pfly 0.1.0

pfly - Python LOggling Linter

A Python logging linter that enforces best practices

Why?

Production incidents are harder to debug when:

• Exception logs lack stack traces (exc_info=True)
• Hot loops spam logs, degrading performance
• Inconsistent logging causes time delay in parsing logs
• Complementary: Use with structlog, loguru — not instead of them

Installation

uv pip install plly

Usage

plly path/to/code

plly path/to/code --config=plly.yml

Policies

Code	Policy	Description
LY001	exception_exc_info	Enforces exc_info=True in exception handlers to capture stack traces
LY002	log_loop	Prevents unconditional logging in hot loops (allows conditional logging)

Configuration

Create a plly.yml:

logger_names: [logger, logging, log]

exception_exc_info:
  levels: [error]
  severity: fail

log_loop:
  levels: [info, debug]
  severity: fail

Examples

LY001: Missing exc_info=True

# Fail
try:
    connect_db()
except Exception:
    logger.error("Connection failed")  # No stack trace!

# Pass
try:
    connect_db()
except Exception:
    logger.error("Connection failed", exc_info=True)

LY002: Logging in hot loops

# Fail
for user in users:
    logger.info(f"Processing {user}")  # Logs every iteration

# Pass
for i, user in enumerate(users):
    if i % 100 == 0:
        logger.info(f"Progress: {i}/{len(users)}")  # Conditional logging

License

Apache