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Azure Policy Unveiled: Ignite Your Cloud Management Passion

27 Nov, 2023
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Imagine your company having a multitude of Azure resources, and you want to ensure all of them are compliant with your company’s standards. You could go through each resource and check if they are compliant, but that would be a lot of work. Luckily, Azure Policy can help you with that. Azure Policy is a management tool that helps you enforce and control the settings and configurations of resources within your Azure cloud environment. It enables you to define and enforce rules and policies to ensure that your resources adhere to specific compliance and governance requirements. These policies can cover various aspects, such as security, resource tagging, and naming conventions, helping you maintain a consistent and secure cloud infrastructure. Azure Policy provides a centralized way to monitor and enforce these policies, ensuring that your Azure resources are aligned with your organization’s standards and best practices.

Azure Policy works with definitions to set the conditions and rules to be executed. Definitions dictate the logic, followed by assignments that apply the logic to a scope. A scope can be a management group, subscription, resource group, or resource. When an assignment is made, you can review the compliance of your resources in the compliance dashboard.

When you are ready to look at Azure Policy, you will probably be overwhelmed. Luckily, Microsoft Azure has supplied you with a set of built-in policies you can use to get started. Additionally, when the built-in policies are not sufficient for your needs, you have the option to create custom policies. Below a short summary of the differences:

  • Built-in policy definitions are provided by Microsoft and can be used to audit against your environment.
  • Custom policy definitions are created by you and can be used to audit against your environment.

Important note for built-in policies, they are deployed to the Root Tenant Group and their names are GUIDs. Their display name will explain better what each policy definition does.

Compliance Dashboard Figure 1: Compliance Dashboard

Why would I use it?

Azure Policy is quite powerful and enables your organization to enforce standards and assess compliance. It also helps to bring your resources to compliance through bulk remediation for existing resources and automatic remediation for new resources. But why would you use it? Let’s take a look at some of the benefits of using Azure Policy:

  • Enforce standards: Azure Policy helps to enforce standards and assess compliance. You can also use policies to prevent or (automatically) remediate non-compliant resources.
  • Centralized management: Azure Policy provides a centralized management experience for all your policies. You can create, assign, and manage policies from a single location.
  • Aggregated view: Azure Policy provides an aggregated view of the state of your environment through the compliance dashboard, which shows the overall state of the environment and allows you to view the state of individual resources or policies.
  • Built-in compliance standards: Azure Policy provides built-in compliance standards that can be used to audit against your environment. These standards include CIS, PCI, HIPAA, ISO, NIST, SOC, and more.
  • Bring resources to compliance: Azure Policy helps to bring your resources to compliance through bulk remediation for existing resources and automatic remediation for new resources.
  • Custom compliance standards: Azure Policy provides the ability to create custom compliance standards that can be used to audit against your environment.
  • Audit and remediate: Azure Policy provides the ability to audit and remediate your environment. You can audit your environment by using the audit effect. You can remediate your environment by using the deployIfNotExists effect.
  • Steer user behavior: Azure Policy can be used to steer user behavior by restricting the use of specific resource types. For example, you can restrict the use of public IP’s.

Now we know why we would use Azure Policy, let’s take a look at some of the real life scenario’s that can be solved with Azure Policy:

  • Restricting the location of resources i.e., all resources should be deployed in West Europe or North Europe
  • Enforcing tagging on resources i.e., all resources should have a cost center tag
  • Steer user behavior by restricting the use of specific resource types or SKUs i.e., no use of public IP’s, deny creation of GPU VM’s
  • Enforcing the configuration of specific resource configurations i.e., soft delete on key vaults, or encryption on storage accounts
  • Configure DNS Private Zone settings automatically on private endpoints i.e., configure the DNS Private Zone settings on private endpoints to use the private DNS zone
  • Enforce resource naming for Resource Groups i.e., all resource groups should start with rg-

How do I use Azure Policy?

First, you start with a policy definition that dictates the logic to execute. This can be either a built-in or custom policy. Built-in policies are deployed to the Root Tenant Group and therefore available everywhere in your Management Group and Subscription hierarchy. Custom policies are deployed to a specific scope and therefore only available in that scope or a child scope. The deployment of a policy definition is nothing more than making the policy definition available to be used.

In order to apply the logic of a policy definition to a certain scope, which can be the scope the policy definition was deployed to or any of the child scope in the hierarchy. You will need to create a policy assignment. A policy assignment is the actual assignment of the policy definition to a scope. The policy assignment will evaluate the resources in the scope against the policy definition. The policy assignment will also show the compliance of the resources in the scope.

