Langfuse

Langfuse is an open-source platform for LLM observability. It provides tracing and monitoring capabilities for AI applications, helping developers debug, analyze, and optimize their AI systems. Langfuse integrates with various tools and frameworks, including workflow builders and runtimes like SkillFlaw.

This guide explains how to configure SkillFlaw to collect tracing data about your flow executions and automatically send the data to Langfuse.

Prerequisites

• An account in a Langfuse Cloud or Langfuse self-hosted instance
• A running SkillFlaw server with a flow that you want to trace

tip

If you need a flow to test the Langfuse integration, see the SkillFlaw quickstart.

Set Langfuse credentials as environment variables

1. Create a set of Langfuse API keys.

2. Copy the following API key information:

   • Secret Key
   • Public Key
   • Host URL

3. Set your Langfuse project credentials as environment variables in the same environment where you run SkillFlaw.

   In the following examples, replace SECRET_KEY, PUBLIC_KEY, and HOST_URL with your API key details from Langfuse.

   Linux or macOS

   These commands set the environment variables in a Linux or macOS terminal session:

   
   

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   export LANGFUSE_SECRET_KEY=SECRET_KEY

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   export LANGFUSE_PUBLIC_KEY=PUBLIC_KEY

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   export LANGFUSE_HOST=HOST_URL

   
   

   Windows

   These commands set the environment variables in a Windows command prompt session:

   
   

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   set LANGFUSE_SECRET_KEY=SECRET_KEY

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   set LANGFUSE_PUBLIC_KEY=PUBLIC_KEY

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   set LANGFUSE_HOST=HOST_URL

   
   

Start SkillFlaw and view traces in Langfuse

1. Start SkillFlaw in the same environment where you set the Langfuse environment variables:

   
   

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   uv run skillflaw run

   
   

2. Run a flow.

   SkillFlaw automatically collects and sends tracing data about the flow execution to Langfuse.

3. View the collected data in your Langfuse dashboard.

   Langfuse also provides a public live trace example dashboard.

Disable Langfuse tracing

To disable the Langfuse integration, remove the Langfuse environment variables, and then restart SkillFlaw.

See also

• Langfuse GitHub repository