metadata

title: DeployPythonicRAG
emoji: 📉
colorFrom: blue
colorTo: purple
sdk: docker
pinned: false
license: apache-2.0

Deploying Pythonic Chat With Your Text File Application

In today's breakout rooms, we will be following the process that you saw during the challenge.

Today, we will repeat the same process - but powered by our Pythonic RAG implementation we created last week.

You'll notice a few differences in the app.py logic - as well as a few changes to the aimakerspace package to get things working smoothly with Chainlit.

NOTE: If you want to run this locally - be sure to use uv sync, and then uv run chainlit run app.py to start the application outside of Docker.

Reference Diagram (It's Busy, but it works)

Anatomy of a Chainlit Application

Chainlit is a Python package similar to Streamlit that lets users write a backend and a front end in a single (or multiple) Python file(s). It is mainly used for prototyping LLM-based Chat Style Applications - though it is used in production in some settings with 1,000,000s of MAUs (Monthly Active Users).

The primary method of customizing and interacting with the Chainlit UI is through a few critical decorators.

NOTE: Simply put, the decorators (in Chainlit) are just ways we can "plug-in" to the functionality in Chainlit.

We'll be concerning ourselves with three main scopes:

On application start - when we start the Chainlit application with a command like chainlit run app.py
On chat start - when a chat session starts (a user opens the web browser to the address hosting the application)
On message - when the users sends a message through the input text box in the Chainlit UI

Let's dig into each scope and see what we're doing!

On Application Start:

The first thing you'll notice is that we have the traditional "wall of imports" this is to ensure we have everything we need to run our application.

import os
from typing import List
from chainlit.types import AskFileResponse
from aimakerspace.text_utils import CharacterTextSplitter, TextFileLoader
from aimakerspace.openai_utils.prompts import (
    UserRolePrompt,
    SystemRolePrompt,
    AssistantRolePrompt,
)
from aimakerspace.openai_utils.embedding import EmbeddingModel
from aimakerspace.vectordatabase import VectorDatabase
from aimakerspace.openai_utils.chatmodel import ChatOpenAI
import chainlit as cl

Next up, we have some prompt templates. As all sessions will use the same prompt templates without modification, and we don't need these templates to be specific per template - we can set them up here - at the application scope.

system_template = """\
Use the following context to answer a users question. If you cannot find the answer in the context, say you don't know the answer."""
system_role_prompt = SystemRolePrompt(system_template)

user_prompt_template = """\
Context:
{context}

Question:
{question}
"""
user_role_prompt = UserRolePrompt(user_prompt_template)

NOTE: You'll notice that these are the exact same prompt templates we used from the Pythonic RAG Notebook in Week 1 Day 2!

Following that - we can create the Python Class definition for our RAG pipeline - or chain, as we'll refer to it in the rest of this walkthrough.

Let's look at the definition first:

class RetrievalAugmentedQAPipeline:
    def __init__(self, llm: ChatOpenAI(), vector_db_retriever: VectorDatabase) -> None:
        self.llm = llm
        self.vector_db_retriever = vector_db_retriever

    async def arun_pipeline(self, user_query: str):
        ### RETRIEVAL
        context_list = self.vector_db_retriever.search_by_text(user_query, k=4)

        context_prompt = ""
        for context in context_list:
            context_prompt += context[0] + "\n"

        ### AUGMENTED
        formatted_system_prompt = system_role_prompt.create_message()

        formatted_user_prompt = user_role_prompt.create_message(question=user_query, context=context_prompt)


        ### GENERATION
        async def generate_response():
            async for chunk in self.llm.astream([formatted_system_prompt, formatted_user_prompt]):
                yield chunk

        return {"response": generate_response(), "context": context_list}

Notice a few things:

We have modified this RetrievalAugmentedQAPipeline from the initial notebook to support streaming.
In essence, our pipeline is chaining a few events together:
1. We take our user query, and chain it into our Vector Database to collect related chunks
2. We take those contexts and our user's questions and chain them into the prompt templates
3. We take that prompt template and chain it into our LLM call
4. We chain the response of the LLM call to the user
We are using a lot of async again!

Now, we're going to create a helper function for processing uploaded text files.

First, we'll instantiate a shared CharacterTextSplitter.

text_splitter = CharacterTextSplitter()

Now we can define our helper.

def process_file(file: AskFileResponse):
    import tempfile
    import shutil
    
    print(f"Processing file: {file.name}")
    
    # Create a temporary file with the correct extension
    suffix = f".{file.name.split('.')[-1]}"
    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as temp_file:
        # Copy the uploaded file content to the temporary file
        shutil.copyfile(file.path, temp_file.name)
        print(f"Created temporary file at: {temp_file.name}")
        
        # Create appropriate loader
        if file.name.lower().endswith('.pdf'):
            loader = PDFLoader(temp_file.name)
        else:
            loader = TextFileLoader(temp_file.name)
            
        try:
            # Load and process the documents
            documents = loader.load_documents()
            texts = text_splitter.split_texts(documents)
            return texts
        finally:
            # Clean up the temporary file
            try:
                os.unlink(temp_file.name)
            except Exception as e:
                print(f"Error cleaning up temporary file: {e}")

Simply put, this downloads the file as a temp file, we load it in with TextFileLoader and then split it with our TextSplitter, and returns that list of strings!

❓ QUESTION #1:

Why do we want to support streaming? What about streaming is important, or useful? Streaming responses from LLMs provides several key benefits:

Improved User Experience: Instead of waiting for the entire response to be generated before seeing anything, users see the response being built word by word, making the interaction feel more natural and engaging, similar to how humans communicate.
Faster First Token Display: Users get immediate feedback that the system is working, rather than staring at a blank screen while waiting for a complete response. This reduces perceived latency and user anxiety.
Memory Efficiency: Streaming processes and displays tokens as they arrive, rather than waiting to buffer the entire response. This is especially important for longer responses that could otherwise consume significant memory.
Early Error Detection: If there are issues with the response generation, they can be detected and handled earlier in the process, rather than waiting for the full response to complete.
Cancellation Capability: Users can potentially cancel long responses midway if they realize they don't need the complete answer, saving both computation time and costs.

