Azure PowerShell Function to renew a Azure AD Change Notification Subscription. Associated Blogpost https://blog.darrenjrobinson.com/subscribing-to-azure-ad-change-notifications-with-powershell/

run.ps1

# Input bindings are passed in via param block.
param($Timer)

# Get the current universal time in the default string format
$currentUTCtime = (Get-Date).ToUniversalTime()

# The 'IsPastDue' porperty is 'true' when the current function invocation is later than scheduled.
if ($Timer.IsPastDue) {
    Write-Host "PowerShell timer is running late!"
}

write-host "AUTHSTRING: grant_type=password&resource=https://graph.microsoft.com&client_id=$($env:graphAutomationClientID)&username=$($env:graphAutomationUserUPN)&password=$($env:graphAutomationUserPWD)&client_secret=$($env:graphAutomationSecret)"

# Get a new Access Token
$delegatedToken = (Invoke-RestMethod -uri "https://login.microsoftonline.com/$($env:graphAutomationTenantID)/oauth2/token" `
        -Method Post `
        -Headers @{"Content-Type" = "application/x-www-form-urlencoded"} `
        -Body "grant_type=password&resource=https://graph.microsoft.com&client_id=$($env:graphAutomationClientID)&username=$($env:graphAutomationUserUPN)&password=$($env:graphAutomationUserPWD)&client_secret=$($env:graphAutomationSecret)").access_token

write-host "DELEGATEDTOKEN: `r`n  $($delegatedToken)"

# Get AAD Change Notification Subscription 
$usersNotificationSubscription = Invoke-RestMethod -method GET `
    -uri "https://graph.microsoft.com/v1.0/subscriptions/$($env:notificationSubscriptionID)" `
    -Headers @{Authorization = "Bearer $($delegatedToken)"; "content-type" = "application/json" } 

write-host "SUBSCRIPTIONExpiry: $($usersNotificationSubscription.expirationDateTime)"
write-host "SUBSCRIPTIONClientState: $($usersNotificationSubscription.clientState)"

# Update Subscription 
$expiryMaxLength = 3
$expiryHours = ($expiryMaxLength * 24) / 2
$notificationExpiry = (get-date).addHours($expiryHours).ToUniversalTime() 
$utcExpiry = get-date $notificationExpiry -Format yyyy-MM-ddThh:mm:ss.0000000Z

$updateSubscriptionBody = @{
    expirationDateTime = $utcExpiry
}

$extendUserNotificationSubscription = Invoke-RestMethod -method PATCH `
    -Uri "https://graph.microsoft.com/v1.0/subscriptions/$($env:notificationSubscriptionID)" `
    -body ($updateSubscriptionBody | convertTo-json) `
    -Headers @{Authorization = "Bearer $($delegatedToken)"; "content-type" = "application/json"}

write-host "NEW_SUBSCRIPTIONExpiry: $($extendUserNotificationSubscription.expirationDateTime)"
write-host "VALIDATE_SUBSCRIPTIONClientState: $($extendUserNotificationSubscription.clientState)"

# Write an information log with the current time.
Write-Host "PowerShell timer trigger function ran! TIME: $currentUTCtime"