langchain/templates/README.md

LangServe Templates

Templates for a fully functioning app that can be hosted by LangServe.

Some other helpful docs:

• [Templates]

Usage

To use, first install the LangChain CLI.

pip install -U langchain-cli

Then, install langserve:

pip install -U "langserve[all]"

Next, create a new LangChain project:

langchain serve new my-app

This will create a new directory called my-app with two folders:

• app: This is where LangServe code will live
• packages: This is where your chains or agents will live

To pull in an existing template as a package, you first need to go into your new project:

cd my-app

And you can the add a template as a project

langchain serve add $PROJECT_NAME

This will pull in the specified template into packages/$PROJECT_NAME

You then need to install this package so you can use it in the langserve app:

pip install -e packages/$PROJECT_NAME

We install it with -e so that if you modify the template at all (which you likely will) the changes are updated.

In order to have LangServe use this project, you then need to modify app/server.py. Specifically, you should add something like:

from fastapi import FastAPI
from langserve import add_routes
# This depends on the structure of the package you install
from my_project import chain

app = FastAPI()

add_routes(app, chain)

You can then spin up production-ready endpoints, along with a playground, by running:

langchain start

Adding a template

See here