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Quickstart: Create an internal load balancer to load balance VMs using Bicep

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This quickstart describes how to use Bicep to create an internal Azure load balancer.

Diagram of resources deployed for internal load balancer.

Bicep is a domain-specific language (DSL) that uses declarative syntax to deploy Azure resources. It provides concise syntax, reliable type safety, and support for code reuse. Bicep offers the best authoring experience for your infrastructure-as-code solutions in Azure.

Prerequisites

If you don't have an Azure subscription, create a free account before you begin.

Review the Bicep file

The Bicep file used in this quickstart is from the Azure Quickstart Templates.

@description('Admin username')
param adminUsername string

@description('Admin password')
@secure()
param adminPassword string

@description('Prefix to use for VM names')
param vmNamePrefix string = 'BackendVM'

@description('Location for all resources.')
param location string = resourceGroup().location

@description('Size of the virtual machines')
param vmSize string = 'Standard_D2s_v3'

var availabilitySetName = 'AvSet'
var storageAccountType = 'Standard_LRS'
var storageAccountName = uniqueString(resourceGroup().id)
var virtualNetworkName = 'vNet'
var subnetName = 'backendSubnet'
var loadBalancerName = 'ilb'
var networkInterfaceName = 'nic'
var subnetRef = resourceId('Microsoft.Network/virtualNetworks/subnets', virtualNetworkName, subnetName)
var numberOfInstances = 2

resource storageAccount 'Microsoft.Storage/storageAccounts@2023-01-01' = {
  name: storageAccountName
  location: location
  sku: {
    name: storageAccountType
  }
  kind: 'StorageV2'
}

resource availabilitySet 'Microsoft.Compute/availabilitySets@2023-09-01' = {
  name: availabilitySetName
  location: location
  sku: {
    name: 'Aligned'
  }
  properties: {
    platformUpdateDomainCount: 2
    platformFaultDomainCount: 2
  }
}

resource virtualNetwork 'Microsoft.Network/virtualNetworks@2023-09-01' = {
  name: virtualNetworkName
  location: location
  properties: {
    addressSpace: {
      addressPrefixes: [
        '10.0.0.0/16'
      ]
    }
    subnets: [
      {
        name: subnetName
        properties: {
          addressPrefix: '10.0.2.0/24'
        }
      }
    ]
  }
}

resource networkInterface 'Microsoft.Network/networkInterfaces@2023-09-01' = [for i in range(0, numberOfInstances): {
  name: '${networkInterfaceName}${i}'
  location: location
  properties: {
    ipConfigurations: [
      {
        name: 'ipconfig1'
        properties: {
          privateIPAllocationMethod: 'Dynamic'
          subnet: {
            id: subnetRef
          }
          loadBalancerBackendAddressPools: [
            {
              id: resourceId('Microsoft.Network/loadBalancers/backendAddressPools', loadBalancerName, 'BackendPool1')
            }
          ]
        }
      }
    ]
  }
  dependsOn: [
    virtualNetwork
    loadBalancer
  ]
}]

resource loadBalancer 'Microsoft.Network/loadBalancers@2023-09-01' = {
  name: loadBalancerName
  location: location
  sku: {
    name: 'Standard'
  }
  properties: {
    frontendIPConfigurations: [
      {
        properties: {
          subnet: {
            id: subnetRef
          }
          privateIPAddress: '10.0.2.6'
          privateIPAllocationMethod: 'Static'
        }
        name: 'LoadBalancerFrontend'
      }
    ]
    backendAddressPools: [
      {
        name: 'BackendPool1'
      }
    ]
    loadBalancingRules: [
      {
        properties: {
          frontendIPConfiguration: {
            id: resourceId('Microsoft.Network/loadBalancers/frontendIpConfigurations', loadBalancerName, 'LoadBalancerFrontend')
          }
          backendAddressPool: {
            id: resourceId('Microsoft.Network/loadBalancers/backendAddressPools', loadBalancerName, 'BackendPool1')
          }
          probe: {
            id: resourceId('Microsoft.Network/loadBalancers/probes', loadBalancerName, 'lbprobe')
          }
          protocol: 'Tcp'
          frontendPort: 80
          backendPort: 80
          idleTimeoutInMinutes: 15
        }
        name: 'lbrule'
      }
    ]
    probes: [
      {
        properties: {
          protocol: 'Tcp'
          port: 80
          intervalInSeconds: 15
          numberOfProbes: 2
        }
        name: 'lbprobe'
      }
    ]
  }
  dependsOn: [
    virtualNetwork
  ]
}

resource vm 'Microsoft.Compute/virtualMachines@2023-09-01' = [for i in range(0, numberOfInstances): {
  name: '${vmNamePrefix}${i}'
  location: location
  properties: {
    availabilitySet: {
      id: availabilitySet.id
    }
    hardwareProfile: {
      vmSize: vmSize
    }
    osProfile: {
      computerName: '${vmNamePrefix}${i}'
      adminUsername: adminUsername
      adminPassword: adminPassword
    }
    storageProfile: {
      imageReference: {
        publisher: 'MicrosoftWindowsServer'
        offer: 'WindowsServer'
        sku: '2019-Datacenter'
        version: 'latest'
      }
      osDisk: {
        createOption: 'FromImage'
      }
    }
    networkProfile: {
      networkInterfaces: [
        {
          id: networkInterface[i].id
        }
      ]
    }
    diagnosticsProfile: {
      bootDiagnostics: {
        enabled: true
        storageUri: storageAccount.properties.primaryEndpoints.blob
      }
    }
  }
}]

output location string = location
output name string = loadBalancer.name
output resourceGroupName string = resourceGroup().name
output resourceId string = loadBalancer.id

Multiple Azure resources have been defined in the Bicep file:

Deploy the Bicep file

  1. Save the Bicep file as main.bicep to your local computer.

  2. Deploy the Bicep file using either Azure CLI or Azure PowerShell.

    az group create --name CreateIntLBQS-rg --location eastus
az deployment group create --resource-group CreateIntLBQS-rg --template-file main.bicep --parameters adminUsername=AzureAdmin

    Note

    Replace <admin-user> with the admin username. You'll also be prompted to enter adminPassword.

    When the deployment finishes, you should see a message indicating the deployment succeeded.

Review deployed resources

Use the Azure portal, Azure CLI, or Azure PowerShell to list the deployed resources in the resource group.

az resource list --resource-group CreateIntLBQS-rg

Clean up resources

When no longer needed, use the Azure portal, Azure CLI, or Azure PowerShell to delete the resource group and its resources.

az group delete --name CreateIntLBQS-rg

Next steps

For a step-by-step tutorial that guides you through the process of creating a Bicep file, see:

Quickstart: Create Bicep files with Visual Studio Code