I have an Azure VM which is running a C# Windows Service which is happily logging telemetry to App Insights. However, when it went live, there was then a business requirement for resilience so I created a VMSS from the VM Image running 2 instances, however when running as a scale set, the service no longer log any telemetry, even though the service is running correctly. If I restore the image as a single VM, it immediately starts logging again.
My assumption is that there is something in the load balancer which is blocking the telemetry. Do I need to set an outbound rule?
Any pointers would be greatly appriciated!
Cheers
James
It is probably not because it is in the scale set, but rather that the scale set is deployed behind a firewall that is causing the traffic to App Insights to be blocked.
You could fix it by allowing out bound traffic on port 443.
But a better solution is to create a private link between the VNET containing your VM's and App Insights. See: https://learn.microsoft.com/en-us/azure/azure-monitor/logs/private-link-configure