Repository: googleapis/python-cloud-core

Issue:
If api_key is set in client options, pass it through to auth
The `ClientOptions` class accepts an `api_key` argument, and the auth library also accepts an `api_key` argument. The `Client` class should pass `ClientOptions.api_key` to the auth library and plumb it all the way through, if it is specified.

Hints from issue comments:

Solution patch:
diff --git a/.kokoro/docker/docs/requirements.txt b/.kokoro/docker/docs/requirements.txt
index d6e9389..a9360a2 100644
--- a/.kokoro/docker/docs/requirements.txt
+++ b/.kokoro/docker/docs/requirements.txt
@@ -8,9 +8,9 @@ argcomplete==3.5.3 \
     --hash=sha256:2ab2c4a215c59fd6caaff41a869480a23e8f6a5f910b266c1808037f4e375b61 \
     --hash=sha256:c12bf50eded8aebb298c7b7da7a5ff3ee24dffd9f5281867dfe1424b58c55392
     # via nox
-cachetools==5.5.1 \
-    --hash=sha256:70f238fbba50383ef62e55c6aff6d9673175fe59f7c6782c7a0b9e38f4a9df95 \
-    --hash=sha256:b76651fdc3b24ead3c648bbdeeb940c1b04d365b38b4af66788f9ec4a81d42bb
+cachetools==5.5.0 \
+    --hash=sha256:02134e8439cdc2ffb62023ce1debca2944c3f289d66bb17ead3ab3dede74b292 \
+    --hash=sha256:2cc24fb4cbe39633fb7badd9db9ca6295d766d9c2995f245725a46715d050f2a
     # via google-auth
 certifi==2024.12.14 \
     --hash=sha256:1275f7a45be9464efc1173084eaa30f866fe2e47d389406136d332ed4967ec56 \
@@ -124,23 +124,23 @@ distlib==0.3.9 \
     --hash=sha256:47f8c22fd27c27e25a65601af709b38e4f0a45ea4fc2e710f65755fa8caaaf87 \
     --hash=sha256:a60f20dea646b8a33f3e7772f74dc0b2d0772d2837ee1342a00645c81edf9403
     # via virtualenv
-filelock==3.17.0 \
-    --hash=sha256:533dc2f7ba78dc2f0f531fc6c4940addf7b70a481e269a5a3b93be94ffbe8338 \
-    --hash=sha256:ee4e77401ef576ebb38cd7f13b9b28893194acc20a8e68e18730ba9c0e54660e
+filelock==3.16.1 \
+    --hash=sha256:2082e5703d51fbf98ea75855d9d5527e33d8ff23099bec374a134febee6946b0 \
+    --hash=sha256:c249fbfcd5db47e5e2d6d62198e565475ee65e4831e2561c8e313fa7eb961435
     # via virtualenv
 gcp-docuploader==0.6.5 \
     --hash=sha256:30221d4ac3e5a2b9c69aa52fdbef68cc3f27d0e6d0d90e220fc024584b8d2318 \
     --hash=sha256:b7458ef93f605b9d46a4bf3a8dc1755dad1f31d030c8679edf304e343b347eea
     # via -r requirements.in
-google-api-core==2.24.1 \
-    --hash=sha256:bc78d608f5a5bf853b80bd70a795f703294de656c096c0968320830a4bc280f1 \
-    --hash=sha256:f8b36f5456ab0dd99a1b693a40a31d1e7757beea380ad1b38faaf8941eae9d8a
+google-api-core==2.24.0 \
+    --hash=sha256:10d82ac0fca69c82a25b3efdeefccf6f28e02ebb97925a8cce8edbfe379929d9 \
+    --hash=sha256:e255640547a597a4da010876d333208ddac417d60add22b6851a0c66a831fcaf
     # via
     #   google-cloud-core
     #   google-cloud-storage
-google-auth==2.38.0 \
-    --hash=sha256:8285113607d3b80a3f1543b75962447ba8a09fe85783432a784fdeef6ac094c4 \
-    --hash=sha256:e7dae6694313f434a2727bf2906f27ad259bae090d7aa896590d86feec3d9d4a
