Chroma component silently returns [] with chromadb >=1.0 remote server (Client(settings=) deprecated)

[sabarishtm]

Description

The ChromaVectorStoreComponent in lfx/components/chroma/chroma.py uses the deprecated chromadb.Client(settings=Settings(chroma_server_host=...)) pattern to connect to a remote Chroma server. On chromadb >= 1.0, this call silently creates a local in-memory ephemeral database and ignores chroma_server_host entirely — no error, no warning.

Every query against the component succeeds with dataframe: [] regardless of how much real data exists in the configured remote server.

Environment

• Langflow: 1.8.4
• chromadb: 1.5.5
• langchain-chroma: latest
• Remote ChromaDB: host.docker.internal:8100 (75 documents in collection)

Reproduction

1. Run a standalone ChromaDB server (e.g. docker run -p 8100:8000 chromadb/chroma)
2. Ingest documents into a collection using chromadb.HttpClient + pre-computed embeddings
3. In Langflow, create a flow with: Chat Input → Chroma DB node → Parser → Prompt Template → Language Model
4. Configure the Chroma DB node with chroma_server_host and chroma_server_http_port pointing at the remote server, correct collection name, and an Ollama/OpenAI embedding node matching the ingest model
5. Send a query through the flow

Expected: Chroma DB node returns results from the remote collection.
Actual: Chroma DB node returns dataframe: []. Execution time ~95ms (no network call happened). All downstream nodes process empty context.

Root cause

In lfx/components/chroma/chroma.py:build_vector_store():

if self.chroma_server_host:
    chroma_settings = Settings(
        chroma_server_cors_allow_origins=self.chroma_server_cors_allow_origins or [],
        chroma_server_host=self.chroma_server_host,
        chroma_server_http_port=self.chroma_server_http_port or None,
        chroma_server_grpc_port=self.chroma_server_grpc_port or None,
        chroma_server_ssl_enabled=self.chroma_server_ssl_enabled,
    )
    client = Client(settings=chroma_settings)

On chromadb 1.0+, Client(settings=Settings(chroma_server_host=...)) no longer connects to a remote server — it creates a local ephemeral in-memory database. The server-related settings fields are silently ignored.

Minimal reproducer (run inside the Langflow container)

import chromadb
from chromadb.config import Settings

# This is what Langflow does — BROKEN on chromadb >= 1.0
settings = Settings(chroma_server_host='host.docker.internal', chroma_server_http_port=8100)
client_broken = chromadb.Client(settings=settings)
print(client_broken.list_collections())  # → []  (local ephemeral DB, ignores remote)

# This is the correct approach
client_working = chromadb.HttpClient(host='host.docker.internal', port=8100)
print(client_working.list_collections())  # → [<real collections with real data>]

Proposed fix

Replace the Client(settings=...) call with HttpClient(host=..., port=..., ssl=...):

from chromadb import HttpClient

client = None
if self.chroma_server_host:
    client = HttpClient(
        host=self.chroma_server_host,
        port=self.chroma_server_http_port or 8000,
        ssl=bool(self.chroma_server_ssl_enabled),
    )

The Settings import can be removed entirely.

Additional note for maintainers

When applying the fix, remember to regenerate lfx/_assets/component_index.json — that file contains a serialized copy of each component's source code under entries[*][1]["Chroma"]["template"]["code"]["value"], and Langflow's flow runner executes the code string from the JSON, not from the .py file. Patching only the .py file has no effect on actual flow execution — we verified this empirically by mounting a patched .py that worked perfectly via direct import but had zero impact on flow runs until the JSON was also updated.

Current workaround

Volume-mount a patched chroma.py and a patched component_index.json into the container:

# docker-compose.yml
langflow:
  volumes:
    - ./patches/chroma.py:/app/.venv/lib/python3.12/site-packages/lfx/components/chroma/chroma.py:ro
    - ./patches/component_index.json:/app/.venv/lib/python3.12/site-packages/lfx/_assets/component_index.json:ro