Everett - Configuration Library

3.5.0 · deprecated · verified Sat Apr 11

Everett is a Python configuration library for applications, offering flexible configuration management from various sources including process environment variables, .env files, dictionaries, INI files, and YAML files. It aims to provide clear error messages and support for automated documentation of configuration. As of October 15, 2025, the project is deprecated. The current version is 3.5.0, with prior releases indicating an active development cycle before deprecation.

Warnings

breaking The Everett project is officially deprecated as of October 15, 2025. It is no longer actively maintained or recommended for new projects. Existing users should consider migrating to alternative configuration libraries.
Fix: For new projects, choose an alternative configuration library. For existing projects, plan for migration away from Everett to a maintained library.
gotcha Support for INI and YAML configuration files requires installing extra dependencies. Using 'everett[ini]' for INI files or 'everett[yaml]' for YAML files is necessary; without them, attempts to use these configuration environments will fail.
Fix: Install Everett with the appropriate extra: `pip install 'everett[ini]'` or `pip install 'everett[yaml]'` depending on your needs.
gotcha When defining configuration in a class using `Option`, remember to specify a `parser` if the value is not a string (e.g., `bool`, `int`, `list`). If omitted, values will be treated as strings, which can lead to runtime type errors.
Fix: Always explicitly define a `parser` for `Option`s that are expected to be non-string types, e.g., `Option(parser=int, ...)` or `Option(parser=bool, ...)`.

Install

pip install everett Base installation
pip install 'everett[ini]' With INI file support
pip install 'everett[yaml]' With YAML file support

Imports

ConfigManager
```
from everett.manager import ConfigManager
```
The primary class for managing configuration.
Option
```
from everett.manager import Option
```
Used when defining configuration options within a class-based structure.

Quickstart

This quickstart demonstrates how to initialize a basic `ConfigManager` which automatically looks for configuration in environment variables. It retrieves 'host' and 'port' with specified defaults and a type parser for 'port'. The `doc` parameter provides helpful context for users encountering configuration errors.

import os
from everett.manager import ConfigManager

# Simulate environment variable for demonstration
os.environ['APP_HOST'] = '127.0.0.1'
os.environ['APP_PORT'] = '8080'

config = ConfigManager.basic_config(
    doc="Check https://example.com/configuration for documentation."
)

host = config('host', default='localhost')
port = config('port', parser=int, default='5000')

print(f"Application Host: {host}")
print(f"Application Port: {port}")

# Clean up simulated environment variable
del os.environ['APP_HOST']
del os.environ['APP_PORT']

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