Using PowerShell to add an Availability Set to Backend Pool for Azure Load Balancer

Question

Despite having used the official documentation, I'm struggling to find the right PowerShell to associate an availability set (of 2 VMs) with their first IP, to the backend pool configuration for an Azure load balancer.

Can anyone help?

Answer 1

You could use Get-AzureRmAvailabilitySet to get and then enumerate the VMs in the availability set. Then use Set-AzureRmNetworkInterface to set the LoadBalancerBackendAddressPool on each of the VMs NICs?

This link has some good code around this https://docs.microsoft.com/en-us/azure/networking/scripts/load-balancer-windows-powershell-sample-nlb

Answer 2

I've ran into the same issue where I my goal was to update the Load Balancer backendPool based on the machines in an Availability Set.

I created a script:

<#
.SYNOPSIS
    Updates the Azure Load Balancer backend Pool
.DESCRIPTION
    Add's vm's to the backend pool of the specified Azure Load Balancer.
.OUTPUTS
    Progress messages
#>
[CmdletBinding()]
Param(
    [Parameter(Mandatory = $True)]
    [string]$loadBalancerName,
    [Parameter(Mandatory = $True)]
    [string]$resourceGroupName,
    [Parameter(Mandatory = $True)]
    [string]$debugDeploymentDebugLevel,
    [Parameter(Mandatory = $True)]
    [string]$availabilitySetName,
    [Parameter(Mandatory = $True)]
    [string]$backendPoolName
)

$ErrorActionPreference = "Stop"

Try {
    $loadBalancer = Get-AzureRmLoadBalancer `
        -Name $loadBalancerName `
        -ResourceGroupName $resourceGroupName `
        -ErrorAction Stop
}
Catch {
    Write-Warning "No Load Balancer found with name $loadBalancerName in resource group $resourceGroupName"
    Return
}

try {
    $backendPool = Get-AzureRmLoadBalancerBackendAddressPoolConfig `
        -Name $backendPoolName `
        -LoadBalancer $loadBalancer
}
catch {
    #Write-Warning "no Backend Pool found with the name $backendPoolName in the load balancer with the name $loadBalancerName"
    Return
}

try {
    $AvSet = Get-AzureRmAvailabilitySet `
        -Name $availabilitySetName `
        -ResourceGroupName (Get-AzureRmResource | Where-Object {
            ($_.Name -eq $availabilitySetName) -and `
            ($_.ResourceType -eq "Microsoft.Compute/AvailabilitySets")}).ResourceGroupName
}
catch {
    Write-Warning "no AvailabilitySet found with the name $availabilitySetName in resource group $availabilitySetResourceGroup"
    Return
}

ForEach ($id in $avSet.VirtualMachinesReferences.id) {

    $nic = Get-AzureRmNetworkInterface | Where-Object {($_.VirtualMachine.id).ToLower() -eq ($id).ToLower()}
    $nic.IpConfigurations[0].LoadBalancerBackendAddressPools = $backendPool

    Set-AzureRmNetworkInterface -NetworkInterface $nic -AsJob    
}    

If ($ErrorMessages) {
    Write-Error "Deployment returned the following errors: $ErrorMessages";
    Return
}

You can find on my github as well: https://github.com/azurekid/blog/blob/master/Update-BackendPool.ps1

Hope this helps ;-)