Imperative config means you run the code and it does what the code says. Declarative means “some system reads and parses the config, can do clever things to ch

Imperative config means you run the code and it does what the code says. Declarative means “some system reads and parses the config, can do clever things to change what happens in different circumstances, show you a preview of what happens, track chances of what the config has been in a straightforward way, audit the config for consistency across several systems or for adherence to selected principles, and do other smart things”. These are possible because the config is a data structure now. You can do things with a data structure you can’t do with a shell script. The script is too opaque and our computers are not yet smart enough to analyze it in these ways. There are great advantages to the simplicity of imperative configuration scripts, which is why shell scripts will not soon die. There is some peril (shell scripting in particular is full of tricksy traps; alternative languages may mitigate this.) There is great power and some peril in imperative config. It’s a choice.