Check if Azure VM name exists before deploying arm template - azure

Question

I am trying to use Azure powershell to get VM name (Eg: demovm01, where the VM name is demovm and the suffix is 01.
I want to get the output and automatically append a new suffix of 02 if 01 already exists.
Sample script to get vm name:
$getvm = Get-AzVM -Name "$vmname" -ResourceGroupName "eodemofunction" -ErrorVariable notPresent -ErrorAction SilentlyContinue
if ($notPresent) {
Write-Output "VM not found. Creating now"
}
else {
Write-Output "VM exists."
return $true
}
I want to be able to inject this new vm name to an arm deploy to deploy

Answer 1

This should do it. Will increment until no VM is found and use a simple -replace to inject to your json file. Will also return all thr VM values that are already present in Azure
$i=1
$vmname_base = "vmserver"
$VMexists = #()
do {
#invert int value to double digit string
$int = $i.tostring('00')
$getvm = Get-AzVM -Name "$vmname_base$int" -ResourceGroupName "eodemofunction" -ErrorVariable notPresent -ErrorAction SilentlyContinue
if ($notPresent) {
Write-Output "VM not found. Creating now"
Write-Output "VM created name is $vmname_base$int"
#Set condition to end do while loop
VMcreated = "true"
#commands to inject to json here. I always find replace method the easiest
$JSON = Get-Content azuredeploy.parameters.json
$JSON = $JSON -replace ("Servername","$vmname_base$int")
$JSON | Out-File azuredeploy.parameters.json -Force
}
else {
Write-Output "VMexists."
# Add existing VM to array
$VMexists += "$vmname_base$int"
# Increment version, ie. 01 to 02 to 03 etc
$i++
}
} while ($VMcreated -ne "true")
return $VMexists

Answer 2

Your command could be like below, the $newvmname is that you want.
$vmname = "demovm01"
$getvm = Get-AzVM -Name "$vmname" -ResourceGroupName "<group name>" -ErrorVariable notPresent -ErrorAction SilentlyContinue
if ($notPresent) {
Write-Output "VM not found. Creating now"
}
else {
Write-Output "VM exists."
if($getvm.Name -like '*01'){
$newvmname = $vmname.TrimEnd('01')+"02"
}
Write-Output $newvmname
return $true
}