Add seperate ood image var

vars.tf

 variable "admin-state-up" {
   description = "whether admin state in enabled. defualt is true"
-  default = true
+  default     = true
 }
 
 variable "enable-dhcp" {
   description = "whether dhcp in enabled. defualt is true"
-  default = true
+  default     = true
 }
 
 variable "external-net" {
@@ -33,14 +33,18 @@ variable "internal-subnet" {
   default = "clustersubnet"
 }
 
-variable "image" {
+variable "image_ohpc" {
+  default = "CentOS-7-x86_64-GenericCloud-1905"
+}
+
+variable "image_ood" {
   default = "CentOS-7-x86_64-GenericCloud-1905"
 }
 
 variable "keypair-name" {
   default = "os-gen-keypair"
 }
-  
+
 variable "ohpc-instance-name" {
   default = "ohpc"
 }
@@ -67,10 +71,10 @@ variable "router" {
 
 variable "ssh-private-key" {
   description = "Path to file containing private key"
-  default =  "~/.ssh/id_rsa"
+  default     = "~/.ssh/id_rsa"
 }
 
 variable "ssh-public-key" {
   description = "Path to file containing public key"
-  default = "~/.ssh/id_rsa.pub"
-}
\ No newline at end of file
+  default     = "~/.ssh/id_rsa.pub"
+}