Editing Openai/694ab010-3e7c-8000-b0e8-b98c22b7a063 (section)

===== This uses LangChain but keeps logic very simple. For a real chatbot you would add memory, retrieval, tools, etc. =====

<syntaxhighlight lang="python">import os
import streamlit as st

from langchain_openai import ChatOpenAI
from langchain_core.messages import HumanMessage, SystemMessage

st.set_page_config(page_title="ML Chatbot", layout="centered")
st.title("Simple ML Chatbot (LangChain + Streamlit)")

=== Read API key from environment variable ===
OPENAI_API_KEY = os.getenv("OPENAI_API_KEY", "")

if not OPENAI_API_KEY:
    st.warning("OPENAI_API_KEY is not set. The chatbot will not work until you set it.")
else:
    llm = ChatOpenAI(model="gpt-4o-mini", temperature=0.2)

if "history" not in st.session_state:
    st.session_state.history = []

prompt = st.chat_input("Ask something...")

if prompt:
    st.session_state.history.append(("user", prompt))

    if not OPENAI_API_KEY:
        reply = "OPENAI_API_KEY missing. Set it as an environment variable and restart."
    else:
        messages = [SystemMessage(content="You are a helpful assistant.")]
        for role, text in st.session_state.history:
            if role == "user":
                messages.append(HumanMessage(content=text))
            else:
                # assistant messages can be added too, kept simple here
                pass

        resp = llm.invoke(messages)
        reply = resp.content

    st.session_state.history.append(("assistant", reply))

for role, text in st.session_state.history:
    with st.chat_message(role):
        st.write(text)

</syntaxhighlight>

===== <syntaxhighlight lang="txt">streamlit==1.39.0 =====
langchain==0.2.16
langchain-openai==0.1.22

</syntaxhighlight>

===== <syntaxhighlight lang="dockerfile">FROM python:3.11-slim =====

WORKDIR /app

=== System packages (optional but often useful) ===
RUN apt-get update && apt-get install -y --no-install-recommends \
    curl \
  && rm -rf /var/lib/apt/lists/*

COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

COPY app.py .

=== Streamlit runs on 8501 by default ===
EXPOSE 8501

=== Streamlit in container must listen on 0.0.0.0 ===
CMD ["streamlit", "run", "app.py", "--server.address=0.0.0.0", "--server.port=8501"]

</syntaxhighlight>