+google-auth==2.37.0 \
+    --hash=sha256:0054623abf1f9c83492c63d3f47e77f0a544caa3d40b2d98e099a611c2dd5d00 \
+    --hash=sha256:42664f18290a6be591be5329a96fe30184be1a1badb7292a7f686a9659de9ca0
     # via
     #   google-api-core
     #   google-cloud-core
@@ -149,9 +149,9 @@ google-cloud-core==2.4.1 \
     --hash=sha256:9b7749272a812bde58fff28868d0c5e2f585b82f37e09a1f6ed2d4d10f134073 \
     --hash=sha256:a9e6a4422b9ac5c29f79a0ede9485473338e2ce78d91f2370c01e730eab22e61
     # via google-cloud-storage
-google-cloud-storage==3.0.0 \
-    --hash=sha256:2accb3e828e584888beff1165e5f3ac61aa9088965eb0165794a82d8c7f95297 \
-    --hash=sha256:f85fd059650d2dbb0ac158a9a6b304b66143b35ed2419afec2905ca522eb2c6a
+google-cloud-storage==2.19.0 \
+    --hash=sha256:aeb971b5c29cf8ab98445082cbfe7b161a1f48ed275822f59ed3f1524ea54fba \
+    --hash=sha256:cd05e9e7191ba6cb68934d8eb76054d9be4562aa89dbc4236feee4d7d51342b2
     # via gcp-docuploader
 google-crc32c==1.6.0 \
     --hash=sha256:05e2d8c9a2f853ff116db9706b4a27350587f341eda835f46db3c0a8c8ce2f24 \
@@ -208,9 +208,9 @@ platformdirs==4.3.6 \
     --hash=sha256:357fb2acbc885b0419afd3ce3ed34564c13c9b95c89360cd9563f73aa5e2b907 \
     --hash=sha256:73e575e1408ab8103900836b97580d5307456908a03e92031bab39e4554cc3fb
     # via virtualenv
-proto-plus==1.26.0 \
-    --hash=sha256:6e93d5f5ca267b54300880fff156b6a3386b3fa3f43b1da62e680fc0c586ef22 \
-    --hash=sha256:bf2dfaa3da281fc3187d12d224c707cb57214fb2c22ba854eb0c105a3fb2d4d7
+proto-plus==1.25.0 \
+    --hash=sha256:c91fc4a65074ade8e458e95ef8bac34d4008daa7cce4a12d6707066fca648961 \
+    --hash=sha256:fbb17f57f7bd05a68b7707e745e26528b0b3c34e378db91eef93912c54982d91
     # via google-api-core
 protobuf==5.29.3 \
     --hash=sha256:0a18ed4a24198528f2333802eb075e59dea9d679ab7a6c5efb017a59004d849f \
@@ -291,7 +291,7 @@ urllib3==2.3.0 \
     --hash=sha256:1cee9ad369867bfdbbb48b7dd50374c0967a0bb7710050facf0dd6911440e3df \
     --hash=sha256:f8c5449b3cf0861679ce7e0503c7b44b5ec981bec0d1d3795a07f1ba96f0204d
     # via requests
-virtualenv==20.29.1 \
-    --hash=sha256:4e4cb403c0b0da39e13b46b1b2476e505cb0046b25f242bee80f62bf990b2779 \
-    --hash=sha256:b8b8970138d32fb606192cb97f6cd4bb644fa486be9308fb9b63f81091b5dc35
+virtualenv==20.28.1 \
+    --hash=sha256:412773c85d4dab0409b83ec36f7a6499e72eaf08c80e81e9576bca61831c71cb \
+    --hash=sha256:5d34ab240fdb5d21549b76f9e8ff3af28252f5499fb6d6f031adac4e5a8c5329
     # via nox
diff --git a/google/cloud/client/__init__.py b/google/cloud/client/__init__.py
index 93e5d22..1396486 100644
--- a/google/cloud/client/__init__.py
+++ b/google/cloud/client/__init__.py
@@ -30,6 +30,13 @@ import google.auth.transport.requests
 from google.cloud._helpers import _determine_default_project
 from google.oauth2 import service_account
 
