Return url for file in GCP public bucket instead of error

src/datachain/client/gcs.py

@@ -33,13 +33,21 @@ def create_fs(cls, **kwargs) -> GCSFileSystem:
         return cast(GCSFileSystem, super().create_fs(**kwargs))
 
     def url(self, path: str, expires: int = 3600, **kwargs) -> str:
-        try:
-            return self.fs.sign(self.get_full_path(path), expiration=expires, **kwargs)
-        except AttributeError as exc:
-            is_anon = self.fs.storage_options.get("token") == "anon"
-            if is_anon and "you need a private key to sign credentials" in str(exc):
-                return f"https://storage.googleapis.com/{self.name}/{path}"
-            raise
+        """
+        Generate a signed URL for the given path.
+        If the client is anonymous, a public URL is returned instead.
+        """
+        fs = cast(GCSFileSystem, self.fs)
+        if fs.storage_options.get("token") == "anon":
+            return self.public_url(path)
+        return fs.sign(self.get_full_path(path), expiration=expires, **kwargs)
+
+    def public_url(self, path: str) -> str:
+        """
+        Generate a public URL for the given path.
+        See https://cloud.google.com/storage/docs/access-public-data#api-link
+        """
+        return f"https://storage.googleapis.com/{self.name}/{path}"
 
     @staticmethod
     def parse_timestamp(timestamp: str) -> datetime:

tests/unit/test_client_gcs.py

@@ -1,17 +1,6 @@
 from datachain.client import Client
 
 
-def test_anon_url(mocker):
-    def sign(*args, **kwargs):
-        raise AttributeError(
-            "you need a private key to sign credentials."
-            "the credentials you are currently using"
-            " <class 'google.oauth2.credentials.Credentials'> just contains a token."
-            " see https://googleapis.dev/python/google-api-core/latest/auth.html"
-            "#setting-up-a-service-account for more details."
-        )
-
-    mocker.patch("gcsfs.GCSFileSystem.sign", side_effect=sign)
-
+def test_anon_url():
     client = Client.get_client("gs://foo", None, anon=True)
     assert client.url("bar") == "https://storage.googleapis.com/foo/bar"