A script to create a new CName on an existing zone in Azure. You can use this script in an Azure DevOps pipeline using a service account with the proper permissions.

New-CName.ps1

param(
    [CmdletBinding()]

    # Subscription ID
    [Parameter(Position=0, Mandatory=$true)]
    [string]$subId,
    
    # DNS Resource Group Name
    [Parameter(Position=1, Mandatory=$true)]
    [string]$resourceGroup,

    # DNS Zone Name
    [Parameter(Position=2, Mandatory=$true)]
    [string]$zoneName,

    # CName Record Name
    [Parameter(Position=3, Mandatory=$true)]
    [string]$cnameName,

    # Value CName Record Points To
    [Parameter(Position=4, Mandatory=$true)]
    [string]$cnameValue
)

#If the Azure AZ module is not loaded, load it.
if(-not (Get-Module Az)) {
    Install-Module -Name Az -AllowClobber -Scope CurrentUser -SkipPublisherCheck
}

#Set Azure Context
Set-AzContext -SubscriptionId $subId

#Get the record set to see if it already exists and if not, create it
New-AzDnsRecordSet -Name $cnameName -RecordType CNAME -ZoneName $zoneName -ResourceGroupName $resourceGroup -Ttl 3600 -DnsRecords (New-AzDnsRecordConfig -Cname $cnameValue) -Overwrite -Confirm:$False