Using Terraform to Auto Scale and Load Balance Compute Engine Instances in GCP

From Google Cloud navigation, choose Compute Engine > VM instances.

Click SSH next to terraform-instance.

Use root privileges:

sudo -i

Change into the root directory:

cd /

Input the path to communicate with Terraform into the /etc/profile file:

echo "PATH='$PATH:/downloads/'" >> /etc/profile

Run the following in order to be able to call Terraform:

source /etc/profile

Call Terraform:

terraform

Allow the SDK to communicate with GCP:

gcloud auth login

Enter Y at the prompt.

Click on the link in the output.

Select the Cloud Student account.

Click Allow.

Copy the code provided.

Paste the code into the terminal.

Create the service account key:

gcloud iam service-accounts keys create /downloads/auto-scaling.json --iam-account <SERVICE_ACCOUNT_EMAIL>

Create a main.tf file:

vim main.tf

Paste in the following, replacing all instances of <PROJECT_NAME> with your project name, which can be found in the top navigation bar of the Google Cloud console:

provider "google" {
  version = "3.20.0"

  credentials = file("/downloads/auto-scaling.json")

  project = "<PROJECT_NAME>"
  region  = "us-central1"
  zone    = "us-central1-c"
}

resource "google_compute_network" "vpc_network" {
  name = "new-terraform-network"
}
resource "google_compute_autoscaler" "foobar" {
  name   = "my-autoscaler"
  project = "<PROJECT_NAME>"
  zone   = "us-central1-c"
  target = google_compute_instance_group_manager.foobar.self_link

  autoscaling_policy {
    max_replicas    = 5
    min_replicas    = 2
    cooldown_period = 60

    cpu_utilization {
      target = 0.5
    }
  }
}

resource "google_compute_instance_template" "foobar" {
  name           = "my-instance-template"
  machine_type   = "n1-standard-1"
  can_ip_forward = false
  project = "<PROJECT_NAME>"
  tags = ["foo", "bar", "allow-lb-service"]

  disk {
    source_image = data.google_compute_image.centos_9.self_link
  }

  network_interface {
    network = google_compute_network.vpc_network.name
  }

  metadata = {
    foo = "bar"
  }

  service_account {
    scopes = ["userinfo-email", "compute-ro", "storage-ro"]
  }
}

resource "google_compute_target_pool" "foobar" {
  name = "my-target-pool"
  project = "<PROJECT_NAME>"
  region = "us-central1"
}

resource "google_compute_instance_group_manager" "foobar" {
  name = "my-igm"
  zone = "us-central1-c"
  project = "<PROJECT_NAME>"
  version {
    instance_template  = google_compute_instance_template.foobar.self_link
    name               = "primary"
  }

  target_pools       = [google_compute_target_pool.foobar.self_link]
  base_instance_name = "terraform"
}

data "google_compute_image" "centos_9" {
  family  = "centos-stream-9"
  project = "centos-cloud"
}

module "lb" {
  source  = "GoogleCloudPlatform/lb/google"
  version = "2.2.0"
  region       = "us-central1"
  name         = "load-balancer"
  service_port = 80
  target_tags  = ["my-target-pool"]
  network      = google_compute_network.vpc_network.name
}