langfuse-install-auth

# Langfuse Install & Auth ## Overview Install the Langfuse SDK and configure authentication for LLM observability. Covers both the legacy `langfuse` package (v3) and the modern modular SDK (v4+/v5) built on OpenTelemetry. ## Prerequisites - Node.js 18+ or Python 3.9+ - Package manager (npm, pnpm, or pip) - Langfuse account (cloud at https://cloud.langfuse.com or self-hosted) - Public Key (`pk-lf-...`) and Secret Key (`sk-lf-...`) from project settings ## Instructions ### Step 1: Install SDK **TypeScript/JavaScript (v4+ modular SDK -- recommended):** ```bash set -euo pipefail # Core client for prompt management, datasets, scores npm install @langfuse/client # Tracing (observe, startActiveObservation) npm install @langfuse/tracing @langfuse/otel @opentelemetry/sdk-node # OpenAI integration (drop-in wrapper) npm install @langfuse/openai # LangChain integration npm install @langfuse/langchain ``` **TypeScript/JavaScript (v3 legacy -- single package):** ```bash npm install langfuse ``` **Python:** ```bash pip install langfuse ``` ### Step 2: Get API Keys 1. Open Langfuse dashboard (https://cloud.langfuse.com or your self-hosted URL) 2. Go to **Settings > API Keys** 3. Click **Create new API key pair** 4. Copy both keys: - **Public Key**: `pk-lf-...` (identifies your project) - **Secret Key**: `sk-lf-...` (grants write access -- keep secret) 5. Note the host URL (cloud default: `https://cloud.langfuse.com`) ### Step 3: Configure Environment Variables ```bash # S...