Azure Route Table Modification With Powershell - azure

Question

We have over 20 route tables that we need to be able to quickly modify.
We have 2 NVAs that could act as the next hop but we are not able to find the correct solution.
We are stuck at this:
$groupname = Get-AzResourceGroup | Out-GridView –PassThru | Select -ExpandProperty ResourceGroupName
$rt = Get-AzRouteTable -ResourceGroupName $groupname | Out-GridView -PassThru
$oldroutes = Get-AzRouteTable -ResourceGroupName $groupname | Get-AzRouteConfig | Where-Object -Property NextHopIpAddress -Like 1.1.1.1 | Select -ExpandProperty Name
foreach ($oldroutes in $oldroutes)
{
Set-AzRouteConfig -RouteTable $rt -Name $oldroute -NextHopIpAddress 2.2.2.2 | Set-AzRoutetable }
This works to the part that is able to go through all Route Tables and identify all routes that have next hop as 1.1.1.1 and store them in a variable called $oldroutes and only selecting the route Name which is needed by the Set-AZRouteConfig command.
It runs correct up until the Set part. Instead of Modifying it just sets the NextHopIpAddress as 2.2.2.2 and deletes all other values, so when we try to commit the changes we get an error.
Set-AzRoutetable : Address prefix string for resource ...... cannot be null
Has anyone done this or are we missing anything maybe?
Thank you in advance!

Answer 1

I can reproduce your issue, when using Set-AzRouteConfig | Set-AzRoutetable , the parameter -AddressPrefix is needed, if you don't want change it, you could specify it with the original one. And if you want to set -NextHopIpAddress, you need to specify the -NextHopType only with VirtualAppliance. And this part $oldroutes in $oldroutes is also has a mistake, it should be $oldroute in $oldroutes.
So in summary, your script should be like below.
$groupname = Get-AzResourceGroup | Out-GridView –PassThru | Select -ExpandProperty ResourceGroupName
$rt = Get-AzRouteTable -ResourceGroupName $groupname | Out-GridView -PassThru
$oldroutes = Get-AzRouteTable -ResourceGroupName $groupname | Get-AzRouteConfig | Where-Object -Property NextHopIpAddress -Like 1.1.1.1
foreach ($oldroute in $oldroutes)
{
Set-AzRouteConfig -RouteTable $rt -Name $oldroute.Name -AddressPrefix $oldroute.AddressPrefix -NextHopType VirtualAppliance -NextHopIpAddress 2.2.2.2 | Set-AzRoutetable
}