I'm not sure why choosing a configuration file format like ini or yaml prevent configuration validation. This logic can be expressed within the program itself:

I'm not sure why choosing a configuration file format like ini or yaml prevent configuration validation. This logic can be expressed within the program itself: parse the file, and validate inside the program that the configuration is consistent. Also putting the validation logic directly inside the configuration file is not a good idea in my opinion for two main reasons: * the validation logic is then "external" to the program and can be overridden (with potential catastrophic effects) by the operator installing the program. * Configuration validation logic can be quite complex, and having it inside the configuration file would clutter it too much in many cases. I tend to see configuration files as an API/Interface (maybe because I'm an SRE), and as any interface, I want it clearly defined, with known boundaries and as explicit as possible. For these reasons I'm not a big fan of using a fully fledge programing language as configuration.