LangChain Install & Auth

Name: langchain-install-auth
Rating: 65
Author: vasic-digital

Overview

Set up LangChain SDK and configure LLM provider authentication credentials.

Prerequisites

•Python 3.9+ or Node.js 18+
•Package manager (pip, poetry, or npm)
•LLM provider account (OpenAI, Anthropic, Google, etc.)
•API key from your LLM provider dashboard

Instructions

Step 1: Install LangChain Core

bash

# Python (recommended)
pip install langchain langchain-core langchain-community

# Or with specific providers
pip install langchain-openai langchain-anthropic langchain-google-genai

# Node.js
npm install langchain @langchain/core @langchain/community

Step 2: Configure Authentication

bash

# OpenAI
export OPENAI_API_KEY="your-openai-key"

# Anthropic
export ANTHROPIC_API_KEY="your-anthropic-key"

# Google
export GOOGLE_API_KEY="your-google-key"

# Or create .env file
echo 'OPENAI_API_KEY=your-openai-key' >> .env

Step 3: Verify Connection

python

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(model="gpt-4o-mini")
response = llm.invoke("Say hello!")
print(response.content)

Output

•Installed LangChain packages in virtual environment
•Environment variables or .env file with API keys
•Successful connection verification output

Error Handling

Error	Cause	Solution
Invalid API Key	Incorrect or expired key	Verify key in provider dashboard
Rate Limited	Exceeded quota	Check quota limits, implement backoff
Network Error	Firewall blocking	Ensure outbound HTTPS allowed
Module Not Found	Installation failed	Run `pip install` again, check Python version
Provider Error	Service unavailable	Check provider status page

Examples

Python Setup (OpenAI)

python

import os
from langchain_openai import ChatOpenAI

# Ensure API key is set
assert os.environ.get("OPENAI_API_KEY"), "Set OPENAI_API_KEY"

llm = ChatOpenAI(
    model="gpt-4o-mini",
    temperature=0.7,
    max_tokens=1000
)

Python Setup (Anthropic)

python

from langchain_anthropic import ChatAnthropic

llm = ChatAnthropic(
    model="claude-3-5-sonnet-20241022",
    temperature=0.7
)

TypeScript Setup

typescript

import { ChatOpenAI } from "@langchain/openai";

const llm = new ChatOpenAI({
  modelName: "gpt-4o-mini",
  temperature: 0.7
});

Resources

Next Steps

After successful auth, proceed to langchain-hello-world for your first chain.