fix: get default bucket from FIREBASE_CONFIG env if available

Author: Salakar

src/firebase_functions/options.py

@@ -331,9 +331,18 @@ def _endpoint(
         **kwargs,
     ) -> _manifest.ManifestEndpoint:
         assert kwargs["event_type"] is not None
-        # TODO get bucket from admin sdk if no bucket set
+        bucket = self.bucket
+        if bucket is None:
+            firebase_config = _util.firebase_config()
+            if firebase_config is not None:
+                bucket = firebase_config.storage_bucket
+        if bucket is None:
+            raise ValueError(
+                "Missing bucket name. If you are unit testing, please specify a bucket name"
+                " by providing a bucket name directly to the event handler or by setting the"
+                " FIREBASE_CONFIG environment variable.")
         event_filters: _typing.Any = {
-            "bucket": self.bucket,
+            "bucket": bucket,
         }
         event_trigger = _manifest.EventTrigger(
             eventType=kwargs["event_type"],

src/firebase_functions/private/util.py

@@ -11,12 +11,12 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-
 """
 Module for internal utilities.
 """
 
+import os as _os
+import json as _json
 import typing as _typing
 import dataclasses as _dataclasses
 import enum as _enum
@@ -243,3 +243,44 @@ def on_call_check_tokens(request: _Request,) -> _OnCallTokenVerification:
                          log_payload)
 
     return verifications
+
+
+@_dataclasses.dataclass(frozen=True)
+class FirebaseConfig():
+    """
+    A collection of configuration options needed to 
+    initialize a firebase App.
+    """
+
+    storage_bucket: _typing.Optional[str]
+    """
+    The name of the Google Cloud Storage bucket used for storing application data.
+    This is the bucket name without any prefixes or additions (without "gs://").
+    """
+
+    # TODO more to be added later when they are required
+
+
+def firebase_config() -> None | FirebaseConfig:
+    config_file = _os.getenv("FIREBASE_CONFIG")
+    if not config_file:
+        return None
+    if config_file.startswith('{'):
+        json_str = config_file
+    else:
+        # Firebase Tools will always use a JSON blob in prod, but docs
+        # explicitly state that the user can set the env to a file:
+        # https://firebase.google.com/docs/admin/setup#initialize-without-parameters
+        try:
+            with open(config_file, 'r') as json_file:
+                json_str = json_file.read()
+        except Exception as err:
+            raise ValueError('Unable to read file {}. {}'.format(
+                config_file, err))
+    try:
+        json_data: dict = _json.loads(json_str)
+    except Exception as err:
+        raise ValueError(
+            'FIREBASE_CONFIG JSON string "{0}" is not valid json. {1}'.format(
+                json_str, err))
+    return FirebaseConfig(storage_bucket=json_data.get('storageBucket'))

tests/firebase_config_test.json

@@ -0,0 +1,3 @@
+{
+  "storageBucket": "python-functions-testing.appspot.com"
+}

tests/test_util.py

@@ -0,0 +1,42 @@
+# Copyright 2022 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Internal utils tests.
+"""
+from os import environ, path
+from firebase_functions.private.util import firebase_config
+
+test_bucket = "python-functions-testing.appspot.com"
+test_config_file = path.join(path.dirname(path.realpath(__file__)),
+                             "firebase_config_test.json")
+
+
+def test_firebase_config_loads_from_env_json():
+    """
+    Testing firebase_config can be read from the
+    FIREBASE_CONFIG env var as a JSON string.
+    """
+    environ["FIREBASE_CONFIG"] = '{"storageBucket": "%s"}' % test_bucket
+    assert firebase_config().storage_bucket == test_bucket, (
+        "Failure, firebase_config did not load from env variable.")
+
+
+def test_firebase_config_loads_from_env_file():
+    """
+    Testing firebase_config can be read from the
+    FIREBASE_CONFIG env var as a file path.
+    """
+    environ["FIREBASE_CONFIG"] = test_config_file
+    assert firebase_config().storage_bucket == test_bucket, (
+        "Failure, firebase_config did not load from env variable.")