Update main.tf

nodes/main.tf

-variable "image_compute" {default = "string"}
-variable "flavor" {default = "string"}
+variable "image_compute" {}
+variable "flavor" {}
 variable "compute_node_count" { }
-variable "internal_net" {default = "string"}
+variable "internal_net" {}
 variable "key_pair" {type = "string"}
 variable "internal_subnet_id" {type = string}