Azure Policy is a powerful tool for Azure Governance. With Azure Policy we can define rules for all Azure Subscriptions the we manage. We can use this rules for simple limitation actions, like permitting only specific VM Series and Sizes that can be created and also more complex rule sets that helps you standardize the whole Azure deployment. At my previous posts, we learned How to limit the Azure VM Sizes and How to enforce tags for resources creation
At the current post we will learn how to use Azure Policy to have a compliance report for our deployment. We will learn this by using an example. Then we will create two Virtual Networks and we will add a Network Security Group only to the first one. Finally we will use the Policy to audit whether the Subnets have assigned the NSG or Not.
First we need two Virtual Networks. You can create the Virtual Networks using the Azure Portal or using ARM template, like mine from my Github account: https://github.com/proximagr/ARMTemplates/blob/master/2vnets.json
After applying the template you will have two VNETs like that:
Then we will a Network Security Group (NSG) only to the MyVNET01 Virtual Network. Again using Azure Portal, PowerShell or my ARM Template for NSG
Assign the NSG to the MyVNET01 VIrtual Network
Add the Policy
Go to Azure Policy -> Definitions and click the “+ Policy definition” to create a new policy definition.
At the New Policy definition page, select the subscription (location) that the policy will be saved, then add a name. in this case we will use the sample policy template from Microsoft docs so I will add the same name.
Copy the policy Json text from https://docs.microsoft.com/en-us/azure/governance/policy/samples/nsg-on-subnet and paste it at the POLICY RULE below and Save.
At the “effect” part of the Json, change the “deny” to “audit”.
If you search for “NSG” you will see our new policy definition, ready to be assigned.
Click on the definition’s name to open it and press Assign.
I will just target the “ComplianceReport” Resource Group
At the parameters, I added the Resource ID of the NSG, “MyNSG01”
Evaluate the results
To check the compliance, go to Policy – Compliance page and search for nsg. You have to wait for about 15 minutes for the compliance policy to evaluate the resources.
If you search “nsg” you will see that the “Audit NSG on Subnet” policy is 50% compliant. Click on the policy’s name to view more details.
The assignment details page will open where we can see what resources are not compliant.
Click on the three dots (…) next to the non-compliant subnet and select “view compliance details” to check why this resource is not compliant.
The compliance details reports that the value is null and what the required (target) value must be.
If you want to trigger an on-demand compliance check, you need to make a POST request. You can follow my post Validate Azure Resource Move with Postman to create the access Token and then use it to make a POST request to the Resource Group sung this POST:
Pantelis Apostolidis is a Sr. Cloud Solutions Architect professional at Office Line SA and a recognized Microsoft Azure MVP. For the last 15 years, Pantelis has been involved to major cloud projects in Greece and abroad, helping companies to adopt and deploy cloud technologies, driving business value. He is entitled to a lot of Microsoft Expert Certifications, demonstrating his proven experience in delivering high quality solutions. He is an author, blogger and he is acting as a spokesperson for conferences, workshops and webinars. He is also an active member of several communities as a moderator in azureheads.gr and autoexec.gr. Follow him on Twitter @papostolidis.