Dynamically changing the resource name

Terraform
1

i am using terraform 0.12 version and i am creating multiple instances on the vmware cloud but i would like to differentiate between my instance via resource name.

something like we do in packer name= “vm-name{timestamp}” to make the names different from each other.

2

How are you creating multiple instances? If they are as separate resource blocks, then you can just name them separately.

If you are using for_each, then the each.key will be the name…

locals {
  collection = {
    first = 1
    second = 2
  }
}
resource "some_resource" "collection" {
  for_each = local.collection
}

will produce:

some_resource.collection["first"]
some_resource.collection["second"]

A more concrete example:

locals {
  dashboards = {
    "ASG-Overview" = {
      file = "ec2-asg-cloudwatch-dashboard.json.template"
      template_parameters = {
        vertical_annotations = file(format("clusters/%s/%s/annotations.json", var.cluster, var.environment))
        asgs                 = [for v in local.asgs : v if v.max_instances > 0]
      }
    }
    "Payments-Overview" = {
      file = "payments-cloudwatch-dashboard.json"
    }
    "Email-Overview" = {
      file = "ses-cloudwatch-dashboard.json"
    }
  }
}

resource "aws_cloudwatch_dashboard" "dashboards" {
  for_each = local.dashboards

  dashboard_name = each.key
  dashboard_body = contains(keys(each.value), "template_parameters") ? templatefile(each.value.file, each.value.template_parameters) : file(each.value.file)
}

produces:

aws_cloudwatch_dashboard.dashboards["ASG-Overview"]
aws_cloudwatch_dashboard.dashboards["Payments-Overview"]
aws_cloudwatch_dashboard.dashboards["Email-Overview"]

You can also use count and that will create multiple resources with the index being the “name” part …

some_resource.collection["0"]
some_resource.collection["1"]

I’ve had issues with this if the set is edited in some way or refers to locals and you’re using the count.index … things get destroyed/recreated because of the change in the index position.