Hi,
I have a VM Scale Set running between 2 and 4 machines behind a Load Balancer and serving some production web traffic. This is a system I've brought over from AWS.
In AWS the machines were based on Ubuntu 14.04.0 LTS from mid-2014 so I choose a matching Azure Ubuntu image to minimise migration issues.
I have since verified the system operates on the newer Ubuntu 14.04.4 from February 2016 and I am attempting to update my VM Scale Set so that new machines provisioned during a scale-out event will use the new base image.
In my ARM template I have changed the Scale Set's virtualMachineProfile.storageProfile.imageReference from this:
"imageReference": {
"publisher": "Canonical",
"offer": "UbuntuServer",
"sku": "14.04.0-LTS",
"version": "14.04.201406061"
}
To this:
"imageReference": {
"publisher": "Canonical",
"offer": "UbuntuServer",
"sku": "14.04.4-LTS",
"version": "14.04.201602220"
}
But when I attempt to deploy the template I get the error message:
Changing property 'imageReference.sku' is not allowed.
It seems I am now back in the same situation of incurring an outage as per my previous question here:
https://social.msdn.microsoft.com/Forums/en-US/2e81dd6a-1741-48aa-ab02-fc5c8c4450c1/how-to-update-vm-scale-sets-customdata-without-down-time
In AWS, replacing the Launch Configuration of a AutoScaling Group so that new machines will be provisioned from a new image (AMI) is a standard operation.
Ideas on how to solve this are appreciated.
Regards,
Jason