My First Terraform Module

Terraform module to create Pub/Sub notifications for Google Cloud Storage.

Photo by SpaceX on Unsplash

Introduction

I have been working on Terraform for last one year. In couple of projects we had a requirement to “establish a flow of event notification from Google Cloud Storage to a Cloud Pub/Sub.”

As part of creating this flow, we need to:

• Create a Google Cloud Storage bucket
• Create a Cloud Pub/Sub topic
• In order to enable notification, a special cloud storage service account unique to each project must have the IAM permission “roles/pubsub.publisher”.
• Create notification configured for a bucket for multiple trigger events.

Same code we had to copy and paste in several places with change in bucket_name, topic_name and trigger_event.

With Terraform, you can put your code inside of a Terraform module and reuse that module in multiple places throughout your code. Instead of having the same code copy/pasted in the staging and production environments, you’ll be able to have both environments reuse code from the same module.

Benefits of Modules

• Organize configuration
• Encapsulate configuration
• Re-use configuration
• Provide consistency
• Ensure best practices

My Module: terraform-google-storage-pubsub

https://registry.terraform.io/modules/vikramshinde12/storage-pubsub/google/latest

This module creates following resources:

1. Bucket : A Source bucket
2. Topic : The topic in Pub/Sub that receives notifications.
3. Event : The events that trigger a notification to be sent. e.g. OBJECT_FINALIZE (default) — New object is successfully created in the bucket. OBJECT_DELETE — an object has been successfully deleted.
4. Subscriber: Sample pull subscriber named “echo”.

Input Variables

1. bucket_name: Source bucket name on which Pub/Sub notification is configured.
2. topic_name: The topic in Pub/Sub that receives notifications.
3. event_type (optional): Trigger event type e.g. OBJECT_FINALIZE, OBJECT_DELETE, OBJECT_ARCHIVE.
4. project_id: Project Id

Output Variables

1. bucket_url: The Bucket Link URL
2. topic_name: The URI of the Pub/Sub Topic.

Example usage

Following is the simple code how to call the module in Terraform configurations.

resource "google_project_service" "pubsub_api" {
  project = "sample_project_id"
  service = "pubsub.googleapis.com"
}
module "gcs-pubsub" {
  source      = "vikramshinde12/storage-pubsub/google"
  version     = 1.0.1
  topic_name  = "sample_topic"
  bucket_name = "sample_bucket"
  project_id  = "sample_project_id"
  depends_on  = [google_project_service.pubsub_api]
}

Conclusion

This way I created a simple Terraform module in a the Terraform Registry as per minimal recommendation from Terraform. The Terraform Registry is integrated directly into Terraform to make it easy to use providers and modules.

Reference

Creating Modules - Terraform by HashiCorp

vikramshinde12/terraform-google-storage-pubsub

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