Langfuse ✅

Langfuse is an open-source observability platform designed specifically for LLM applications.

Note: Currently, only AI-related calls will contain detailed telemetry data. Other operations will create traces but with limited information.

Configuration ✅

To use Langfuse with Kastrax, you’ll need to configure the following environment variables:


LANGFUSE_PUBLIC_KEY=your_public_key
LANGFUSE_SECRET_KEY=your_secret_key
LANGFUSE_BASEURL=https://cloud.langfuse.com  # Optional - defaults to cloud.langfuse.com

Important: When configuring the telemetry export settings, the traceName parameter must be set to "ai" for the Langfuse integration to work properly.

Implementation ✅

Here’s how to configure Kastrax to use Langfuse:


import { Kastrax } from "@kastrax/core";
import { LangfuseExporter } from "langfuse-vercel";
 
export const kastrax = new Kastrax({
  // ... other config
  telemetry: {
    serviceName: "ai", // this must be set to "ai" so that the LangfuseExporter thinks it's an AI SDK trace
    enabled: true,
    export: {
      type: "custom",
      exporter: new LangfuseExporter({
        publicKey: process.env.LANGFUSE_PUBLIC_KEY,
        secretKey: process.env.LANGFUSE_SECRET_KEY,
        baseUrl: process.env.LANGFUSE_BASEURL,
      }),
    },
  },
});

Dashboard ✅

Once configured, you can view your traces and analytics in the Langfuse dashboard at cloud.langfuse.com