OpenAI + Langsmith integrations- Vercel Serverless API

A serverless API built with Vercel that integrates OpenAI's GPT models with LangSmith

Prerequisites

• Node.js 18+
• Vercel CLI
• OpenAI API Key
• LangSmith API Key and Project

Installation

1. Clone the repository

2. Install dependencies

   npm install

3. install vercel globally

4. Set up environment variables

   Create a .env.local file in the root directory:

   OPENAI_API_KEY=your_openai_api_key_here
   LANGCHAIN_TRACING_V2=true
   LANGCHAIN_API_KEY=your_langsmith_api_key_here
   LANGCHAIN_PROJECT=your_project_name

Local Development

1. Start the development server

   npx run vercel

   The API will be available at http://localhost:3000

2. Test the API endpoint

   curl -X POST http://localhost:3000/api/langsmith_tracing \
     -H "Content-Type: application/json" \
     -d '{
       "model": "gpt-4o",
       "temperature": 0.2,
       "input": [
         {
           "role": "system",
           "content": [
             {
               "type": "input_text",
               "text": "You are a helpful assistant."
             }
           ]
         },
         {
           "role": "user",
           "content": [
             {
               "type": "input_text", 
               "text": "Hello, how are you?"
             }
           ]
         }
       ],
       "text": {"format": {"type": "text"}},
       "store": true
     }'

API Reference

Endpoint: POST - /api/langsmith_tracing

Frontend Integration Examples

JavaScript/Fetch

const response = await fetch('http://localhost:3000/api/langsmith_tracing', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'gpt-4o',
    temperature: 0.2,
    input: [
      {
        role: 'user',
        content: [{
          type: 'input_text',
          text: 'What is the capital of France?'
        }]
      }
    ],
    store: true
  })
});

Deployment

1. Deploy to Vercel

   vercel --prod

2. Set environment variables in Vercel Dashboard
3. Update CORS settings for production:

   res.setHeader('Access-Control-Allow-Origin', 'https://yourdomain.com');

License

MIT License - see LICENSE file for details