Added client_settings support for chromadb vecstore (#1528)

# Problem

The ChromaDB vecstore only supported local connection. There was no way
to use a chromadb server.

# Fix
Added `client_settings` as Chroma attribute. 

# Usage

```
from chromadb.config import Settings
from langchain.vectorstores import Chroma

chroma_settings = Settings(chroma_api_impl="rest",
                            chroma_server_host="localhost",
                            chroma_server_http_port="80")

docsearch = Chroma.from_documents(chunks, embeddings, metadatas=metadatas, client_settings=chroma_settings, collection_name=COLLECTION_NAME)
```

langchain/vectorstores/chroma.py

@@ -3,12 +3,16 @@ from __future__ import annotations
 
 import logging
 import uuid
-from typing import Any, Dict, Iterable, List, Optional, Tuple
+from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Tuple
 
 from langchain.docstore.document import Document
 from langchain.embeddings.base import Embeddings
 from langchain.vectorstores.base import VectorStore
 
+if TYPE_CHECKING:
+    import chromadb
+    import chromadb.config
+
 logger = logging.getLogger()
 
 
@@ -34,6 +38,7 @@ class Chroma(VectorStore):
         collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
         embedding_function: Optional[Embeddings] = None,
         persist_directory: Optional[str] = None,
+        client_settings: Optional[chromadb.config.Settings] = None,
     ) -> None:
         """Initialize with Chroma client."""
         try:
@@ -45,12 +50,14 @@ class Chroma(VectorStore):
                 "Please install it with `pip install chromadb`."
             )
 
-        # TODO: Add support for custom client. For now this is in-memory only.
-        self._client_settings = chromadb.config.Settings()
-        if persist_directory is not None:
-            self._client_settings = chromadb.config.Settings(
-                chroma_db_impl="duckdb+parquet", persist_directory=persist_directory
-            )
+        if client_settings:
+            self._client_settings = client_settings
+        else:
+            self._client_settings = chromadb.config.Settings()
+            if persist_directory is not None:
+                self._client_settings = chromadb.config.Settings(
+                    chroma_db_impl="duckdb+parquet", persist_directory=persist_directory
+                )
         self._client = chromadb.Client(self._client_settings)
         self._embedding_function = embedding_function
         self._persist_directory = persist_directory
@@ -185,6 +192,7 @@ class Chroma(VectorStore):
         ids: Optional[List[str]] = None,
         collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
         persist_directory: Optional[str] = None,
+        client_settings: Optional[chromadb.config.Settings] = None,
         **kwargs: Any,
     ) -> Chroma:
         """Create a Chroma vectorstore from a raw documents.
@@ -207,6 +215,7 @@ class Chroma(VectorStore):
             collection_name=collection_name,
             embedding_function=embedding,
             persist_directory=persist_directory,
+            client_settings=client_settings,
         )
         chroma_collection.add_texts(texts=texts, metadatas=metadatas, ids=ids)
         return chroma_collection
@@ -219,6 +228,7 @@ class Chroma(VectorStore):
         ids: Optional[List[str]] = None,
         collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
         persist_directory: Optional[str] = None,
+        client_settings: Optional[chromadb.config.Settings] = None,
         **kwargs: Any,
     ) -> Chroma:
         """Create a Chroma vectorstore from a list of documents.
@@ -244,4 +254,5 @@ class Chroma(VectorStore):
             ids=ids,
             collection_name=collection_name,
             persist_directory=persist_directory,
+            client_settings=client_settings,
         )