Chapter 5: Terraform tips and tricks

• count
  • usage:

    resource "blablabla" "blablabla_name" {
    count = 3
    name  = "bla${count.index}"
    }

  • result: 3 elements ([0],[1],[2]) → resources array
  • with length():

    variable "bla_names" {
      type    = list(string)
      default = ["bla_green","bla_yellow","bla_red"] 
    }
    resource "blablabla" "blablabla_name" {
      count = length(var.bla_names)
      name  = bla_names[count.index]
    }

  • output
    • [#]: use cardinal to access a concrete element
    • [*]: all elements from resource list
  • each element is assigned to their index in state, deletes o modifications implies «move» all elements after that.
  • only usable for resources, no inline blocks
• for_each
  • lists (using toset() function), sets and maps
  • for use in resources o inline blocks
  • use each.key and each.value
  • usage:

    variable "bla_names" {
      type    = list(string)
      default = ["bla_green","bla_yellow","bla_red"] 
    }
    resource "blablabla" "blablabla_name" {
    for_each = toset(var.bla_names)
    name  = each.value
    }

variable "bla_names" {
  type    = map(string)
  default = {"green" = "bla_green","yellow" = "bla_yellow","red" = "bla_red"}
  #default = map("green","bla_green", "yellow","bla_yellow", "red","bla_red")
}
resource "blablabla" "blablabla_name" {
for_each = toset(var.bla_names)
name  = each.value
}

• output:
  • values(<resource_name>)[*].attribute
• for
• for string

variable "booleana" {
  type = bool
}
resource "resource" "resource_name" {
  count = var.booleana ? 1 : 0
  ...
}
variable "cadena" {
  type = string
  default = "aaa"
}
resource "resource" "resource_name {
  count = format("%.1s",var.cadena) == "a" ? 1 : 0
}