Flowlines SDK for Python — Integration Guide

Flowlines is an observability and memory SDK for LLM-powered Python applications. It instruments LLM provider APIs using OpenTelemetry, automatically capturing requests, responses, timing, and errors, and exports them to the Flowlines backend.

Step 1: Install the SDK

Requires Python 3.10+.

pip install flowlines

Then install instrumentation extras for the providers used in the project:

# Single provider
pip install "flowlines[openai]"

# Multiple providers
pip install "flowlines[openai,anthropic]"

# All supported providers
pip install "flowlines[all]"

Available extras: openai, anthropic, google-generativeai, bedrock, cohere, vertexai, together, groq, mistralai, ollama, replicate, transformers, sagemaker, watsonx, writer, alephalpha, voyageai, openai-agents, pinecone, chromadb, qdrant, lancedb, marqo, milvus, weaviate, langchain, llamaindex, crewai, agno, haystack, mcp.

Step 2: Initialize the SDK

CRITICAL: flowlines.init() MUST be called BEFORE creating any LLM client (e.g., OpenAI(), Anthropic()). If the client is created first, its calls will not be captured.

flowlines.init() must be called exactly once. A second call raises RuntimeError.

Mode A — No existing OpenTelemetry setup (default)

Use this when the project does NOT already have its own OpenTelemetry TracerProvider. This is the most common case.

import flowlines

flowlines.init(api_key="<FLOWLINES_API_KEY>")

This auto-detects installed LLM libraries, instruments them, and exports LLM-related spans to Flowlines.

Mode B — Existing OpenTelemetry setup

Use this only when the project already manages its own TracerProvider. Pass has_external_otel=True to prevent the SDK from creating a second one.

import flowlines
from opentelemetry.sdk.trace import TracerProvider

flowlines.init(api_key="<FLOWLINES_API_KEY>", has_external_otel=True)

provider = TracerProvider()

# Add the Flowlines span processor to the existing provider
processor = flowlines.create_span_processor()
provider.add_span_processor(processor)

# Instrument providers using the Flowlines instrumentor registry
for instrumentor in flowlines.get_instrumentors():
    instrumentor.instrument(tracer_provider=provider)

Init parameters

flowlines.init(
    api_key: str,                    # Required. The Flowlines API key.
    ingest_endpoint: str = "https://ingest.flowlines.ai",  # Ingest backend URL.
    api_endpoint: str = "https://api.flowlines.ai",  # API backend URL (memory, sessions).
    has_external_otel: bool = False,  # True if project has its own TracerProvider.
    verbose: bool = False,            # True to enable debug logging to stderr.
)

Step 3: Add context to LLM calls

Wrap LLM calls in flowlines.context() to tag spans with user/session/agent IDs:

with flowlines.context(user_id="user-42", session_id="sess-abc"):
    response = client.chat.completions.create(model="gpt-4", messages=messages)

user_id is required. session_id and agent_id are optional.

For cases where a context manager doesn't fit (e.g., across request boundaries in web frameworks), use the imperative API:

token = flowlines.set_context(user_id="user-42", session_id="sess-abc")
try:
    client.chat.completions.create(...)
finally:
    flowlines.clear_context(token)

Context does NOT auto-propagate to child threads/tasks. Set it explicitly in each thread or async task.

How to find values for user_id, session_id, and agent_id

Look for existing data in the codebase:
- user_id: the end-user making the request (e.g., authenticated user ID, email, API key owner)
- session_id: the conversation or session grouping multiple interactions (e.g., chat thread ID, conversation UUID)
- agent_id: the AI agent or assistant handling the request (e.g., agent name, assistant ID)

If obvious mappings exist, use them directly:

with flowlines.context(user_id=request.user.id, session_id=thread_id):
    ...

If mappings are unclear, ask the user which variables or fields should be used.

If no data is available yet, use placeholder values with TODO comments:

with flowlines.context(
    user_id="anonymous",  # TODO: replace with actual user identifier
    session_id=f"sess-{uuid.uuid4().hex[:8]}",  # TODO: replace with actual session/conversation ID
):
    ...

Step 4: Retrieve and inject memory

Retrieve what Flowlines remembers about a user from previous conversations:

memory = flowlines.get_memory("user-42", session_id="sess-abc")
# or with more context:
memory = flowlines.get_memory("user-42", session_id="sess-abc", agent_id="agent-1", view="summary")

For async code:

memory = await flowlines.aget_memory("user-42", session_id="sess-abc")

Both return a JSON string of the memory object, or None if no memory exists or if an error occurs.

Inject the memory into your prompt so the LLM can personalize its responses:

messages = [{"role": "system", "content": "You are a helpful assistant."}]
if memory:
    messages.append({
        "role": "system",
        "content": f"Here is what you know about this user from previous conversations:\n{memory}",
    })
messages.append({"role": "user", "content": user_input})

Step 5: End the session

When a conversation session is over, signal it to the backend. This flushes pending spans and notifies Flowlines:

flowlines.end_session("user-42", session_id="sess-abc")

For async code:

await flowlines.aend_session("user-42", session_id="sess-abc")

Look for places in the codebase where a session naturally ends:

An explicit "end conversation" or "close session" action
A WebSocket disconnect handler
A cleanup/logout handler
A timeout that expires inactive sessions

If the application has no concept of sessions (e.g., a single-shot CLI tool), skip this step.

Full example

import flowlines
from openai import OpenAI

flowlines.init(api_key="your-flowlines-api-key")
client = OpenAI()

user_id = "user-42"
session_id = "sess-abc"

# Retrieve memory for this user
memory = flowlines.get_memory(user_id)

messages = [{"role": "system", "content": "You are a helpful assistant."}]
if memory:
    messages.append({
        "role": "system",
        "content": f"Here is what you know about this user from previous conversations:\n{memory}",
    })
messages.append({"role": "user", "content": "Hello!"})

with flowlines.context(user_id=user_id, session_id=session_id):
    response = client.chat.completions.create(model="gpt-4", messages=messages)

flowlines.end_session(user_id=user_id, session_id=session_id)

Common mistakes to avoid

Do NOT create the LLM client before calling flowlines.init() — spans will be missed.
Do NOT call flowlines.init() more than once — it raises RuntimeError.
Do NOT forget to install the instrumentation extras for the providers you use (e.g., "flowlines[openai]").
Do NOT assume context propagates to child threads — set it explicitly in each thread/task.

Verifying trace ingestion

If the user provides a Flowlines API key, you can verify that traces are being received by the backend:

curl -X GET 'http://api.flowlines.ai/v1/get-traces' -H 'x-flowlines-api-key: <FLOWLINES_API_KEY>'

Use this after the integration is complete and the application has made at least one LLM call, to confirm that traces are flowing correctly.

integrate-flowlines-sdk-python