feat: Add an OOTB Chat uI to the Feature Server to support RAG demo

MANIFEST.in

@@ -7,3 +7,4 @@ prune examples
 
 graft sdk/python/feast/ui/build
 graft sdk/python/feast/embedded_go/lib
+recursive-include sdk/python/feast/static *

sdk/python/feast/feature_server.py

@@ -1,17 +1,29 @@
+import asyncio
+import os
 import sys
 import threading
 import time
 import traceback
 from contextlib import asynccontextmanager
+from importlib import resources as importlib_resources
 from typing import Any, Dict, List, Optional
 
 import pandas as pd
 import psutil
 from dateutil import parser
-from fastapi import Depends, FastAPI, Request, Response, status
+from fastapi import (
+    Depends,
+    FastAPI,
+    Request,
+    Response,
+    WebSocket,
+    WebSocketDisconnect,
+    status,
+)
 from fastapi.concurrency import run_in_threadpool
 from fastapi.logger import logger
 from fastapi.responses import JSONResponse
+from fastapi.staticfiles import StaticFiles
 from google.protobuf.json_format import MessageToDict
 from prometheus_client import Gauge, start_http_server
 from pydantic import BaseModel
@@ -78,6 +90,15 @@ class GetOnlineFeaturesRequest(BaseModel):
     query_string: Optional[str] = None
 
 
+class ChatMessage(BaseModel):
+    role: str
+    content: str
+
+
+class ChatRequest(BaseModel):
+    messages: List[ChatMessage]
+
+
 def _get_features(request: GetOnlineFeaturesRequest, store: "feast.FeatureStore"):
     if request.feature_service:
         feature_service = store.get_feature_service(
@@ -113,6 +134,35 @@ def get_app(
     store: "feast.FeatureStore",
     registry_ttl_sec: int = DEFAULT_FEATURE_SERVER_REGISTRY_TTL,
 ):
+    """
+    Creates a FastAPI app that can be used to start a feature server.
+
+    Args:
+        store: The FeatureStore to use for serving features
+        registry_ttl_sec: The TTL in seconds for the registry cache
+
+    Returns:
+        A FastAPI app
+
+    Example:
+        ```python
+        from feast import FeatureStore
+
+        store = FeatureStore(repo_path="feature_repo")
+        app = get_app(store)
+        ```
+
+    The app provides the following endpoints:
+    - `/get-online-features`: Get online features
+    - `/retrieve-online-documents`: Retrieve online documents
+    - `/push`: Push features to the feature store
+    - `/write-to-online-store`: Write to the online store
+    - `/health`: Health check
+    - `/materialize`: Materialize features
+    - `/materialize-incremental`: Materialize features incrementally
+    - `/chat`: Chat UI
+    - `/ws/chat`: WebSocket endpoint for chat
+    """
     proto_json.patch()
     # Asynchronously refresh registry, notifying shutdown and canceling the active timer if the app is shutting down
     registry_proto = None
@@ -297,6 +347,21 @@ async def health():
             else Response(status_code=status.HTTP_503_SERVICE_UNAVAILABLE)
         )
 
+    @app.post("/chat")
+    async def chat(request: ChatRequest):
+        # Process the chat request
+        # For now, just return dummy text
+        return {"response": "This is a dummy response from the Feast feature server."}
+
+    @app.get("/chat")
+    async def chat_ui():
+        # Serve the chat UI
+        static_dir_ref = importlib_resources.files(__spec__.parent) / "static/chat"  # type: ignore[name-defined, arg-type]
+        with importlib_resources.as_file(static_dir_ref) as static_dir:
+            with open(os.path.join(static_dir, "index.html")) as f:
+                content = f.read()
+        return Response(content=content, media_type="text/html")
+
     @app.post("/materialize", dependencies=[Depends(inject_user_details)])
     def materialize(request: MaterializeRequest) -> None:
         for feature_view in request.feature_views or []:
@@ -337,6 +402,46 @@ async def rest_exception_handler(request: Request, exc: Exception):
                 content=str(exc),
             )
 
+    # Chat WebSocket connection manager
+    class ConnectionManager:
+        def __init__(self):
+            self.active_connections: List[WebSocket] = []
+
+        async def connect(self, websocket: WebSocket):
+            await websocket.accept()
+            self.active_connections.append(websocket)
+
+        def disconnect(self, websocket: WebSocket):
+            self.active_connections.remove(websocket)
+
+        async def send_message(self, message: str, websocket: WebSocket):
+            await websocket.send_text(message)
+
+    manager = ConnectionManager()
+
+    @app.websocket("/ws/chat")
+    async def websocket_endpoint(websocket: WebSocket):
+        await manager.connect(websocket)
+        try:
+            while True:
+                message = await websocket.receive_text()
+                # Process the received message (currently unused but kept for future implementation)
+                # For now, just return dummy text
+                response = f"You sent: '{message}'. This is a dummy response from the Feast feature server."
+
+                # Stream the response word by word
+                words = response.split()
+                for word in words:
+                    await manager.send_message(word + " ", websocket)
+                    await asyncio.sleep(0.1)  # Add a small delay between words
+        except WebSocketDisconnect:
+            manager.disconnect(websocket)
+
+    # Mount static files
+    static_dir_ref = importlib_resources.files(__spec__.parent) / "static"  # type: ignore[name-defined, arg-type]
+    with importlib_resources.as_file(static_dir_ref) as static_dir:
+        app.mount("/static", StaticFiles(directory=static_dir), name="static")
+
     return app
 
