2 min read | by Jordi Prats
To be able to conditionally append objects (or strings) to a list in terraform we must put it in another way: How do we dynamically generate a list of objects?
The answer is using we can use the concat() function
result = concat(["A"], ["B"]) The concat() function will merge any set of lists. The trick here is to conditionally merge empty lists if needed to get the list we want, for example:
conditional_append = concat(var.set_a ? ["A"]:[], var.set_b ? ["A"]:[]) Using this code if we set:
set_a = false set_b = false We will get an empty array:
~ conditional_append = [] By setting one of them to true:
set_a = true set_b = false The resulting list will have just one item:
~ conditional_append = [ + "A", ] Finally, by setting both to true:
set_a = true set_b = true We will be getting both strings on a list as expected:
~ conditional_append = [ + "A", + "B", ] Posted on 24/12/2020