Azure Policy definitions denyAction effect

The denyAction effect is used to block requests based on intended action to resources at scale. The only supported action today is DELETE. This effect and action name helps prevent any accidental deletion of critical resources.

DenyAction evaluation

When a request call with an applicable action name and targeted scope is submitted, denyAction prevents the request from succeeding. The request is returned as a 403 (Forbidden). In the portal, the Forbidden can be viewed as a deployment status that was prevented by the policy assignment.

Microsoft.Authorization/policyAssignments, Microsoft.Authorization/denyAssignments, Microsoft.Blueprint/blueprintAssignments, Microsoft.Resources/deploymentStacks, Microsoft.Resources/subscriptions, and Microsoft.Authorization/locks are all exempt from denyAction enforcement to prevent lockout scenarios.

Subscription deletion

Policy doesn't block removal of resources that happens during a subscription deletion.

Resource group deletion

Policy evaluates resources that support location and tags against denyAction policies during a resource group deletion. Only policies that have the cascadeBehaviors set to deny in the policy rule block a resource group deletion. Policy doesn't block removal of resources that don't support location and tags nor any policy with mode:all.

Cascade deletion

Cascade deletion occurs when deleting of a parent resource is implicitly deletes all its child and extension resources. Policy doesn't block removal of child and extension resources when a delete action targets the parent resources. For example, Microsoft.Insights/diagnosticSettings is an extension resource of Microsoft.Storage/storageaccounts. If a denyAction policy targets Microsoft.Insights/diagnosticSettings, a delete call to the diagnostic setting (child) fails, but a delete to the storage account (parent) implicitly deletes the diagnostic setting (extension).

This table describes if a resource is protected from deletion given the resource applicable to the assigned denyAction policy and the targeted scope of the DELETE call. In the context of this table, an indexed resource is one that supports tags and locations and a non-indexed resource is one that doesn't support tags or locations. For more information on indexed and non-indexed resources, go to definition mode. Child resources are resources that exist only within the context of another resource. For example, a virtual machines extension resource is a child of the virtual machine, which is the parent resource.

Entity being deleted	Entity applicable to policy conditions	Action taken
Resource	Resource	Protected
Subscription	Resource	Deleted
Resource group	Indexed resource	Depends on cascadeBehaviors
Resource group	Non indexed resource	Deleted
Child resource	Parent resource	Parent is protected; child is deleted
Parent resource	Child resource	Deleted

DenyAction properties

The details property of the denyAction effect has all the subproperties that define the action and behaviors.

• actionNames (required)
  • An array that specifies what actions to prevent from being executed.
  • Supported action names are: delete.
• cascadeBehaviors (optional)
  • An object that defines which behavior is followed when a resource is implicitly deleted when a resource group is removed.
  • Only supported in policy definitions with mode set to indexed.
  • Allowed values are allow or deny.
  • Default value is deny.

DenyAction example

Example: Deny any delete calls targeting database accounts that have a tag environment that equals prod. Since cascade behavior is set to deny, block any DELETE call that targets a resource group with an applicable database account.

JSON

{
  "if": {
    "allOf": [
      {
        "field": "type",
        "equals": "Microsoft.DocumentDb/accounts"
      },
      {
        "field": "tags.environment",
        "equals": "prod"
      }
    ]
  },
  "then": {
    "effect": "denyAction",
    "details": {
      "actionNames": [
        "delete"
      ],
      "cascadeBehaviors": {
        "resourceGroup": "deny"
      }
    }
  }
}

Next steps

• Review examples at Azure Policy samples.
• Review the Azure Policy definition structure.
• Understand how to programmatically create policies.
• Learn how to get compliance data.
• Learn how to remediate non-compliant resources.
• Review Azure management groups.