Ask HN: Application configuration storage tools?

Developers seem to commonly store configuration variables (API keys for third party, URLs to internal services, secrets, etc.) in source code or a .env file.

This leads to the following issues:

1. The same config gets duplicated across the codebase. 2. Config values cannot be quickly changed as needed. 3. If pushed to GitHub, improper user permissions could lead to unintentional access to the config.

Hashicorp Vault seems promising but looks to be pretty heavyweight. Is there a lighter weight alternative, either hosted or on-prem?