Terraform dynamic blocks dynamic generates repeated nested blocks from a variable - avoids copy-pasting the same block for each item. variable "ingress_rules" { default = [ { port = 80 , protocol = "tcp" , cidr = "0.0.0.0/0" }, { port = 443 , protocol = "tcp" , cidr = "0.0.0.0/0" }, { port = 22 , protocol = "tcp" , cidr = "10.0.0.0/8" }, ] } resource "aws_security_group" "web" { name = "web" dynamic "ingress" { for_each = var . ingress_rules content { from_port = ingress . value . port to_port = ingress . value . port protocol = ingress . value . protocol cidr_blocks = [ ingress . value . cidr ] } } } iterator name By default the iterator is the block label ( ingress above). Override it with iterator : dynamic "ingress" { for_each = var . ingress_rules iterator = rule content { from_port = rule . value . port to_port = rule . value . port protocol = rule . value .…