+try:
+    import google.auth.api_key
+
+    HAS_GOOGLE_AUTH_API_KEY = True
+except ImportError:
+    HAS_GOOGLE_AUTH_API_KEY = False
+
 
 _GOOGLE_AUTH_CREDENTIALS_HELP = (
     "This library only supports credentials from google-auth-library-python. "
@@ -161,6 +168,15 @@ class Client(_ClientFactoryMixin):
                 "'credentials' and 'client_options.credentials_file' are mutually exclusive."
             )
 
+        if (
+            HAS_GOOGLE_AUTH_API_KEY
+            and client_options.api_key
+            and (credentials or client_options.credentials_file)
+        ):
+            raise google.api_core.exceptions.DuplicateCredentialArgs(
+                "'client_options.api_key' is mutually exclusive with 'credentials' and 'client_options.credentials_file'."
+            )
+
         if credentials and not isinstance(
             credentials, google.auth.credentials.Credentials
         ):
@@ -174,6 +190,8 @@ class Client(_ClientFactoryMixin):
                 credentials, _ = google.auth.load_credentials_from_file(
                     client_options.credentials_file, scopes=scopes
                 )
+            elif HAS_GOOGLE_AUTH_API_KEY and client_options.api_key is not None:
+                credentials = google.auth.api_key.Credentials(client_options.api_key)
             else:
                 credentials, _ = google.auth.default(scopes=scopes)
 


Test patch:
diff --git a/tests/unit/test_client.py b/tests/unit/test_client.py
index fb35da4..943b422 100644
--- a/tests/unit/test_client.py
+++ b/tests/unit/test_client.py
@@ -17,6 +17,8 @@ import json
 import unittest
 from unittest import mock
 
+from google.cloud.client import HAS_GOOGLE_AUTH_API_KEY
+
 
 def _make_credentials():
     import google.auth.credentials
@@ -75,6 +77,19 @@ class TestClient(unittest.TestCase):
         self.assertIs(client_obj._credentials, credentials)
         self.assertIs(client_obj._http_internal, http)
 
+    @unittest.skipIf(
+        not HAS_GOOGLE_AUTH_API_KEY, "Auth library version does not support API keys"
+    )
+    def test_ctor_client_options_w_api_key(self):
+        from google.auth.api_key import Credentials
+
+        API_KEY = "my_api_key"
+
+        client_options = {"api_key": API_KEY}
+        client_obj = self._make_one(client_options=client_options)
+
+        self.assertIsInstance(client_obj._credentials, Credentials)
+
     def test_ctor_client_options_w_conflicting_creds(self):
         from google.api_core.exceptions import DuplicateCredentialArgs
 
@@ -83,6 +98,19 @@ class TestClient(unittest.TestCase):
         with self.assertRaises(DuplicateCredentialArgs):
             self._make_one(credentials=credentials, client_options=client_options)
 
+    @unittest.skipIf(
+        not HAS_GOOGLE_AUTH_API_KEY, "Auth library version does not support API keys"
+    )
+    def test_ctor_client_options_w_api_key_and_conflicting_creds(self):
+        from google.api_core.exceptions import DuplicateCredentialArgs
+
+        API_KEY = "my_api_key"
+
+        credentials = _make_credentials()
+        client_options = {"api_key": API_KEY}
+        with self.assertRaises(DuplicateCredentialArgs):
+            self._make_one(credentials=credentials, client_options=client_options)
+
     def test_ctor_bad_credentials(self):
         credentials = mock.sentinel.credentials