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Langfuse environment variables setup

Q: Langfuse environment variables setup

Set the LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY environment variables to authenticate the Langfuse Python SDK. These keys enable secure tracing and observability of your AI API calls when using the Langfuse client.

Quick answer

Set the LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY environment variables to authenticate the Langfuse Python SDK. These keys enable secure tracing and observability of your AI API calls when using the Langfuse client.

PREREQUISITES

Python 3.8+
Langfuse API keys (public and secret)
pip install langfuse

Setup

Install the Langfuse Python SDK and set the required environment variables for authentication. The SDK requires both LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY to function properly.

bash

pip install langfuse

Step by step

Here is a complete example demonstrating how to set environment variables in your shell and initialize the Langfuse client in Python.

bash

# In your shell (Linux/macOS)
export LANGFUSE_PUBLIC_KEY="your_public_key_here"
export LANGFUSE_SECRET_KEY="your_secret_key_here"

# In Python script
import os
from langfuse import Langfuse

langfuse = Langfuse(
    public_key=os.environ["LANGFUSE_PUBLIC_KEY"],
    secret_key=os.environ["LANGFUSE_SECRET_KEY"],
    host="https://cloud.langfuse.com"
)

print("Langfuse client initialized successfully")

output

Langfuse client initialized successfully

Common variations

You can also set environment variables in Windows PowerShell or directly in your Python code (not recommended for production). Additionally, Langfuse supports custom hosts if you run a self-hosted instance.

bash

# Windows PowerShell
$env:LANGFUSE_PUBLIC_KEY = "your_public_key_here"
$env:LANGFUSE_SECRET_KEY = "your_secret_key_here"

# Python direct assignment (for testing only)
import os
os.environ["LANGFUSE_PUBLIC_KEY"] = "your_public_key_here"
os.environ["LANGFUSE_SECRET_KEY"] = "your_secret_key_here"

Troubleshooting

If you see authentication errors, verify that both LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY are correctly set and accessible in your environment.
Ensure no extra whitespace or quotes are included when exporting environment variables.
Check network connectivity to https://cloud.langfuse.com or your custom host.

✅

Key Takeaways

Always set both LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY environment variables for Langfuse SDK authentication.
Use os.environ in Python to access these keys securely without hardcoding.
For production, avoid setting keys directly in code; use environment variables or secret management.
Langfuse supports custom hosts via the host parameter during client initialization.
Verify environment variables carefully to prevent authentication or connectivity issues.

Verified 2026-04

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