langfuse_sdk_tracing_spans_generations_quickstart.py

1from langfuse import Langfuse
2import os
3
4# Initialize the Langfuse client
5# Credentials can be found in the Langfuse Project Settings
6langfuse = Langfuse(
7    public_key="pk-lf-...",
8    secret_key="sk-lf-...",
9    host="https://cloud.langfuse.com" # or your self-hosted URL
10)
11
12# 1. Create a trace
13trace = langfuse.trace(
14    name="capital-city-query",
15    user_id="user-123",
16    metadata={"env": "production"}
17)
18
19# 2. Add a span (represents a step in the process)
20span = trace.span(
21    name="search-database",
22    input={"query": "What is the capital of France?"}
23)
24
25# 3. Log a generation (the actual LLM call)
26generation = span.generation(
27    name="openai-completion",
28    model="gpt-3.5-turbo",
29    input=[{"role": "user", "content": "What is the capital of France?"}],
30    model_parameters={"temperature": 0.7}
31)
32
33# ... (Execute LLM call) ...
34output_text = "The capital of France is Paris."
35
36# 4. Update the generation with the output
37generation.end(output=output_text)
38
39# 5. End the span
40span.end(output=output_text)
41
42# 6. Finalize the trace
43trace.end()
44
45# Optional: Flush the SDK to ensure all events are sent before exiting
46langfuse.flush()