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

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Terraform Provider - Linode

Overview

Learning how to configure complex environments with Terraform is a must-have skill. In this hands-on lab, we will provision an autoscaling group with a load balancer.

Objectives: Successfully complete this lab by achieving the following learning objectives:

Create a Service Account

  1. From Google Cloud console’s main navigation, choose IAM & Admin > Service Accounts.
  2. Click Create service account.
  3. Give your service account a name.
  4. Click Create.
  5. In the roles dropdown, select Project > Owner.
  6. Click Continue and then Done.

Log in to the Host Instance and Ensure Terraform Is Installed

  1. From Google Cloud navigation, choose Compute Engine > VM instances.
  1. Click SSH next to terraform-instance.
  2. Use root privileges:
sudo -i
  1. Change into the root directory:
cd /
  1. Input the path to communicate with Terraform into the /etc/profile file:
echo "PATH='$PATH:/downloads/'">> /etc/profile
  1. Run the following in order to be able to call Terraform:
source /etc/profile
  1. Call Terraform:
terraform

Create a Service Account Key within the Instance

  1. Allow the SDK to communicate with GCP:gcloud auth login
  2. Enter Y at the prompt.
  3. Click on the link in the output.
  4. Select the Cloud Student account.
  5. Click Allow.
  6. Copy the code provided.
  7. Paste the code into the terminal.
  1. Create the service account key:
gcloud iam service-accounts keys create /downloads/auto-scaling.json --iam-account <SERVICE_ACCOUNT_EMAIL>

In our case:

gcloud iam service-accounts keys create /downloads/auto-scaling.json --iam-account auto-scaling@using-terraf-159-400aac65.iam.gserviceaccount.com

Create and Deploy the Configuration File

  1. Create a main.tf file:
vim main.tf
  1. 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_7.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_7" {
  family  = "centos-7"
  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
}
  1. Run below command to replace the project Name:
sed -i 's/<PROJECT_NAME>/using-terraf-159-400aac65/g' main.tf
  1. Initialize the configuration file:
terraform init
  1. Validate the configuration file:
terraform validate
  1. Create the execution plan:
terraform plan
  1. Apply the changes:
terraform apply
  1. Enter yes at the prompt. It will take a few minutes to complete.
  2. In the Google Cloud console, refresh the VM instances page. We should now see our two new instances listed.
  1. Navigate to VPC network > VPC networks. We should see our new-terraform-network listed.
  1. Navigate to Network services > Load balancing. We should see our two new load balancers listed.

Happy Learning !!!


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