Reporting on an Azure IaaS VM cost – have I included everything?

We had arranged our Azure subscriptions to have each resource group representing an application so that all resources that belonged to an application are deployed within a resource group. This enabled us make it easier to grant management access rights to resources on per application basis. We were able to do costing reporting easier for each application as we just needed to report at the resource group level which would then include all the resources for the application. Then when we wanted to decommission the application we could just delete the resource group which would delete all the resources related to the application.

Over time, application owners wanted to drill down further with costing and to know the actual cost on a per server basis within the application. By using Azure cost management, you can filter down to the resource level which you can see that I have selected for my resource “dc001 (Microsoft.compute/virtualmachines)” and the cost is around 32p for January 2021.

Now rewind a bit and think how is a VM made up of in Azure such as Server A from above, what components are required at minimum to run Server A? Looking at the diagram below you can see that you have the “Compute” element which refers the size of the VM at the time of running i.e. D2v3. Next you have the “disk/s” where each VM has the OS disk and then any additional data disk you have added for the VM and finally the network card as well as there is potential cost for egress.

If you looked back at my costing diagram above you will see that I have only selected the compute element and have not included any of the disk/s or network card that are associated to the VM. I have selected the other components and you can see there are additional cost associated to the VM when it was not running and these are the disks. The cost is now £2.98 as oppose to just 32p from before because when the VM is not running you still need to pay for the disk themselves. 

After discovering that I could potentially report the costing incorrectly I had to find a solution to be able to report at minimum the three components that built up a VM (Compute, Disk, Network). I turned to using tags to help me label components that built up a VM. I introduced a new tag called “Server” and the value of this tag would be the server name. For each of the resources that was linked to my server “dc001” I added the tag “server” with the value of “dc001”.

As you can see from the chart now I am filtering only by the tag “server” and it has picked up all the resources related to the tag. I don’t need to work out which resources is linked to my VM. You will see the costing is different to the previous chart as I only applied the tagging midway through the month and not at the start. So, it is important to start the tagging early otherwise you will miss some costing if you are using tags as a way to report costing.

I have just shown you how I have tagged some of the core components of a VM in Azure but there could be other elements that you would like to tag such as the snapshots, backups etc which you may want to do show back. Using this way, I have managed to do a more accurate show back cost of a VM as there are other elements such as disk/s which would still cost money even if you weren’t running the server.