But what if I want to combine multiple policy definitions and assign it as part of a single policy? This is where policy initiatives come in. Policy initiatives are a collection of one or more policy definitions. Like policy definitions, these are deployed to a specific scope and can be assigned to a scope. The assignment of a policy initiative is the same as the assignment of a policy definition.

Policy Deployment Scope and Assignment

Figure 2: Policy Deployment Scope and Assignment

Policy Definitions

A policy definition is a JSON document that defines the logic of the policy. Let’s create a policy definition together.

  • Name: The name of the policy definition.
  • Description: A description of the policy definition.
  • PolicyRule: The policy rule that defines the logic of the policy definition.
  • Metadata: Metadata about the policy definition.
  • Parameters: Parameters that can be used in the policy rule.

Name

The name of the policy definition. The name is used to identify the policy definition. The name must be unique within the scope of the policy definition.

Description

A description of the policy definition. The description is used to describe the policy definition. The description is optional.

PolicyRule

Policy definitions use policy rules to dictate the logic to perform or validate. These rules are built using an if-then construct. The IF part contains the resource(s) to search for, the THEN part contains action to take.

The IF-part of the policy rules

The IF parts contain multiple options to identify the scope for the policy. These use logical operators to check the conditions. Within the logical operators, conditions are used to determine if the policy should execute the THEN part. You can use the following operators:

  • not – the conditions should not be true (inverting the result).
  • allOf – each condition in the block should be true.
  • anyOf – any condition in the block should be true.

With these logical operators, you are flexible in terms of identifying which resources should be used in the specific policy. You can even use nested operators. The logical operators use conditions to identify when to perform the THEN part of the policy. Conditions are always described with a field value and an option that returns a true or false result. Possible options are:

  • equals – true if the field value matches the equals value.
  • notEquals – true if the field value does not match the notEquals value.
  • exists – true if the field value exists.
  • in – true if the field value is in the list of values.

The field values can contain a multitude of different options. Let’s go over some of the commonly used options:

  • Type indicates the actual resource type (i.e., “Microsoft.KeyVault/vaults”)
  • Location indicates the resource location (i.e., “WestEurope”)
  • Id indicates the actual resource ID of an Azure resource (see properties on a resource to view/copy the resource ID)
  • Aliases can be used to access a property of a resource type.
  • And many more.
The THEN-part of policy rules

For the THEN part, Azure Policy uses an effect to identify the action to be taken when the conditions of the definition or initiative are non-compliant. Eight types of effects are available:

  • Deny will ensure the non-compliant resource cannot be created or deployed.
  • Audit will audit the resources’ compliance and show the status in the compliance dashboard.
  • DeployIfNotExists will deploy the configuration specified in the definition to the resource if the configuration does not exist.
  • AuditIfNotExists will audit the configuration specified in the definition and only report if the resource configuration does not exist.
  • Modify is used to add, update, or remove properties or tags on a subscription or resource during creation or update.
  • Append is used to add more fields to the requested resource during creation or update.
  • Manual enables you to self-attest the compliance of resources or scopes.
  • Disabled means the logic in the definition will effectively do nothing and is turned off.

Metadata

This is metadata about the policy definition. The metadata is used to provide additional information about the policy definition. The metadata is optional. Common metadata properties are:

  • Category: The category of the policy definition.
  • Version: The version of the policy definition.
  • Deprecated: Indicates if the policy definition is deprecated.
  • Preview: Indicates if the policy definition is in preview.

Parameters

Parameters are optional. They can be used to make the policy definition more flexible. Parameters are defined in the parameters section of the policy definition. Parameters are referenced in the policy rule by using the following syntax: [parameters('parameterName')]. Parameters will be prompted for when assigning the policy definition.

Result

Let’s take a look at an example of a policy definition. The following policy definition is used to audit the use of the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property. The policy definition is named audit-storage-account-network-acl-default-action and has the following properties:

  • Description: Audit the use of the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property.
  • PolicyRule: If the type of the resource is Microsoft.Storage/storageAccounts and the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property is not equal to Deny, then audit the resource.
  • Metadata: The category is Storage and the version is 1.0.0.

