Add Onacol

[JNevrly]

What is this Python project?

Onacol is a low-opinionated configuration management library with following features:

• YAML (=structured and hierarchical) configuration file support
• Environment variables support (explicit and implicit)
• CLI arguments support
• Configuration merging/overwriting/layering
• Parameter validation (via Cerberus)
• Configuration schema, documentation and default values are defined in single YAML -> No code schema.
• Minimal dependencies

What's the difference between this Python project and similar ones?

Comparing with all the configuration management libraries & frameworks I could find on GitHub, based on the features I consider important:

Framework	YAML	ENV vars	CLI args	Merging	Validation	No code schema
Hydra	✔️	✔️	❓	✔️	✔️	✖️
Pydantic	❓	❓	✔️	✔️	✔️	✖️
Dynaconf	✔️	❓	✔️	✔️	✔️	✖️
python-dotenv	✖️	✔️	✖️	✖️	✖️	✖️
Gin Config	❓	❓	❓	❓	✔️	✖️
Python Decouple	✖️	✖️	✔️	✔️	✖️	✖️
OmegaConf	✔️	✔️	✔️	✔️	✔️	✖️
Confuse	✔️	✔️	❓	✔️	✔️	✖️
Everett	✔️	✔️	✔️	❓	✔️	✖️
parse_it	✔️	✔️	✔️	✔️	❓	✖️
Grift	✖️	✖️	✖️	❓	✔️	✖️
profig	✖️	✔️	✖️	❓	✔️	✖️
tweak	✔️	✖️	✖️	✔️	✖️	✖️
Bison	✔️	❓	✔️	✔️	✔️	✖️
Config-Man	✖️	✔️	✔️	❓	✔️	✖️
figga	✔️	✖️	✔️	❓	✖️	✖️
Onacol	✔️	✔️	✔️	✔️	✔️	✔️

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