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This module provides automatic instrumentation for LangChain.js which may be used in conjunction with OpenTelemetry.

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Installation

Install the instrumentation package: 
npm install --save @arizeai/openinference-instrumentation-langchain

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Usage

To load the LangChain instrumentation, manually instrument the @langchain/core/callbacks/manager module. The callbacks manager must be manually instrumented due to the non-traditional module structure in @langchain/core. 
import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node";
import { LangChainInstrumentation } from "@arizeai/openinference-instrumentation-langchain";
import * as CallbackManagerModule from "@langchain/core/callbacks/manager";

const provider = new NodeTracerProvider();
provider.register();

const lcInstrumentation = new LangChainInstrumentation();
// LangChain must be manually instrumented as it doesn't have a traditional module structure
lcInstrumentation.manuallyInstrument(CallbackManagerModule);

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TypeScript Example with Custom Tracer Provider

You can specify a custom tracer provider when creating the LangChain instrumentation. This is useful when you want to use a non-global tracer provider or have more control over the tracing configuration. 
import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node";
import { Resource } from "@opentelemetry/resources";
import { SEMRESATTRS_PROJECT_NAME } from "@arizeai/openinference-semantic-conventions";
import { LangChainInstrumentation } from "@arizeai/openinference-instrumentation-langchain";
import * as CallbackManagerModule from "@langchain/core/callbacks/manager";

// Create a custom tracer provider
const customTracerProvider = new NodeTracerProvider({
  resource: new Resource({
    [SEMRESATTRS_PROJECT_NAME]: "my-langchain-project",
  }),
});

// Pass the custom tracer provider to the instrumentation
const lcInstrumentation = new LangChainInstrumentation({
  tracerProvider: customTracerProvider,
});

// Manually instrument the LangChain module
lcInstrumentation.manuallyInstrument(CallbackManagerModule);
Alternatively, you can set the tracer provider after creating the instrumentation: 
const lcInstrumentation = new LangChainInstrumentation();
lcInstrumentation.setTracerProvider(customTracerProvider);

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Compatibility

@langchain/core Version@arizeai/openinference-instrumentation-langchain Version
^1.0.0^4.0.0
^0.3.0^4.0.0
This package is only tested against the 1.X versions of @langchain/core. Older versions may work but are not officially supported. For full compatibility with the 0.X versions of LangChain.js, a dedicated package called @arizeai/openinference-instrumentation-langchain-v0 is available.

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Deprecations

LangChain v0.1 was deprecated on 2025-03-02 due to security vulnerabilities in the core package.

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