logician 0.0.0.dev3

Fully typed, simple, intuitive, sensible and pragmatic logger configurator for standard python logging.

logician

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Fully typed, simple, intuitive, and pragmatic logger configurator for standard Python logging.

logician is a lightweight utility that simplifies configuring Python's built-in logging module. It supports logger setup using environment variables, CLI flags (-v, -q), and sensible defaults—all fully typed, tested, and documented.

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🚀 Features

• 🔧 Minimal boilerplate for structured logging
• 🌐 Environment-variable driven configuration (e.g. VT_ALL_LOG=DEBUG)
• ⚙️ Verbosity-aware: -v, -vv, -q, etc.
• 🎛️ Different formats for different log levels
• 🔌 Works seamlessly with standard loggers and any logger name used by 3rd-party libraries (e.g., "uvicorn", "sqlalchemy") — assuming those libraries use standard Python logging
• 🧪 Fully type annotated and well-tested via doctests
• 📚 Extensive docstrings with live examples

⚠️ Note: logician assumes that external libraries like uvicorn and sqlalchemy use Python's standard logging module. If a library uses a custom or non-standard logging system, logician may not affect it.

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📦 Installation

pip install logician

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🧰 Quick Start

from logician import configure

configure()

import logging
logger = logging.getLogger(__name__)
logger.info("Hello from logician!")

This sets up the root logger and all loggers derived from it with a sensible default formatter and log level.

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🔄 Environment Variable Configuration

logician reads log levels from environment variables like:

LGCN_ALL_LOG=DEBUG
LGCN_SOME_MODULE_LOG=WARNING

These automatically control the logger levels without code changes.

You can change the prefix (default is LGCN_) via env_prefix:

configure(env_prefix="APP_")

You can also use the lower-level API directly:

from logician.std_log.configurator import StdLoggerConfigurator
from logician.configurators.env import LgcnEnvListLC
import logging

logger = logging.getLogger('ap-generator')
logger = LgcnEnvListLC(["APGEN"], StdLoggerConfigurator(level=logging.INFO)).configure(logger)

See LgcnEnvListLC in logician.configurators.env to learn more.

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🗣️ CLI Verbosity Integration

Use -v, -vv, -q, --quiet flags from your CLI parser to dynamically set log levels:

from argparse import ArgumentParser
from logician.std_log.configurator import StdLoggerConfigurator, VQSepLoggerConfigurator
import logging

parser = ArgumentParser()
parser.add_argument("-v", "--verbose", action="count", default=0)
parser.add_argument("-q", "--quiet", action="count", default=0)
args = parser.parse_args()

lc = VQSepLoggerConfigurator(StdLoggerConfigurator(), verbosity=args.verbose, quietness=args.quiet)
logger = logging.getLogger(__name__)
logger = lc.configure(logger)

This configures the logger to reflect the verbosity or quietness of the CLI input.

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🪄 Log Formatting by Log Level

Many-a-times it is the case that more refined (lower) log-levels need to output more (detailed) information. Hence, logician maps more-detailed log-formats to lower log-levels. Different log levels can be mapped to different log formats automatically which takes effects thoughout all log levels.

⚠️ These format mappings currently assume use with Python's standard logging module. In the future, support may expand to other logging libraries or frameworks.

The default setup looks like this:

WARN and up -> '%(levelname)s: %(message)s'
INFO -> '%(name)s: %(levelname)s: %(message)s'
DEBUG -> '%(name)s: %(levelname)s: [%(filename)s - %(funcName)10s() ]: %(message)s'
TRACE and lower -> '%(asctime)s: %(name)s: %(levelname)s: [%(filename)s:%(lineno)d - %(funcName)10s() ]: %(message)s'

You can override these or pass in your own formatting configuration.

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🛠️ Advanced Configuration

from logician import configure

configure(
    logger_names=["sqlalchemy", "uvicorn"],
    level="INFO",
    env_prefix="MYAPP_",
    verbosity=1
)

Keyword Arguments

Param	Type	Description
logger_names	list[str]	Additional logger names to configure aside from root
level	str / int	Default log level (e.g., "INFO", 20)
verbosity	int	Verbosity count to decrease log level (-v)
quietness	int	Quietness count to increase log level (-q)
env_prefix	str	Prefix for reading env-based logger overrides

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🧪 Example Doctest

All public APIs include doctests. Example:

>>> from logician import derive_level
>>> derive_level(base="INFO", verbosity=1)
10
>>> derive_level(base="INFO", verbosity=0, quietness=1)
30

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🛠 Real-World Usage

FastAPI + Uvicorn + Environment config

from logician import configure
configure(logger_names=["uvicorn", "sqlalchemy"], env_prefix="API_")

CLI Tools

from vt.utils.logging import VQSepLoggerConfigurator, StdLoggerConfigurator
import logging

lc = VQSepLoggerConfigurator(StdLoggerConfigurator(), verbosity=args.verbose, quietness=args.quiet)
logger = logging.getLogger("my_tool")
logger = lc.configure(logger)

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🧪 Testing & Typing

• ✅ 100% typed (compatible with MyPy & Pyright)
• ✅ Doctests validate examples
• ✅ Poetry-managed project with tests in tests/

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📃 License

Apache License 2.0. See LICENSE for full text.

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🤝 Contributing

Contributions welcome!

git clone https://github.com/Vaastav-Technologies/py-logger.git
cd py-logger
poetry install
pytest

Please write tests and add doctests for public functions.

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🔗 Links

• 📦 PyPI: https://pypi.org/project/logician
• 🐙 GitHub: https://github.com/Vaastav-Technologies/py-logger