Fix OpenSearchDocumentStore's __init__ (#2498)

* Move super in OpenSearchDocumentStore and add small test

* Update Documentation & Code Style

* Add Opensearch container to the CI

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/workflows/linux_ci.yml

@@ -259,6 +259,9 @@ jobs:
     - name: Run Elasticsearch
       run: docker run -d -p 9200:9200 -e "discovery.type=single-node" -e "ES_JAVA_OPTS=-Xms128m -Xmx128m" elasticsearch:7.9.2
 
+    - name: Run Opensearch
+      run: docker run -d -p 9201:9200 -p 9600:9600 -e "discovery.type=single-node" opensearchproject/opensearch:1.2.4
+
     - name: Run Milvus
       run: |
         cd ../../   # Avoid causing permission issues on hashFiles later by creating unreadable folders like "volumes"

haystack/document_stores/elasticsearch.py

@@ -1724,6 +1724,9 @@ def __init__(
                              Synonym or Synonym_graph to handle synonyms, including multi-word synonyms correctly during the analysis process.
                              More info at https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-synonym-graph-tokenfilter.html
         """
+        self.embeddings_field_supports_similarity = False
+        self.similarity_to_space_type = {"cosine": "cosinesimil", "dot_product": "innerproduct", "l2": "l2"}
+        self.space_type_to_similarity = {v: k for k, v in self.similarity_to_space_type.items()}
         super().__init__(
             scheme=scheme,
             username=username,
@@ -1759,9 +1762,6 @@ def __init__(
             synonym_type=synonym_type,
             use_system_proxy=use_system_proxy,
         )
-        self.embeddings_field_supports_similarity = False
-        self.similarity_to_space_type = {"cosine": "cosinesimil", "dot_product": "innerproduct", "l2": "l2"}
-        self.space_type_to_similarity = {v: k for k, v in self.similarity_to_space_type.items()}
 
     def query_by_embedding(
         self,

test/test_document_store.py

@@ -20,7 +20,12 @@
     DC_TEST_INDEX,
     SAMPLES_PATH,
 )
-from haystack.document_stores import WeaviateDocumentStore, DeepsetCloudDocumentStore, InMemoryDocumentStore
+from haystack.document_stores import (
+    OpenSearchDocumentStore,
+    WeaviateDocumentStore,
+    DeepsetCloudDocumentStore,
+    InMemoryDocumentStore,
+)
 from haystack.document_stores.base import BaseDocumentStore
 from haystack.document_stores.es_converter import elasticsearch_index_to_document_store
 from haystack.errors import DuplicateDocumentError
@@ -89,6 +94,11 @@ def test_init_elastic_client():
     _ = ElasticsearchDocumentStore(host=["localhost"], port=[9200], api_key="test", api_key_id="test")
 
 
+@pytest.mark.elasticsearch
+def test_init_opensearch_client():
+    OpenSearchDocumentStore(index="test_index", port=9201)
+
+
 @pytest.mark.elasticsearch
 def test_init_elastic_doc_store_with_index_recreation():
     index_name = "test_index_recreation"