{
  "properties": {
    "displayName": "Audit storage account network ACL default action",
    "description": "Audit the use of the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property.",
    "mode": "Indexed",
    "policyRule": {
      "if": {
        "allOf": [
          {
            "field": "type",
            "equals": "Microsoft.Storage/storageAccounts"
          },
          {
            "field": "Microsoft.Storage/storageAccounts/networkAcls/defaultAction",
            "notEquals": "Deny"
          }
        ]
      },
      "then": {
        "effect": "audit"
      }
    },
    "metadata": {
      "category": "Storage",
      "version": "1.0.0"
    }
  }
}

Examples

  • I only want to allow resources to be deployed in the West Europe region. This can be achieved by using the DENY effect, it will verify the condition and it will DENY the deployment if the condition returns as true.In this case, IF the location is not equal to WestEurope returns true THEN we DENY the deployment.
    
    "policyRule": {
      "if": {
        "not": {
          "field": "location",
          "equals": "WestEurope"
        }
      },
      "then": {
        "effect": "Deny"
      }
    }
    
  • I want to always add soft delete on key vaults on creation. For this scenario we can use APPEND as the effect, we will verify if the condition is true and then we will append a specific configuration/property.In this case, we verify IF the type of the resource is a Key Vault and if the soft delete option is not true. When the conditions have been verified, we will THEN APPEND the soft delete option.
    
    "policyRule": {
      "if": {
        "anyOf": [
          {
            "allOf": [
              {
                "field": "type",
                "equals": "Microsoft.KeyVault/vaults"
              },
              {
                "field": "Microsoft.KeyVault/vaults/enableSoftDelete",
                "notEquals": true
              }
            ]
          }
        ]
      },
      "then": {
        "effect": "append",
        "details": [
          {
            "field": "Microsoft.KeyVault/vaults/enableSoftDelete",
            "value": true
          }
        ]
      }
    }
    

How do I deploy policy definitions?

As always with cloud resources, the preferable way to deploy them is using Infrastructure as Code (IaC). Azure Policy definitions can be deployed using ARM templates, Azure CLI, Bicep, Terraform, or PowerShell. The following example shows how to deploy the policy definition using a PowerShell script:


New-AzPolicyDefinition -Name 'audit-storage-account-network-acl-default-action' -DisplayName 'Audit storage account network ACL default action' -Description 'Audit the use of the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property.' -Policy 'audit-storage-account-network-acl-default-action.json' -Mode All

Important to note is the PowerShell cmdlet uses the -Policy argument to define the Policy Rule. Each of the important parts of the policy definition is defined in the cmdlet.

File: audit-storage-account-network-acl-default-action.json:


{
  "if": {
    "anyOf": [
      {
        "allOf": [
          {
            "field": "type",
            "equals": "Microsoft.KeyVault/vaults"
          },
          {
            "field": "Microsoft.KeyVault/vaults/enableSoftDelete",
            "notEquals": true
          }
        ]
      }
    ]
  },
  "then": {
    "effect": "append",
    "details": [
      {
        "field": "Microsoft.KeyVault/vaults/enableSoftDelete",
        "value": true
      }
    ]
  }
}

Policy Initiatives

A policy initiative is a collection of one or more policy definitions. Policy initiatives are used to group policy definitions together. This can be useful when you want to assign multiple policy definitions to a scope. Instead of assigning each policy definition individually, you can assign the policy initiative. The policy initiative will then assign all the policy definitions that are part of the policy initiative. Let’s create a policy initiative together.


{
  "properties": {
    "displayName": "Audit storage account network ACL",
    "description": "Audit the use of the Microsoft.Storage/storageAccounts/networkAcls/defaultAction property and the Microsoft.Storage/storageAccounts/networkAcls/bypass property.",
    "metadata": {
      "category": "Storage",
      "version": "1.0.0"
    },
    "policyDefinitions": [
      {
        "policyDefinitionId": "/providers/Microsoft.Authorization/policyDefinitions/audit-storage-account-network-acl-default-action",
        "parameters": {}
      },
      {
        "policyDefinitionId": "/providers/Microsoft.Authorization/policyDefinitions/audit-storage-account-network-acl-bypass",
        "parameters": {}
      }
    ]
  }
}

How do I deploy policy initiatives?

