structlog
Structured logging library for Python that makes logging output consistent, processable, and observable. Provides a processor pipeline for enriching log events (timestamp, request ID, user context), supports JSON output for log aggregation, context management via bound loggers, and async support. More powerful than loguru for complex structured logging needs in production services.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
MIT licensed. Structured logging — avoid including sensitive data in log events. Use custom processors to redact sensitive fields.
⚡ Reliability
Best When
You're building a production Python service where consistent structured JSON logging with context binding and custom processor pipelines matters for observability.
Avoid When
You want simple, beautiful logging with minimal configuration — use loguru instead. Structlog's power comes with configuration complexity.
Use Cases
- • Add consistent structured JSON logging to Python agent services with automatic context propagation
- • Bind request-scoped metadata (request_id, user_id, trace_id) to agent loggers for correlated logging
- • Build processor pipelines that enrich all log events with service metadata before JSON output
- • Integrate with Python stdlib logging to capture third-party library logs in structured format
- • Implement OpenTelemetry-compatible trace context injection into log events for distributed tracing
Not For
- • Simple logging for scripts — Python's stdlib logging or loguru is simpler for basic use cases
- • Applications where developer experience matters more than structure — loguru has a much simpler API
- • Projects avoiding configuration complexity — structlog requires explicit processor configuration for production setup
Interface
Authentication
Local library — no authentication required. MIT licensed.
Pricing
MIT licensed. Zero cost.
Agent Metadata
Known Gotchas
- ⚠ Must configure structlog before use — structlog.configure(processors=[...]) sets global pipeline; do this once at app startup before any logging
- ⚠ Bound loggers: log = structlog.get_logger().bind(request_id='123') creates logger with bound context — all subsequent log calls include request_id automatically
- ⚠ Async support: use structlog.stdlib.AsyncBoundLogger or structlog.contextvars for asyncio context propagation — standard bound loggers aren't async-context-aware
- ⚠ Stdlib integration: structlog.stdlib.add_log_level, add_logger_name processors bridge to Python's logging module — needed to capture third-party library logs
- ⚠ Development vs production config differs significantly — dev: ConsoleRenderer with colors; prod: JSONRenderer with timestamps and structured fields
- ⚠ structlog.contextvars.bind_contextvars(request_id=req_id) for request-scoped context in async code — automatically cleared per contextvars context
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for structlog.
Scores are editorial opinions as of 2026-03-06.