wehub-resource-sync
115 lines
3.2 KiB
Python
115 lines
3.2 KiB
Python
#!/usr/bin/env python
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"""Example LangChain server exposes multiple runnables (LLMs in this case)."""
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from dotenv import load_dotenv
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load_dotenv()
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from fastapi import FastAPI
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from langchain.chat_models import ChatOpenAI
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from langchain.vectorstores import FAISS
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from langchain.embeddings import OpenAIEmbeddings
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from langchain.agents import AgentExecutor, tool
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from langchain.tools.render import format_tool_to_openai_function
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from langchain.prompts import ChatPromptTemplate, MessagesPlaceholder
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from langchain.agents.output_parsers import OpenAIFunctionsAgentOutputParser
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from langchain.pydantic_v1 import BaseModel
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from typing import Any
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from langchain.agents.format_scratchpad import format_to_openai_functions
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from langserve import add_routes
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app = FastAPI(
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title="LangChain Server",
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version="1.0",
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description="Spin up a simple api server using Langchain's Runnable interfaces",
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)
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# ChatOpenAI
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# ----------
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# We probably can't support ChatOpenAI...
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# see input schema: http://localhost:8000/openai/input_schema
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# also playground: http://localhost:8000/openai/playground/
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# it looks tricky to support this in a generic way
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add_routes(
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app,
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ChatOpenAI(),
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path="/openai",
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)
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# Retriever
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# ---------
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# receives a single input VectorStoreRetrieverInput (type string)
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# Input Schema: {"title":"VectorStoreRetrieverInput","type":"string"}
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# according to the client docs, it can be called like this:
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# - requests.post("http://localhost:8000/invoke", json={"input": "tree"})
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# - remote_runnable.invoke("tree")
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vectorstore = FAISS.from_texts(
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["cats like fish", "dogs like sticks"], embedding=OpenAIEmbeddings()
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)
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retriever = vectorstore.as_retriever()
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add_routes(
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app,
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retriever,
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path="/retriever",
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)
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# Agent
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# -----
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# Input Schema: {"title":"Input","type":"object","properties":{"input":{"title":"Input","type":"string"}},"required":["input"]}
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# - requests.post("http://localhost:8000/invoke", json={"input": {"input": "what does eugene think of cats?"}})
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# - remote_runnable.invoke({"input": "what does eugene think of cats?"})
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@tool
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def get_eugene_thoughts(query: str) -> list:
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"""Returns Eugene's thoughts on a topic."""
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return retriever.get_relevant_documents(query)
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tools = [get_eugene_thoughts]
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llm = ChatOpenAI(model="gpt-3.5-turbo", temperature=0, streaming=True)
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llm_with_tools = llm.bind(functions=[format_tool_to_openai_function(t) for t in tools])
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prompt = ChatPromptTemplate.from_messages(
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[
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("system", "You are a helpful assistant."),
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("user", "{input}"),
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MessagesPlaceholder(variable_name="agent_scratchpad"),
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]
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)
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agent = (
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{
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"input": lambda x: x["input"],
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"agent_scratchpad": lambda x: format_to_openai_functions(
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x["intermediate_steps"]
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),
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}
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| prompt
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| llm_with_tools
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| OpenAIFunctionsAgentOutputParser()
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)
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agent_executor = AgentExecutor(graph=agent, tools=tools)
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class Input(BaseModel):
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input: str
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class Output(BaseModel):
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output: Any
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add_routes(
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app,
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agent_executor.with_types(input_type=Input, output_type=Output).with_config(
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{"run_name": "agent"}
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),
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path="/agent",
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)
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if __name__ == "__main__":
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import uvicorn
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uvicorn.run(app, host="localhost", port=8000)
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