A plan for a load balancer contains the line +/- resource "aws_lb" "main", and the resource sets lifecycle { create_before_destroy = true }. A junior reviewer asks what this marker means for the running service. What is the correct explanation?

Terraform's plan output prefixes each resource with a symbol for the planned action: + for create, ~ for update in place, - for destroy, -/+ for destroy and then create replacement, and +/- for create replacement and then destroy. Replacement happens when a changed argument cannot be updated in place. By default Terraform destroys the old object first, which is the -/+ case; when the resource sets create_before_destroy in its lifecycle block, Terraform reverses the order, creates the new object, updates dependents, and then destroys the old one, which the plan shows as +/-. For a load balancer this keeps a working object in place throughout the swap, though clients may still need to follow the new object's address if it changes. An in-place update is shown with ~ and does not create a new object. Destroying first is the -/+ case, which is what create_before_destroy prevents here. The -replace option forces a replacement that would not otherwise be planned; a replacement already shown in the plan happens on apply without it. Exam caveat: create_before_destroy can fail when names must be unique, because both objects exist briefly, so name prefixes or generated names are often required. Operational check: read the plan line for the forces replacement annotation to learn which argument triggers it, and confirm dependents are updated to the new object.