logbrew-fastapi 0.1.2

FastAPI integration for capturing LogBrew request spans and exceptions.

logbrew-fastapi

FastAPI integration for capturing LogBrew request spans and exceptions with the public Python SDK.

Install

python3 -m pip install logbrew-sdk logbrew-fastapi

The package is typed, ships py.typed, depends on the core logbrew-sdk, and keeps FastAPI as a normal framework dependency instead of bundling or monkeypatching the user's app.

Example

from fastapi import FastAPI
from logbrew_fastapi import add_logbrew_middleware
from logbrew_sdk import LogBrewClient, RecordingTransport

client = LogBrewClient.create(
    api_key="LOGBREW_API_KEY",
    sdk_name="logbrew-fastapi",
    sdk_version="0.1.0",
)
transport = RecordingTransport.always_accept()
app = FastAPI()
add_logbrew_middleware(
    app,
    client=client,
    transport=transport,
    span_id_factory=lambda: "b7ad6b7169203331",
)


@app.get("/health")
def health() -> dict[str, bool]:
    return {"ok": True}

add_logbrew_middleware() records successful requests as span events, records unhandled handler exceptions as issue plus error-span events, and flushes through the provided transport after each response. If no transport is provided, events stay queued on the core client so the app can flush them itself.

When an incoming request has a valid W3C traceparent header, request capture continues that trace by using the incoming traceId and parent span id while creating a fresh child span id. Missing or malformed traceparent headers keep the existing synthetic request span behavior so bad client headers do not break the app. Automatic metadata uses the request path without query text.

Request duration metrics are opt-in. Set capture_request_metrics=True to emit an explicit http.server.duration histogram for completed requests:

add_logbrew_middleware(
    app,
    client=client,
    transport=transport,
    capture_request_metrics=True,
)

The metric includes primitive, low-cardinality metadata: framework, method, routeTemplate, statusCode, and statusCodeClass. Query strings and URL hashes are omitted. Set capture_successful_requests=False with capture_request_metrics=True when you only want duration metrics and not successful request spans. Avoid user IDs, request payloads, headers, or free-form text in custom metric metadata.

By default, transport failures do not break the FastAPI response path. Set raise_flush_errors=True only when your app wants delivery failures to surface as request errors.

Use a clearly fake placeholder like LOGBREW_API_KEY in examples.