Count

You can add a count parameter to resouces, like this:

# A simplified example.
resource "azurerm_virtual_machine" "vm" {
  name     = "myTFVM-robert"
  count    = 3
  location = "west europe"
  vm_size  = "Standard_DS1_v2"
}

In the example above, the resource is created 3 times.

If you need to refer to one of the (three) instances, you can refer to:

# First instance
azurerm_virtual_machine.vm[0]
# Second instance
azurerm_virtual_machine.vm[1]
# Third instance
azurerm_virtual_machine.vm[2]

Likely the reference also has a count meta argument set, so you can use count.index, like this:

# A simplified example.
resource "azurerm_virtual_machine" "vm" {
  name     = "myTFVM-robert"
  count    = 3
  location = "west europe"
  vm_size  = "Standard_DS1_v2"
}

# A simplified counted resource example.
resource "azurerm_dns_a_record" "example" {
  name                = "instance-${count.index}"
  count               = length(azurerm_virtual_machine.vm.count)
  zone_name           = azurerm_dns_zone.example.name
  records             = ["10.0.180.17"]
}

In the example above, two tricks are used:

1. count = length(azurerm_virtual_machine.vm.count). This takes the count from azure_virtual_machine_vm. With this construction, you can specify count just once, and re-use it over and over again.
2. name = "instance-${count.index}". This ${count.index} increases by 1 each loop. Be aware, counting starts at 0.

Referencing a counted resource.

Imagine you have some resource with a count in it:

resource "azurerm_virtual_machine" "vm" {
  name     = "myTFVM-robert-${count.index}"
  count    = 3
  location = "west europe"
  vm_size  = "Standard_DS1_v2"
}

You would get these machines:

• myTFVM-robert-0
• myTFVM-robert-1
• myTFVM-robert-2

That resource creates id. Image you’d like to use that id in another resource

resource "example_does_not_exist" "example" {
  name     = "something"
  count    = length(azurerm_virtual_machine.vm.count)
  vm_ids      = azurerm_virtual_machine.vm[*].id
}

The above is called a splat expression.