langchain-integration.md

title	page nav LangChain Integration LangChain Integration
description	Add guardrails to LangChain chains or use chains as actions inside guardrails configurations.
topics	Integration AI Safety
tags	LangChain RunnableRails Actions LangSmith
content	type difficulty audience how_to technical_intermediate engineer AI Engineer

LangChain Integration

There are two main ways in which you can use the NeMo Guardrails library with LangChain:

1. Add guardrails to a LangChain chain (or Runnable).
2. Use a LangChain chain (or Runnable) inside a guardrails configuration.

Add Guardrails to a Chain

You can easily add guardrails to a chain using the RunnableRails class:

from nemoguardrails import RailsConfig
from nemoguardrails.integrations.langchain.runnable_rails import RunnableRails

# ... initialize `some_chain`

config = RailsConfig.from_path("path/to/config")

# Using LCEL, you first create a RunnableRails instance, and "apply" it using the "|" operator
guardrails = RunnableRails(config)
chain_with_guardrails = guardrails | some_chain

# Alternatively, you can specify the Runnable to wrap
# when creating the RunnableRails instance.
chain_with_guardrails = RunnableRails(config, runnable=some_chain)

For more details, check out the RunnableRails Guide and the Chain with Guardrails Guide.

Using a Chain inside Guardrails

To use a chain (or Runnable) inside a guardrails configuration, you can register it as an action.

from nemoguardrails import RailsConfig, LLMRails

config = RailsConfig.from_path("path/to/config")
rails = LLMRails(config)

rails.register_action(SampleChainOrRunnable(), "sample_action")

Once registered, the chain (or Runnable) can be invoked from within a flow:

define flow
  ...
  $result = execute sample_action
  ...

For a complete example, check out the Runnable as Action Guide.

LangSmith Integration

The NeMo Guardrails library integrates out-of-the-box with LangSmith. To start sending trace information to LangSmith, you have to configure the following environment variables:

export LANGCHAIN_TRACING_V2=true
export LANGCHAIN_ENDPOINT=https://api.smith.langchain.com
export LANGCHAIN_API_KEY=<your-api-key>
export LANGCHAIN_PROJECT=<your-project>  # if not specified, defaults to "default"

For more details on configuring LangSmith check out the LangSmith documentation.