kubernetes_provision_vars = <<EOF
vsphere_user: "${var.vsphere_user}"
vsphere_password: "${var.vsphere_password}"
vsphere_host: "${var.vsphere_server}"
EOF


...


locals {
  ansible = "ansible-playbook -i ${var.inventory} ${(var.vars_file == "") ? "" : "-e @${var.vars_file}"}"
  vars_hash = "${sha512(var.vars)}"
}

resource "null_resource" "vars_file" {
  triggers = {
    content_hash = "${local.vars_hash}"
  }

  count = "${var.vars == "" ? 0 : 1}"

  provisioner "local-exec" {
    command = <<COMMAND
cat <<EOF > ${var.vars_file}
${var.vars}
${var.volatile_vars}
EOF
COMMAND
  }
}

resource "null_resource" "playbook" {
  triggers = {
    serial = "${var.serial}"
  }

  provisioner "local-exec" {
    command = "${local.ansible} -u ${var.vsphere_virtual_machine_template_user} -D ${var.provision_root}/${var.name}.yaml"
  }
}