Quickstart: Create a Linux VM cluster in Azure using Terraform

Article
08/22/2024

Applies to: ✔️ Linux VMs

This article shows you how to create a Linux VM cluster (containing two Linux VM instances) in Azure using Terraform.

In this article, you learn how to:

Create a random value for the Azure resource group name using random_pet.
Create an Azure resource group using azurerm_resource_group.
Create a virtual network using azurerm_virtual_network
Create a subnet using azurerm_subnet
Create a public IP using azurerm_public_ip
Create a load balancer using azurerm_lb
Create a load balancer address pool using azurerm_lb_backend_address_pool
Create a network interface using azurerm_network_interface
Create a managed disk using azurerm_managed_disk
Create a availability set using azurerm_availability_set
Create a Linux virtual machine using azurerm_linux_virtual_machine
Create an AzAPI resource azapi_resource.
Create an AzAPI resource to generate an SSH key pair using azapi_resource_action.

Prerequisites

Install and configure Terraform

Implement the Terraform code

Note

The sample code for this article is located in the Azure Terraform GitHub repo. You can view the log file containing the test results from current and previous versions of Terraform.

See more articles and sample code showing how to use Terraform to manage Azure resources

Create a directory in which to test the sample Terraform code and make it the current directory.

Create a file named providers.tf and insert the following code:

terraform {
  required_version = ">=1.0"
  required_providers {
    azapi = {
      source  = "azure/azapi"
      version = "~>1.5"
    }
    azurerm = {
      source  = "hashicorp/azurerm"
      version = "~>3.0"
    }
    random = {
      source  = "hashicorp/random"
      version = "~>3.0"
    }
  }
}
provider "azurerm" {
  features {}
}

Create a file named ssh.tf and insert the following code:

resource "random_pet" "ssh_key_name" {
  prefix    = "ssh"
  separator = ""
}

resource "azapi_resource_action" "ssh_public_key_gen" {
  type        = "Microsoft.Compute/sshPublicKeys@2022-11-01"
  resource_id = azapi_resource.ssh_public_key.id
  action      = "generateKeyPair"
  method      = "POST"

  response_export_values = ["publicKey", "privateKey"]
}

resource "azapi_resource" "ssh_public_key" {
  type      = "Microsoft.Compute/sshPublicKeys@2022-11-01"
  name      = random_pet.ssh_key_name.id
  location  = azurerm_resource_group.rg.location
  parent_id = azurerm_resource_group.rg.id
}

output "key_data" {
  value = azapi_resource_action.ssh_public_key_gen.output.publicKey
}

Create a file named main.tf and insert the following code:

resource "random_pet" "rg_name" {
  prefix = var.resource_group_name_prefix
}

resource "azurerm_resource_group" "rg" {
  name     = random_pet.rg_name.id
  location = var.resource_group_location
}

resource "random_pet" "azurerm_virtual_network_name" {
  prefix = "vnet"
}

resource "azurerm_virtual_network" "test" {
  name                = random_pet.azurerm_virtual_network_name.id
  address_space       = ["10.0.0.0/16"]
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
}

resource "random_pet" "azurerm_subnet_name" {
  prefix = "sub"
}

resource "azurerm_subnet" "test" {
  name                 = random_pet.azurerm_subnet_name.id
  resource_group_name  = azurerm_resource_group.rg.name
  virtual_network_name = azurerm_virtual_network.test.name
  address_prefixes     = ["10.0.2.0/24"]
}

resource "azurerm_public_ip" "test" {
  name                = "publicIPForLB"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  allocation_method   = "Static"
}

resource "azurerm_lb" "test" {
  name                = "loadBalancer"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name

  frontend_ip_configuration {
    name                 = "publicIPAddress"
    public_ip_address_id = azurerm_public_ip.test.id
  }
}

resource "azurerm_lb_backend_address_pool" "test" {
  loadbalancer_id = azurerm_lb.test.id
  name            = "BackEndAddressPool"
}

resource "azurerm_network_interface" "test" {
  count               = 2
  name                = "acctni${count.index}"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name

  ip_configuration {
    name                          = "testConfiguration"
    subnet_id                     = azurerm_subnet.test.id
    private_ip_address_allocation = "Dynamic"
  }
}

resource "azurerm_availability_set" "avset" {
  name                         = "avset"
  location                     = azurerm_resource_group.rg.location
  resource_group_name          = azurerm_resource_group.rg.name
  platform_fault_domain_count  = 2
  platform_update_domain_count = 2
  managed                      = true
}

resource "random_pet" "azurerm_linux_virtual_machine_name" {
  prefix = "vm"
}

resource "azurerm_linux_virtual_machine" "test" {
  count                 = 2
  name                  = "${random_pet.azurerm_linux_virtual_machine_name.id}${count.index}"
  location              = azurerm_resource_group.rg.location
  availability_set_id   = azurerm_availability_set.avset.id
  resource_group_name   = azurerm_resource_group.rg.name
  network_interface_ids = [azurerm_network_interface.test[count.index].id]
  size                  = "Standard_DS1_v2"

