LangChain ↗ is the most popular framework for building AI applications powered by large language models (LLMs).
LangChain publishes multiple Python packages. The following are provided by the Workers runtime:
langchain↗ (version0.1.8)langchain-core↗ (version0.1.25)langchain-openai↗ (version0.0.6)
Clone the cloudflare/python-workers-examples repository and run the LangChain example:
git clone https://github.com/cloudflare/python-workers-examples
cd 05-langchain
uv run pywrangler devfrom workers import WorkerEntrypoint, Response
from langchain_core.prompts import PromptTemplate
from langchain_openai import OpenAI
class Default(WorkerEntrypoint):
async def fetch(self, request):
prompt = PromptTemplate.from_template("Complete the following sentence: I am a {profession} and ")
llm = OpenAI(api_key=self.env.API_KEY)
chain = prompt | llm
res = await chain.ainvoke({"profession": "electrician"})
return Response(res.split(".")[0].strip())