Set the name tag of an AWS instance from the AWS instance (e.g., in userdata)

nametag.sh

# terraform locals (in a .tf file)
locals {
  name_prefix   = "terrafirm"
  full_build_id = format("notcb:%s", uuid())                                                                                                                            #128-bit rfc 4122 v4 UUID
  build_id      = "${substr(element(split(":",local.full_build_id),1), 0, 8)}${substr(element(split(":",local.full_build_id),1), 9, 4)}"
  resource_name = "${local.name_prefix}-${local.build_id}"
}
  
# terraform template declaration (in a .tf file)
data "template_file" "lx_userdata" {
  template = "${file("linux/userdata.sh")}"

  vars {
    tfi_name_tag        = "${local.resource_name}"
  }
}

# userdata.sh file
#!/bin/bash
aws ec2 create-tags --resources $(curl -s http://169.254.169.254/latest/meta-data/instance-id) --tags Key=Name,Value="${tfi_name_tag}"