In our implementation, we use async streaming to efficiently handle these token-by-token responses while maintaining a responsive user interface.

On Chat Start:

The next scope is where "the magic happens". On Chat Start is when a user begins a chat session. This will happen whenever a user opens a new chat window, or refreshes an existing chat window.

You'll see that our code is set-up to immediately show the user a chat box requesting them to upload a file.

while files == None:
        files = await cl.AskFileMessage(
            content="Please upload a Text or PDF file to begin!",
            accept=["text/plain", "application/pdf"],
            max_size_mb=2,
            timeout=180,
        ).send()

Once we've obtained the text file - we'll use our processing helper function to process our text!

After we have processed our text file - we'll need to create a VectorDatabase and populate it with our processed chunks and their related embeddings!

vector_db = VectorDatabase()
vector_db = await vector_db.abuild_from_list(texts)

Once we have that piece completed - we can create the chain we'll be using to respond to user queries!

retrieval_augmented_qa_pipeline = RetrievalAugmentedQAPipeline(
        vector_db_retriever=vector_db,
        llm=chat_openai
    )

Now, we'll save that into our user session!

NOTE: Chainlit has some great documentation about User Session.

❓ QUESTION #2:

Why are we using User Session here? What about Python makes us need to use this? Why not just store everything in a global variable?

The need for user sessions in Python, particularly in web applications like our Chainlit app, stems from a few key characteristics of Python and web servers:

Process-Based Request Handling: Python web servers typically handle each request in a separate process or thread. Without sessions, variables would be reset between requests because each process has its own memory space. This means global variables wouldn't persist between user interactions.
Memory Isolation: Unlike some desktop applications where state can be maintained in memory throughout the program's lifetime, web applications need to explicitly manage state across multiple requests. Each time a user sends a message, it's a new request that runs in isolation.
Concurrent Users: Multiple users accessing the application simultaneously need their own separate states. Global variables would be shared across all users, leading to data mixing and security issues. User sessions provide isolated storage for each user's conversation context.
Stateless HTTP Protocol: Web applications run over HTTP, which is stateless by nature. Each request is independent and doesn't know about previous requests. Sessions provide a way to maintain state across requests.

In contrast, some other programming environments handle this differently:

JavaScript (Node.js): Can maintain state in closure scope when using WebSocket connections, allowing persistent connections that maintain context without explicit session management.
Elixir/Erlang: Uses the actor model where each user conversation can be a long-lived process (actor) maintaining its own state naturally.
Go: Often uses goroutines that can maintain state for the duration of a user's connection.

By using Chainlit's user session management, we ensure each user has their own isolated vector database and chain instance, preventing cross-talk between different users' conversations and maintaining conversation context properly.

On Message

First, we load our chain from the user session:

chain = cl.user_session.get("chain")

Then, we run the chain on the content of the message - and stream it to the front end - that's it!

msg = cl.Message(content="")
result = await chain.arun_pipeline(message.content)

async for stream_resp in result["response"]:
    await msg.stream_token(stream_resp)

🎉

With that - you've created a Chainlit application that moves our Pythonic RAG notebook to a Chainlit application!

Deploying the Application to Hugging Face Space

Due to the way the repository is created - it should be straightforward to deploy this to a Hugging Face Space!

NOTE: If you wish to go through the local deployments using uv run chainlit run app.py and Docker - please feel free to do so!

Creating a Hugging Face Space

Navigate to the Spaces tab.

Click on Create new Space

Create the Space by providing values in the form. Make sure you've selected "Docker" as your Space SDK.

Adding this Repository to the Newly Created Space

Collect the SSH address from the newly created Space.

NOTE: The address is the component that starts with [email protected]:spaces/.

Use the command:

git remote add hf HF_SPACE_SSH_ADDRESS_HERE

Use the command:

git pull hf main --no-rebase --allow-unrelated-histories -X ours

Use the command:

git add .

Use the command:

git commit -m "Deploying Pythonic RAG"

Use the command:

git push hf main

The Space should automatically build as soon as the push is completed!

NOTE: The build will fail before you complete the following steps!

Adding OpenAI Secrets to the Space

Navigate to your Space settings.

Navigate to Variables and secrets on the Settings page and click New secret:

In the Name field - input OPENAI_API_KEY in the Value (private) field, put your OpenAI API Key.

The Space will begin rebuilding!

🎉

You just deployed Pythonic RAG!

Try uploading a text file and asking some questions!

❓ Discussion Question #1:

Upload a PDF file of the recent DeepSeek-R1 paper and ask the following questions:

What is RL and how does it help reasoning?
- Answered the question correctly, but to me this would qualify as going out of the context since the paper does not explain RL.
What is the difference between DeepSeek-R1 and DeepSeek-R1-Zero?
- Replied correctly with I don't know the answer.
What is this paper about?
- Replied correctly with I don't know the answer, but responds with content for a more specific question like What is DeepSeek-V3

Does this application pass your vibe check? Are there any immediate pitfalls you're noticing?

In my opinion the vibe check failed for the first question.

🚧 CHALLENGE MODE 🚧

For the challenge mode, please instead create a simple FastAPI backend with a simple React (or any other JS framework) frontend.

You can use the same prompt templates and RAG pipeline as we did here - but you'll need to modify the code to work with FastAPI and React.

Deploy this application to Hugging Face Spaces!