petri 0.23.2

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.

Install

Install using poetry poetry add petri or pip pip install petri.

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

Usage

• 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):
    class Config:
        env_prefix = "MY_PKG_"  # VERY IMPORTANT!!!
    # define common settings here

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)

Note

You must define Config.env_prefix inside your setting class (see above). This allows petri to select settings class using envvars.

As an example, a package named my-pkg should have its setting(s) classes:

1. Inherit from petri.BaseSettings

2. Contain a Config subclass (just like for pydantic’s), with its env_prefix set to "MY_PKG_".

The code used should be compatible with:

Config.env_prefix=[package_name].upper().replace('-' ,'_')+'_'.

(See petri.Petri.pkg_2_envvar.)

• [OPTIONAL] Define an environment variable named env_file, to feed

  additional envs. Its value must be the path to a valid, existing file.

• Select which of your settings classes to use, by doing one of the folowing:

  • Point the selector envvar (eg: for a-pkg, this would be A_PKG_CONFIG=a_pkg.settings:Production, see petri.Petri.pkg_2_envvar), or

  • Use the default_config kwarg when instantiating petri.Petri (See below)

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

Additional Info

• Load env_file’s contents, if defined.

• Provide your package’s metadata (version, author, etc), available in pkg.meta (lazy-loaded to avoid reading metadata files unnecessarily).

• Activate and instantiate a settings class, according to environment var and default, available in pkg.settings (https://pydantic-docs.helpmanual.io/#id5)

• Configure and expose a logger, available in pkg.log, which uses configuration defined in your settings.

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For more info, check the docs.