tf-maps-lookups.tf

# variables.tf
variable "env" {
  description = "env: stg or prod"
}

variable "image_name" {
  type        = "map"
  description = "Image for container."
  default     = {
    dev  = "occollector:latest"
    prod = "occollector:ubuntu"
  }
}

# main.tf
resource "docker_image" "image_id" {
  name = lookup(var.image_name, var.env)
}

# run it!
# terraform plan -out=tfstg_plan -var env=stg
# terraform plan -out=tfprod_plan -var env=prod