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We get a flat ~800$ for an on call week (Thursday to Thursday) and Friday is off. Nothing extra for working night, but you’re not expected to work a full day if you had an incident the night before.
For larger environments infrastructure drift is a much bigger headache then that Terraform has to store a json blob somewhere.
Having a combination of state and reading running state (like Terraform does) is crucial to have a tool that can scale for large environments.