As always with cloud resources, the preferred way to deploy them is using Infrastructure as Code (IaC). Azure Policy initiatives can be deployed using ARM templates, Bicep, Terraform, or PowerShell. The following example shows how to deploy the policy initiative using Powershell:


# Create a new policy initiative using the policy definitions supplied in the audit-storage-account-network-acl.json file
New-AzPolicySetDefinition -Name 'audit-storage-account-network-acl' -PolicyDefinition 'audit-storage-account-network-acl.json'

File: audit-storage-account-network-acl.json:


[
  {
    "policyDefinitionId": "/providers/Microsoft.Authorization/policyDefinitions/audit-storage-account-network-acl-default-action",
    "parameters": {}
  },
  {
    "policyDefinitionId": "/providers/Microsoft.Authorization/policyDefinitions/audit-storage-account-network-acl-bypass",
    "parameters": {}
  }
]

Policy Assignments

A policy assignment is the actual assignment of the policy definition or policy initiative to a scope. The policy assignment will evaluate the resources in the scope against the policy definition or policy initiative. The policy assignment will also show the compliance of the resources in the scope. Let’s create a policy assignment together, using PowerShell.


# Get the subscription data
$Subscription = Get-AzSubscription -SubscriptionName 'Subscription01'
# Get the policy definition data
$Policy = Get-AzPolicyDefinition -Name 'audit-storage-account-network-acl-default-action'
# Create the policy assignment using the retrieved subscription and policy definition data
New-AzPolicyAssignment -Name 'audit-storage-account-network-assignment' -PolicyDefinition $Policy -Scope "/subscriptions/$($Subscription.Id)"

How can I see my resource compliance?

After you have created and assigned your policies, you can view the compliance of your resources. The compliance dashboard provides an aggregated view of the state of your environment. It shows the overall state of the environment and allows you to view the state of individual resources or policies. The compliance dashboard can be found in the Azure Portal under All services > Policy > Compliance.

Figure 3: Compliance Dashboard

Figure 3: Compliance Dashboard

Regulatory compliance

In order to view regulatory compliance, Microsoft Azure also uses Azure Policy to report on the compliance state of the regulatory compliance standards you have assigned. Whenever you select a regulatory compliance standard, Azure Policy will automatically create a policy assignment to audit the compliance state of the regulatory compliance standard. Azure Defender for Cloud also uses the input from Azure Policy to show recommendations in the Azure Portal.

To view the compliance state of the regulatory compliance standards you have assigned, you can use the regulatory compliance dashboard. The regulatory compliance dashboard can be found in the Azure Portal under All services > Microsoft Defender for Cloud > Regulatory compliance.

Regulatory Compliance Dashboard

Figure 4: Regulatory Compliance Dashboard

How does remediation work?

Remediation is the process of bringing a non-compliant resource into compliance. When remediation is done manually, you can trigger the remediation from the compliance dashboard. When remediation should be done automatically, which is only possible when using the DeployIfNotExists or Modify effect, you can configure the policy to automatically remediate non-compliant resources. In order for the policy to remediate automatically, it will use a managed identity. This managed identity should be supplied in the policy assignment. In order to use the remediation, you need to specify, in the policy definition, which role the managed identity should have on the resource. The policy assignment will start the deployment to perform the remediation task. When using the DeployIfNotExists effect, the deployment will be visible in the deployment dashboard so you can track and troubleshoot the deployment.

Automatic remediation

Let’s use a built-in policy definition to show how automatic remediation works. The built-in policy definition is named Add or replace a tag on resource groups and has the following PolicyRule logic:


{
  "if": {
    "allOf": [
      {
        "field": "type",
        "equals": "Microsoft.Resources/subscriptions/resourceGroups"
      },
      {
        "field": "[concat('tags[', parameters('tagName'), ']')]",
        "notEquals": "[parameters('tagValue')]"
      }
    ]
  },
  "then": {
    "effect": "modify",
    "details": {
      "roleDefinitionIds": [
        "/providers/microsoft.authorization/roleDefinitions/b24988ac-6180-42a0-ab88-20f7382dd24c"
      ],
      "operations": [
        {
          "operation": "addOrReplace",
          "field": "[concat('tags[', parameters('tagName'), ']')]",
          "value": "[parameters('tagValue')]"
        }
      ]
    }
  }
}

The policy definition will check if the resource type is a resource group and if the tag is not equal to the specified value. If the conditions are true, the policy will modify the resource group and add or replace the specified tag.

As described earlier, we should create a policy assignment to make this logic active on a certain scope. Let’s create a policy assignment together, using PowerShell.


