How to restrict a module/service from executing in terraform - terraform

Question

I have multiple environments which gets provisioned using terraform. my question how to restrict a particular module from executing on a particular environment.
Eg: I need to deploy a instance service and associated module only in production, but not to lower environments
I have the below structure with services and each service calls modules.
structure:
├── instances
│   ├── config.tfplan
│   ├── data.tf
│   ├── main.tf
│   └── variables.tf
├── modules
│   ├── buckets
│   │   ├── buckets.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   ├── compartments
│   │   ├── compartments.tf
│   │   ├── output.tf
│   │   └── variables.tf
│   ├── iam
│   │   ├── groups.tf
│   │   ├── outputs.tf
│   │   ├── policies.tf
│   │   ├── users.tf
│   │   └── variables.tf
│   ├── instances
│   │   ├── instance.tf
│   │   ├── output.tf
│   │   └── variables.tf

Answer 1

This was not possible in older versions of Terraform but with version 0.12.6. You can add for_each in the module. Please find here an example of how I am using for_each:
Define variable:
variable "cloudwatch_event" {
description = "Map of cloudwatch event configuration"
type = map(any)
default = {
default = {}
}
}
Define resource:
module "cloudwatch_event" {
source = "git::git#github.com:tomarv2/terraform-aws-cloudwatch-event.git?ref=v0.0.4"
for_each = var.cloudwatch_event
description = lookup(each.value, "description", null)
custom_input = lookup(each.value, "custom_input", null)
suffix = lookup(each.value, "suffix", "rule")
schedule = lookup(each.value, "schedule", null)
deploy_event_rule = var.deploy_cloudwatch_event_trigger
deploy_event_target = var.deploy_cloudwatch_event_trigger
target_arn = join("", aws_lambda_function.lambda.*.arn)
#-----------------------------------------------
# Note: Do not change teamid and prjid once set.
teamid = var.teamid
prjid = var.prjid
}
As you can see if there is no cloudwatch_event this resource will not get deployed.
Please check the module repo located here: https://github.com/tomarv2/terraform-aws-lambda
Terraform documentation for your reference: https://www.terraform.io/docs/language/meta-arguments/for_each.html