open_search_index_to_document_store fails to recognize OpenSearch server

[ghost]

I am running into unexpected behavior when trying to use an existing OpenSearch index as a DocumentStore.
First I set a DocumentStore object:

from haystack.document_stores import OpenSearchDocumentStore, open_search_index_to_document_store

document_store = OpenSearchDocumentStore(scheme="https",
                                         host="myhost.com",
                                         port=443,
                                         username="admin", 
                                         password="admin"
                                         )

When using this object for creating a new document_store with open_search_index_to_document_store(), the process fails due to open_search_index_to_document_store() defaulting back to https://localhost:9200/:

new_ds = open_search_index_to_document_store(
    document_store=document_store,
    original_index_name="myindex",
    original_content_field="mycontent"
)

This results in: NewConnectionError(<urllib3.connection.HTTPSConnection object at 0x7eff75f442b0>: Failed to establish a new connection: [Errno 111] Connection refused). Due to WARNING:elasticsearch:GET https://localhost:9200/ [status:N/A request:0.001s] I presume that the proper host from document_store was not passed on.

To rectify this I do it manually:

new_ds = open_search_index_to_document_store(
    document_store=document_store,
    host="myhost.com",
    port=443,
    original_index_name="myindex",
    original_content_field="mycontent"
)

This results in AuthenticationException: AuthenticationException(401, 'Unauthorized'), meaning that I need to add my credentials as well, which I do:

new_ds = open_search_index_to_document_store(
    document_store=document_store,
    host="myhost.com",
    port=443,
    original_index_name="myindex",
    original_content_field="mycontent",
    username="admin",
    password="admin"
)

And this results in UnsupportedProductError: The client noticed that the server is not Elasticsearch and we do not support this unknown product.
This is where I am at my wits end. I am definitely using a OpenSearch server and do not understand why this function suddenly expects ElasticSearch.
Does anyone know what is happening here? I suspect that I'm using the classes wrong, but do not understand how to do it properly without a working example.

[juiwenchen]

Same problem. I am trying to import the indexed document from OpenSearch to DocumentStore.

I noticed headers.get("x-elastic-product", None) != "Elasticsearch" on line 665 in transport.py might be the reason why it fails.