quartz/content/notes/Terraform.md

title	date	tags
Terraform	2024-12-23	cloud data IaC

What is it

• Infrastructure as Code (IaC)
• Manage Infrastructure (usually on Cloud) with configuration files rather than through UI
• Advantages:
  • Versionable
  • Repeatable and Reusable (easy to create dev, test, Prod envs by using same files)
  • Consistent (You know where to find active instances and where to drop them)
• Declarative Language
• Steps:
  • Scope: Identify the Infrastructures (individual unit of services, e.g. Compute Instance, VPN, etc)
  • Author: Write the configuration
  • Initialize: Install the plugins needed by Terraform
  • Plan: Preview the Changes Terraform will make to match your configurations
  • Apply: Make the planned changes

Build - The Blocks

• terraform: list the needed providers
  • backend: where to store the state file. Local by default.
• provider: initializes each provider
• resource: List all the resources.
  • Double entry name (uniqueness): resource name + personal identifier
  • You can then refer a resource into another resource (e.g. line 32 network = google_compute_network.vpc_network.name)

terraform {
  required_providers {
    google = {
	  source = "hashicorp/google"
	  version = "6.14.1"
	}
  }
  backend "gcs" {
    bucket = "anselboero-website-dev-tfstate"
  }
}

provider "google" {
  project = var.project
  region = var.region
  zone = var.zone
} 

resource "google_compute_network" "vpc_network" {
  name = "terraform-network"
}

resource "google_compute_instance" "my_vm_instance" {
  name = "terraform-instance"
  machine_type = "f1-micro"
  tags = ["web", "dev"]

  boot_disk {
    initialize_params {
      image = "cos-cloud/cos-stable"
	}
  }

  network_interface {
	network = google_compute_network.vpc_network.name
	access_config {
	}
  }
}

• Initialize the variables (any file .tf will be read by terraform):
  • Empty { } will ask you to insert a value during terraform apply

variable "project" { }
variable "region" {
  default = "us-central1"
}
variable "zone" {
  default = "us-central1-c"
}

Main Commands

• terraform init: when you initialize a new configuration
• terraform apply: create the infrastructure: will also apply changes in case you update the files. Two types of changes: - Non destructive: the resource will just be updated (e.g. adding a tag to a VM) - Destructive: The old resource will be destroyed first and a new one will be created (e.g. changing image to a VM)
• terraform destroy: Delete all the resources.

Open Questions

• I think it's not possible to save every single resource as a Tf object: For Example, how can you deploy the first resources without having initialized a Google Build Trigger via UI?
• How to structure the project?

Resources

• https://developer.hashicorp.com/terraform/tutorials/gcp-get-started (all the 7 Tutorials) (opened on 2024-12-23)
• Google Cloud Documentation