  # Uncomment this line to delete the OS disk automatically when deleting the VM
  # delete_os_disk_on_termination = true

  # Uncomment this line to delete the data disks automatically when deleting the VM
  # delete_data_disks_on_termination = true

  source_image_reference {
    publisher = "Canonical"
    offer     = "UbuntuServer"
    sku       = "16.04-LTS"
    version   = "latest"
  }

  admin_ssh_key {
    username   = var.username
    public_key = azapi_resource_action.ssh_public_key_gen.output.publicKey
  }

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
    name                 = "myosdisk${count.index}"
  }

  computer_name  = "hostname"
  admin_username = var.username
}

resource "azurerm_managed_disk" "test" {
  count                = 2
  name                 = "datadisk_existing_${count.index}"
  location             = azurerm_resource_group.rg.location
  resource_group_name  = azurerm_resource_group.rg.name
  storage_account_type = "Standard_LRS"
  create_option        = "Empty"
  disk_size_gb         = "1024"
}

resource "azurerm_virtual_machine_data_disk_attachment" "test" {
  count              = 2
  managed_disk_id    = azurerm_managed_disk.test[count.index].id
  virtual_machine_id = azurerm_linux_virtual_machine.test[count.index].id
  lun                = "10"
  caching            = "ReadWrite"
}

Create a file named variables.tf and insert the following code:

variable "resource_group_location" {
  type        = string
  description = "Location for all resources."
  default     = "eastus"
}

variable "resource_group_name_prefix" {
  type        = string
  description = "Prefix of the resource group name that's combined with a random ID so name is unique in your Azure subscription."
  default     = "rg"
}

variable "username" {
  type        = string
  description = "The username for the local account that will be created on the new VM."
  default     = "azureadmin"
}

Create a file named outputs.tf and insert the following code:

output "resource_group_name" {
  value = azurerm_resource_group.rg.name
}

output "virtual_network_name" {
  value = azurerm_virtual_network.test.name
}

output "subnet_name" {
  value = azurerm_subnet.test.name
}

output "linux_virtual_machine_names" {
  value = [for s in azurerm_linux_virtual_machine.test : s.name[*]]
}

Initialize Terraform

Run terraform init to initialize the Terraform deployment. This command downloads the Azure provider required to manage your Azure resources.

terraform init -upgrade

Key points:

The -upgrade parameter upgrades the necessary provider plugins to the newest version that complies with the configuration's version constraints.

Create a Terraform execution plan

Run terraform plan to create an execution plan.

terraform plan -out main.tfplan

Key points:

The terraform plan command creates an execution plan, but doesn't execute it. Instead, it determines what actions are necessary to create the configuration specified in your configuration files. This pattern allows you to verify whether the execution plan matches your expectations before making any changes to actual resources.
The optional -out parameter allows you to specify an output file for the plan. Using the -out parameter ensures that the plan you reviewed is exactly what is applied.

Apply a Terraform execution plan

Run terraform apply to apply the execution plan to your cloud infrastructure.

terraform apply main.tfplan

Key points:

The example terraform apply command assumes you previously ran terraform plan -out main.tfplan.
If you specified a different filename for the -out parameter, use that same filename in the call to terraform apply.
If you didn't use the -out parameter, call terraform apply without any parameters.

Cost information isn't presented during the virtual machine creation process for Terraform like it is for the Azure portal. If you want to learn more about how cost works for virtual machines, see the Cost optimization Overview page.

Get the Azure resource group name.

resource_group_name=$(terraform output -raw resource_group_name)

Run az vm list with a JMESPath query to display the names of the virtual machines created in the resource group.
```
az vm list \
  --resource-group $resource_group_name \
  --query "[].{\"VM Name\":name}" -o table
```

Get the Azure resource group name.

$resource_group_name=$(terraform output -raw resource_group_name)

Run Get-AzVm to display the names of all the virtual machines in the resource group.
```
Get-AzVm -ResourceGroupName $resource_group_name
```

Clean up resources

When you no longer need the resources created via Terraform, do the following steps:

Run terraform plan and specify the destroy flag.
```
terraform plan -destroy -out main.destroy.tfplan
```
Key points:
- The terraform plan command creates an execution plan, but doesn't execute it. Instead, it determines what actions are necessary to create the configuration specified in your configuration files. This pattern allows you to verify whether the execution plan matches your expectations before making any changes to actual resources.
- The optional -out parameter allows you to specify an output file for the plan. Using the -out parameter ensures that the plan you reviewed is exactly what is applied.
Run terraform apply to apply the execution plan.
```
terraform apply main.destroy.tfplan
```

Troubleshoot Terraform on Azure

Troubleshoot common problems when using Terraform on Azure

Next steps

Azure Linux virtual machine tutorials

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Quickstart: Create a Linux VM cluster in Azure using Terraform

Prerequisites

Implement the Terraform code

Initialize Terraform

Create a Terraform execution plan

Apply a Terraform execution plan

Verify the results

Clean up resources

Troubleshoot Terraform on Azure

Next steps

Feedback

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