Quickstart: Create an internal load balancer to load balance internal traffic to VMs using Terraform
This quickstart shows you how to deploy a standard internal load balancer and two virtual machines using Terraform. Additional resources include Azure Bastion, NAT Gateway, a virtual network, and the required subnets.
Terraform enables the definition, preview, and deployment of cloud infrastructure. Using Terraform, you create configuration files using HCL syntax. The HCL syntax allows you to specify the cloud provider - such as Azure - and the elements that make up your cloud infrastructure. After you create your configuration files, you create an execution plan that allows you to preview your infrastructure changes before they're deployed. Once you verify the changes, you apply the execution plan to deploy the infrastructure.
- Create an Azure resource group using azurerm_resource_group
- Create an Azure Virtual Network using azurerm_virtual_network
- Create an Azure subnet using azurerm_subnet
- Create an Azure public IP using azurerm_public_ip
- Create an Azure Load Balancer using azurerm_lb
- Create an Azure network interface using azurerm_network_interface
- Create an Azure network interface load balancer backend address pool association using azurerm_network_interface_backend_address_pool_association
- Create an Azure Linux Virtual Machine using azurerm_linux_virtual_machine
- Create an Azure Virtual Machine Extension using azurerm_virtual_machine_extension
- Create an Azure NAT Gateway using azurerm_nat_gateway
- Create an Azure Bastion using azurerm_bastion_host
Prerequisites
Implement the Terraform code
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 = ">=0.12" required_providers { azapi = { source = "azure/azapi" version = "~>1.5" } azurerm = { source = "hashicorp/azurerm" version = "~>2.0" } random = { source = "hashicorp/random" version = "~>3.0" } } } provider "azurerm" { features {} }
Create a file named
main.tf
and insert the following code:resource "random_string" "my_resource_group" { length = 8 upper = false special = false } # Create Resource Group resource "azurerm_resource_group" "my_resource_group" { name = "${var.public_ip_name}-${random_string.my_resource_group.result}" location = var.resource_group_location } # Create Virtual Network resource "azurerm_virtual_network" "my_virtual_network" { name = var.virtual_network_name address_space = ["10.0.0.0/16"] location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name } # Create a subnet in the Virtual Network resource "azurerm_subnet" "my_subnet" { name = var.subnet_name resource_group_name = azurerm_resource_group.my_resource_group.name virtual_network_name = azurerm_virtual_network.my_virtual_network.name address_prefixes = ["10.0.1.0/24"] } # Create a subnet named as "AzureBastionSubnet" in the Virtual Network for creating Azure Bastion resource "azurerm_subnet" "my_bastion_subnet" { name = "AzureBastionSubnet" resource_group_name = azurerm_resource_group.my_resource_group.name virtual_network_name = azurerm_virtual_network.my_virtual_network.name address_prefixes = ["10.0.2.0/24"] } # Create Network Security Group and rules resource "azurerm_network_security_group" "my_nsg" { name = var.network_security_group_name location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name security_rule { name = "ssh" priority = 1022 direction = "Inbound" access = "Allow" protocol = "Tcp" source_port_range = "*" destination_port_range = "22" source_address_prefix = "*" destination_address_prefix = "10.0.1.0/24" } security_rule { name = "web" priority = 1080 direction = "Inbound" access = "Allow" protocol = "Tcp" source_port_range = "*" destination_port_range = "80" source_address_prefix = "*" destination_address_prefix = "10.0.1.0/24" } } # Associate the Network Security Group to the subnet resource "azurerm_subnet_network_security_group_association" "my_nsg_association" { subnet_id = azurerm_subnet.my_subnet.id network_security_group_id = azurerm_network_security_group.my_nsg.id } # Create Public IPs resource "azurerm_public_ip" "my_public_ip" { count = 2 name = "${var.public_ip_name}-${count.index}" location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name allocation_method = "Static" sku = "Standard" } # Create a NAT Gateway for outbound internet access of the Virtual Machines in the Backend Pool of the Load Balancer resource "azurerm_nat_gateway" "my_nat_gateway" { name = var.nat_gateway location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name sku_name = "Standard" } # Associate one of the Public IPs to the NAT Gateway resource "azurerm_nat_gateway_public_ip_association" "my_nat_gateway_ip_association" { nat_gateway_id = azurerm_nat_gateway.my_nat_gateway.id public_ip_address_id = azurerm_public_ip.my_public_ip[0].id } # Associate the NAT Gateway to subnet resource "azurerm_subnet_nat_gateway_association" "my_nat_gateway_subnet_association" { subnet_id = azurerm_subnet.my_subnet.id nat_gateway_id = azurerm_nat_gateway.my_nat_gateway.id } # Create Network Interfaces resource "azurerm_network_interface" "my_nic" { count = 3 name = "${var.network_interface_name}-${count.index}" location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name ip_configuration { name = "ipconfig-${count.index}" subnet_id = azurerm_subnet.my_subnet.id private_ip_address_allocation = "Dynamic" primary = true } } # Create Azure Bastion for accessing the Virtual Machines resource "azurerm_bastion_host" "my_bastion" { name = var.bastion_name location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name sku = "Standard" ip_configuration { name = "ipconfig" subnet_id = azurerm_subnet.my_bastion_subnet.id public_ip_address_id = azurerm_public_ip.my_public_ip[1].id } } # Associate Network Interface to the Backend Pool of the Load Balancer resource "azurerm_network_interface_backend_address_pool_association" "my_nic_lb_pool" { count = 2 network_interface_id = azurerm_network_interface.my_nic[count.index].id ip_configuration_name = "ipconfig-${count.index}" backend_address_pool_id = azurerm_lb_backend_address_pool.my_lb_pool.id } # Create Virtual Machine resource "azurerm_linux_virtual_machine" "my_vm" { count = 3 name = "${var.virtual_machine_name}-${count.index}" location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name network_interface_ids = [azurerm_network_interface.my_nic[count.index].id] size = var.virtual_machine_size os_disk { name = "${var.disk_name}-${count.index}" caching = "ReadWrite" storage_account_type = var.redundancy_type } source_image_reference { publisher = "Canonical" offer = "0001-com-ubuntu-server-jammy" sku = "22_04-lts-gen2" version = "latest" } admin_username = var.username admin_password = var.password disable_password_authentication = false } # Enable virtual machine extension and install Nginx resource "azurerm_virtual_machine_extension" "my_vm_extension" { count = 2 name = "Nginx" virtual_machine_id = azurerm_linux_virtual_machine.my_vm[count.index].id publisher = "Microsoft.Azure.Extensions" type = "CustomScript" type_handler_version = "2.0" settings = <<SETTINGS { "commandToExecute": "sudo apt-get update && sudo apt-get install nginx -y && echo \"Hello World from $(hostname)\" > /var/www/html/index.html && sudo systemctl restart nginx" } SETTINGS } # Create an Internal Load Balancer resource "azurerm_lb" "my_lb" { name = var.load_balancer_name location = azurerm_resource_group.my_resource_group.location resource_group_name = azurerm_resource_group.my_resource_group.name sku = "Standard" frontend_ip_configuration { name = "frontend-ip" subnet_id = azurerm_subnet.my_subnet.id private_ip_address_allocation = "Dynamic" } } resource "azurerm_lb_backend_address_pool" "my_lb_pool" { loadbalancer_id = azurerm_lb.my_lb.id name = "test-pool" } resource "azurerm_lb_probe" "my_lb_probe" { resource_group_name = azurerm_resource_group.my_resource_group.name loadbalancer_id = azurerm_lb.my_lb.id name = "test-probe" port = 80 } resource "azurerm_lb_rule" "my_lb_rule" { resource_group_name = azurerm_resource_group.my_resource_group.name loadbalancer_id = azurerm_lb.my_lb.id name = "test-rule" protocol = "Tcp" frontend_port = 80 backend_port = 80 disable_outbound_snat = true frontend_ip_configuration_name = "frontend-ip" probe_id = azurerm_lb_probe.my_lb_probe.id backend_address_pool_ids = [azurerm_lb_backend_address_pool.my_lb_pool.id] }
Create a file named
variables.tf
and insert the following code:variable "resource_group_location" { type = string default = "eastus" description = "Location of the resource group." } variable "resource_group_name" { type = string default = "test-group" description = "Name of the resource group." } variable "username" { type = string default = "microsoft" description = "The username for the local account that will be created on the new VM." } variable "password" { type = string default = "Microsoft@123" description = "The passoword for the local account that will be created on the new VM." } variable "virtual_network_name" { type = string default = "test-vnet" description = "Name of the Virtual Network." } variable "subnet_name" { type = string default = "test-subnet" description = "Name of the subnet." } variable public_ip_name { type = string default = "test-public-ip" description = "Name of the Public IP for the NAT Gateway." } variable "nat_gateway" { type = string default = "test-nat" description = "Name of the NAT gateway." } variable "bastion_name" { type = string default = "test-bastion" description = "Name of the Bastion." } variable network_security_group_name { type = string default = "test-nsg" description = "Name of the Network Security Group." } variable "network_interface_name" { type = string default = "test-nic" description = "Name of the Network Interface." } variable "virtual_machine_name" { type = string default = "test-vm" description = "Name of the Virtual Machine." } variable "virtual_machine_size" { type = string default = "Standard_B2s" description = "Size or SKU of the Virtual Machine." } variable "disk_name" { type = string default = "test-disk" description = "Name of the OS disk of the Virtual Machine." } variable "redundancy_type" { type = string default = "Standard_LRS" description = "Storage redundancy type of the OS disk." } variable "load_balancer_name" { type = string default = "test-lb" description = "Name of the Load Balancer." }
Create a file named
outputs.tf
and insert the following code:output "private_ip_address" { value = "http://${azurerm_lb.my_lb.private_ip_address}" }
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 ranterraform plan -out main.tfplan
. - If you specified a different filename for the
-out
parameter, use that same filename in the call toterraform apply
. - If you didn't use the
-out
parameter, callterraform apply
without any parameters.
Verify the results
When you apply the execution plan, Terraform displays the frontend private IP address. If you've cleared the screen, you can retrieve that value with the following Terraform command:
echo $(terraform output -raw private_ip_address)
Login to the VM which is not associated to the backend pool of load balancer using Bastion.
Run the curl command to access the custom web page of the Nginx web server using the frontend private IP address of the load balancer.
curl http://<Frontend IP address>
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.
- The
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
In this quickstart, you:
Created an internal Azure Load Balancer
Attached 2 VMs to the load balancer
Configured the load balancer traffic rule, health probe, and then tested the load balancer
To learn more about Azure Load Balancer, continue to:
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