Return url for file in GCP public bucket instead of error

src/datachain/client/gcs.py

@@ -32,6 +32,14 @@ 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:
+            if "you need a private key to sign credentials" in str(exc):
+                return f"https://storage.googleapis.com/{self.name}/{path}"
+            raise
+
     @staticmethod
     def parse_timestamp(timestamp: str) -> datetime:
         """

tests/unit/test_client_gcs.py

@@ -0,0 +1,6 @@
+from datachain.client import Client
+
+
+def test_anon_url():
+    client = Client.get_client("gs://foo", None, anon=True)
+    assert client.url("bar") == "https://storage.googleapis.com/foo/bar"