CFEngine works by defining a desired state for a given context and converging towards that goal. Given there is no fixed starting point and that the current context might change wildly it can be challenging to succinctly answer the question “What would CFEngine do?”. In Feature Friday: Don’t fix, just warn we saw how an individual promise could be made to warn instead of trying to automatically converge towards the desired state, a granular --dry-run mode.

Implicit list iteration in CFEngine is quite a unique and novel feature. Today we look at a practice example showing how lists can improve the readability and maintainability of your policy. A novel feature in CFEngine is how a list variable is iterated when referenced as a scalar ($(variable)). Let’s take a look at a contrived example.