 

sdk/python/feast/static/chat/index.html

@@ -0,0 +1,129 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Feast Chat</title>
+    <style>
+        body {
+            font-family: Arial, sans-serif;
+            margin: 0;
+            padding: 0;
+            display: flex;
+            flex-direction: column;
+            height: 100vh;
+        }
+        .chat-container {
+            flex: 1;
+            display: flex;
+            flex-direction: column;
+            padding: 20px;
+            overflow-y: auto;
+        }
+        .message {
+            margin-bottom: 10px;
+            padding: 10px;
+            border-radius: 5px;
+            max-width: 70%;
+        }
+        .user-message {
+            background-color: #e6f7ff;
+            align-self: flex-end;
+        }
+        .bot-message {
+            background-color: #f0f0f0;
+            align-self: flex-start;
+        }
+        .input-container {
+            display: flex;
+            padding: 10px;
+            border-top: 1px solid #ccc;
+        }
+        #message-input {
+            flex: 1;
+            padding: 10px;
+            border: 1px solid #ccc;
+            border-radius: 5px;
+            margin-right: 10px;
+        }
+        #send-button {
+            padding: 10px 20px;
+            background-color: #1890ff;
+            color: white;
+            border: none;
+            border-radius: 5px;
+            cursor: pointer;
+        }
+    </style>
+</head>
+<body>
+    <div class="chat-container" id="chat-container">
+        <div class="message bot-message">Hello! How can I help you today?</div>
+    </div>
+    <div class="input-container">
+        <input type="text" id="message-input" placeholder="Type your message...">
+        <button id="send-button">Send</button>
+    </div>
+    <script>
+        const chatContainer = document.getElementById('chat-container');
+        const messageInput = document.getElementById('message-input');
+        const sendButton = document.getElementById('send-button');
+
+        // WebSocket connection
+        const ws = new WebSocket(`ws://${window.location.host}/ws/chat`);
+
+        ws.onmessage = function(event) {
+            // Check if there's an existing bot message being built
+            const lastMessage = chatContainer.lastElementChild;
+            if (lastMessage && lastMessage.classList.contains('bot-message') && lastMessage.dataset.streaming === 'true') {
+                // Append to the existing message
+                lastMessage.textContent += event.data;
+            } else {
+                // Create a new bot message
+                const botMessage = document.createElement('div');
+                botMessage.classList.add('message', 'bot-message');
+                botMessage.dataset.streaming = 'true';
+                botMessage.textContent = event.data;
+                chatContainer.appendChild(botMessage);
+                chatContainer.scrollTop = chatContainer.scrollHeight;
+            }
+        };
+
+        ws.onclose = function(event) {
+            console.log('Connection closed');
+            // Mark the last message as complete if it was streaming
+            const lastMessage = chatContainer.lastElementChild;
+            if (lastMessage && lastMessage.classList.contains('bot-message') && lastMessage.dataset.streaming === 'true') {
+                lastMessage.dataset.streaming = 'false';
+            }
+        };
+
+        function sendMessage() {
+            const message = messageInput.value.trim();
+            if (message) {
+                // Add user message to chat
+                const userMessage = document.createElement('div');
+                userMessage.classList.add('message', 'user-message');
+                userMessage.textContent = message;
+                chatContainer.appendChild(userMessage);
+
+                // Send message to server
+                ws.send(message);
+
+                // Clear input
+                messageInput.value = '';
+
+                // Scroll to bottom
+                chatContainer.scrollTop = chatContainer.scrollHeight;
+            }
+        }
+
+        sendButton.addEventListener('click', sendMessage);
+        messageInput.addEventListener('keypress', function(event) {
+            if (event.key === 'Enter') {
+                sendMessage();
+            }
+        });
+    </script>
+</body>
+</html>

sdk/python/feast/ui_server.py

@@ -69,6 +69,8 @@ def shutdown_event():
 
     @app.get("/registry")
     def read_registry():
+        if registry_proto is None:
+            return Response(status_code=503)  # Service Unavailable
         return Response(
             content=registry_proto.SerializeToString(),
             media_type="application/octet-stream",