petri 0.24.1

Free your python code from 12-factor boilerplate.

petri: free your python code from 12-factor boilerplate.

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Summary

Importing petri equips your app/pacakage with:

• Dotenv file handling using python-dotenv.
• Package metadata (for installed packages), using importlib-metadata.
• Settings using pydantic.
• Logging config using structlog.
• Environment switching (prod/dev/test) handling via ENV environment variable.

Motivation

• In order to have same code for dev/production, it all starts with an innocent settings.py.
• In order to switch between them, it’s a good idea to use env vars…
• But sometimes, you want to overrride a single variable.
• But sometimes, you want to overrride several variables.
• Plus, colored logs while developing are pretty.
• Plus, structured logs in production look smart.

Features

• [X] Sane defaults for logging:
  • [X] json logs for production.
  • [X] user-friendly (spaced) + colored for development.
  • [X] Enforce root logger’s formatting.
• [X] Easy settings:
  • [X] Toggle between configurations using a signle env var.
  • [X] Define default configuration in case the env var is not present.
  • [X] Granular settings override using environment variables.
  • [X] Batch settings override by loading a .env.
• Read package metadata (author, version, etc):
  • [X] Lazy-loaded to avoid reading files during imports.
  • [X] For installed packages only.

Install

Install using poetry poetry add petri or pip pip install petri or (for dev) pip install git+https://github.com/pwoolvett/petri.

Optionally, also install the color extra for colored logs using colorama.

Usage

Just define configuration setting(s) and instantiate petri.Petri:

#  my_package/__init__.py

from petri import Petri
from petri.settings import BaseSettings
from petri.loggin import LogFormatter, LogLevel


class Settings(BaseSettings):
    SQL_CONNECTION_STRING = 'sqlite:///database.db'  # example setting

class Production(Settings):
    LOG_FORMAT = LogFormatter.JSON
    LOG_LEVEL = LogLevel.TRACE


class Development(Settings):
    LOG_FORMAT = LogFormatter.COLOR  # requires colorama
    LOG_LEVEL = LogLevel.WARNING


pkg = Petri(__file__)

# demo logs
pkg.log.info("log away info level",mode=pkg.settings, version=pkg.meta.version)
pkg.log.warning("this will show", kewl=True)

That’s it!. Watch the animation above for results running python -c “import my_package”

Optionally, define an environment variable named env_file, to override the settings:

• Its value must be the path to a valid, existing file.
• Its contents must have name=value pairs.
• The names must be of the form [MY_PACKAGE]_[SETTING_NAME] (Watch the animation above).

To select which of your settings classes to use, you can:

• Point the selector envvar (eg: for my-pkg, this would be MY_PKG_CONFIG=my_pkg.settings:Production), or
• Use the default_config kwarg when instantiating petri.Petri (eg: use pkg = Petri(__file__, default_config=”my_pkg.settings:Production”) in the example above).

Of course, you can use both. Petri will attempt to load the selecto envvar, and if not found, default to the defined kwarg.

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For more info, check the docs.