Ignore name of index when fetching settings

This commit fixes a situation where an index cannot be updated through this client as the index is aliased, with the client pointing to the alias.

As the `GET /<index>/_settings` request will only ever return the settings for the specified index (through the alias), it would only have one key, so the name of the key would not matter. We can pop the key to get the settings object for the index through the alias.

Signed-off-by: Étienne Beaulé <beauleetienne0@gmail.com>

CHANGELOG.md

@@ -8,6 +8,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Removed
 ### Fixed
 - Fix `Transport.perform_request`'s arguments `timeout` and `ignore` variable usage ([810](https://github.com/opensearch-project/opensearch-py/pull/810))
+- Fix `Index.save` not passing through aliases to the underlying index ([823](https://github.com/opensearch-project/opensearch-py/pull/823))
 ### Security
 
 ### Dependencies

opensearchpy/helpers/index.py

@@ -326,7 +326,7 @@ def save(self, using: Optional[OpenSearch] = None) -> Any:
         body = self.to_dict()
         settings = body.pop("settings", {})
         analysis = settings.pop("analysis", None)
-        current_settings = self.get_settings(using=using)[self._name]["settings"][
+        current_settings = self.get_settings(using=using).popitem()[1]["settings"][
             "index"
         ]
         if analysis:

test_opensearchpy/test_server/test_helpers/test_index.py

@@ -122,3 +122,21 @@ def test_multiple_indices_with_same_doc_type_work(write_client: Any) -> None:
         assert settings[j]["settings"]["index"]["analysis"] == {
             "analyzer": {"my_analyzer": {"type": "custom", "tokenizer": "keyword"}}
         }
+
+
+def test_index_can_be_saved_through_alias_with_settings(write_client: Any) -> None:
+    raw_index = Index("test-blog", using=write_client)
+    raw_index.settings(number_of_shards=3, number_of_replicas=0)
+    raw_index.aliases(**{"blog-alias": {}})
+    raw_index.save()
+
+    i = Index("blog-alias", using=write_client)
+    i.settings(number_of_replicas=1)
+    i.save()
+
+    assert (
+        "1"
+        == raw_index.get_settings()["test-blog"]["settings"]["index"][
+            "number_of_replicas"
+        ]
+    )