Looking to run a Powershell update for Azure from a list.

Hello Mike_F_MF,

I think you have a problem in your Foreach-Object statement.
If you want to use ForEach-Object you need to pipe (|) some collection to it.
In your case you can run something like this:

$username | ForEach-Object{

# Get the user to assign, and the service principal for the app to assign to
$user = Get-AzureADUser -ObjectId $_
$sp = Get-AzureADServicePrincipal -Filter "displayName eq '$app_name'"
$appRole = $sp.AppRoles | Where-Object { $_.DisplayName -eq $app_role_name }

# Assign the user to the app role
New-AzureADUserAppRoleAssignment -ObjectId $user.ObjectId -PrincipalId $user.ObjectId -ResourceId $sp.ObjectId -Id $appRole.Id
}

Another option would be to use foreach($item in $Collection){...} :

foreach($u in $username){
# Get the user to assign, and the service principal for the app to assign to
$user = Get-AzureADUser -ObjectId $u
$sp = Get-AzureADServicePrincipal -Filter "displayName eq '$app_name'"
$appRole = $sp.AppRoles | Where-Object { $_.DisplayName -eq $app_role_name }

# Assign the user to the app role
New-AzureADUserAppRoleAssignment -ObjectId $user.ObjectId -PrincipalId $user.ObjectId -ResourceId $sp.ObjectId -Id $appRole.Id
}

Hope that helps.