# Get the subscription data
$Subscription = Get-AzSubscription -SubscriptionName 'Subscription01'
# Get the policy definition data, using a Where-Object, since built-in policies are named with a GUID
$Policy = Get-AzPolicyDefinition | Where-Object {$_.Properties.DisplayName -eq 'Add or replace a tag on resource groups'}
# Define the parameters for the policy assignment to pass to the -PolicyParameterObject parameter
$parameters = @{'tagName'='Environment';'tagValue'='Production'}
# Create the policy assignment using the retrieved subscription and policy definition data
New-AzPolicyAssignment -Name 'add-tag-resource-group' -PolicyDefinition $Policy -Scope "/subscriptions/$($Subscription.Id)" -IdentityType 'SystemAssigned' -Location 'WestEurope' -PolicyParameterObject $parameters

Policy Assignment - Remediation

Figure 5: Policy Assignment – Remediation

The policy assignment will automatically remediate the resource group and add or replace the specified tag. The deployment will be visible in the deployment dashboard so you can track and troubleshoot the deployment.

So what happens when you create a resource group without the specified tag? Let’s try it out!


# Set the subscription context
Set-AzContext -Subscription 'Subscription01'
# Create a new resource group without the specified tag
New-AzResourceGroup -Name 'rg-remediation-test' -Location 'WestEurope'

Result of Resource Group

Figure 6: Result of Resource Group

As you can see, the resource group is created without the specified tag and the output already shows the policy assignment has remediated the resource group. When we check the resource group, we can see the tag is added.

Tag Present

Figure 7: Tag Present

Manual remediation

Let’s use the same example as with the automatic remediation, but we have now changed the policy to seek the TagName:Demo with a TagValue:ManualRemediation.


# Get the subscription data
$Subscription = Get-AzSubscription -SubscriptionName 'Subscription01'
# Get the policy definition data, using a Where-Object, since built-in policies are named with a GUID
$Policy = Get-AzPolicyDefinition | Where-Object {$_.Properties.DisplayName -eq 'Add or replace a tag on resource groups'}
# Define the parameters for the policy assignment to pass to the -PolicyParameterObject parameter
$parameters = @{'tagName'='Demo';'tagValue'='ManualRemediation'}
# Create the policy assignment using the retrieved subscription and policy definition data
New-AzPolicyAssignment -Name 'add-tag-resource-group' -PolicyDefinition $Policy -Scope "/subscriptions/$($Subscription.Id)" -IdentityType 'SystemAssigned' -Location 'WestEurope' -PolicyParameterObject $parameters

Policy Assignment - Non CompliantFigure 8: Policy Assignment – Non Compliant

Since the policy is not compliant, we can manually remediate the resource group by clicking on the Create Remediation Task button in the assignment page on the subscription.

Manual Remediation Input

Figure 9: Manual Remediation Input

After the remediation task has been created, we can see the task in the remediation tasks overview. And you should even see a completed remediation task.

Completed Remediation

Figure 10: Completed Remediation

Exemptions

Sometimes you want to exclude certain resources from being evaluated by a policy. This can be done by using exemptions. Exemptions can be made on policy assignments and on individual resources. Exemptions can be made for a specific amount of time or indefinitely. Exemptions can be made for the following reasons:

  • Mitigation: The resource is already mitigated.
  • False positive: The resource is evaluated as non-compliant but it is compliant.
  • Business justification: The resource is evaluated as non-compliant but it is compliant for business reasons.
  • Waiver: The resource is evaluated as non-compliant but it is compliant for legal reasons.

How do I create an exemption?

Exemptions can be created using the Azure Portal, PowerShell, Azure CLI, or REST API. Let’s create an exemption using PowerShell.


# Get the subscription data
$Subscription = Get-AzSubscription -SubscriptionName 'Subscription01'
# Get the policy assignment data
$PolicyAssignment = Get-AzPolicyAssignment -Name 'add-tag-resource-group' -Scope "/subscriptions/$($Subscription.Id)"
# Create the exemption
New-AzPolicyExemption -Name 'exemption-add-tag-resource-group' -PolicyAssignment  $PolicyAssignment -ExemptionCategory 'Waiver' -ExpiresOn (Get-Date).AddDays(7)

Exemption CreatedFigure 11: Exemption Created

Now what?

Now that you know what Azure Policy is and how to use it, you can start using it in your own environment. Start with the built-in policies and see if they fit your needs. If they don’t, you can always create custom policies.

If you want to explore and view anything policy-related in the Azure Portal, simply go to All services > Policy. Here you can view the compliance dashboard, policy definitions, policy initiatives, policy assignments, and exemptions.

If you want to know which Azure Policies are available built-in, AzAdvertizer is a great resource to view all the built-in policies.

 

 

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