: GoogleAuthCredentials):
+ super(_ExternalCredentials, self).__init__()
+ self._g_credential = credential
+
+ def get_credential(self):
+ """Returns the underlying Google Credential
+
+ Returns:
+ google.auth.credentials.Credentials: A Google Auth credential instance."""
+ return self._g_credential
 
 class Certificate(Base):
  """A credential initialized from a JSON certificate keyfile."""

tests/test_app.py

@@ -246,6 +246,16 @@ def test_non_default_app_init(self, app_credential):
  with pytest.raises(ValueError):
  firebase_admin.initialize_app(app_credential, name='myApp')
 
+ def test_app_init_with_google_auth_cred(self):
+ cred = testutils.MockGoogleCredential()
+ assert isinstance(cred, credentials.GoogleAuthCredentials)
+ app = firebase_admin.initialize_app(cred)
+ assert cred is app.credential.get_credential()
+ assert isinstance(app.credential, credentials.Base)
+ assert isinstance(app.credential, credentials._ExternalCredentials)
+ with pytest.raises(ValueError):
+ firebase_admin.initialize_app(app_credential)
+
  @pytest.mark.parametrize('cred', invalid_credentials)
  def test_app_init_with_invalid_credential(self, cred):
  with pytest.raises(ValueError):