Configure managed identities for Azure resources on an Azure VM using templates

Article
03/16/2023
6 minutes to read

Managed identities for Azure resources is a feature of Azure Active Directory. Each of the Azure services that support managed identities for Azure resources are subject to their own timeline. Make sure you review the availability status of managed identities for your resource and known issues before you begin.

Managed identities for Azure resources provide Azure services with an automatically managed identity in Azure Active Directory. You can use this identity to authenticate to any service that supports Azure AD authentication, without having credentials in your code.

In this article, using the Azure Resource Manager deployment template, you learn how to perform the following managed identities for Azure resources operations on an Azure VM:

Prerequisites

If you're unfamiliar with using Azure Resource Manager deployment template, check out the overview section. Be sure to review the difference between a system-assigned and user-assigned managed identity.
If you don't already have an Azure account, sign up for a free account before continuing.

Azure Resource Manager templates

As with the Azure portal and scripting, Azure Resource Manager templates allow you to deploy new or modified resources defined by an Azure resource group. Several options are available for template editing and deployment, both local and portal-based, including:

Using a custom template from the Azure Marketplace, which allows you to create a template from scratch, or base it on an existing common or quickstart template.
Deriving from an existing resource group, by exporting a template from either the original deployment, or from the current state of the deployment.
Using a local JSON editor (such as VS Code), and then uploading and deploying by using PowerShell or CLI.
Using the Visual Studio Azure Resource Group project to both create and deploy a template.

Regardless of the option you choose, template syntax is the same during initial deployment and redeployment. Enabling a system or user-assigned managed identity on a new or existing VM is done in the same manner. Also, by default, Azure Resource Manager does an incremental update to deployments.

System-assigned managed identity

In this section, you will enable and disable a system-assigned managed identity using an Azure Resource Manager template.

Enable system-assigned managed identity during creation of an Azure VM or on an existing VM

To enable system-assigned managed identity on a VM, your account needs the Virtual Machine Contributor role assignment. No other Azure AD directory role assignments are required.

Whether you sign in to Azure locally or via the Azure portal, use an account that is associated with the Azure subscription that contains the VM.
To enable system-assigned managed identity, load the template into an editor, locate the Microsoft.Compute/virtualMachines resource of interest within the resources section and add the "identity" property at the same level as the "type": "Microsoft.Compute/virtualMachines" property. Use the following syntax:
```
"identity": {
    "type": "SystemAssigned"
},
```

When you're done, the following sections should be added to the resource section of your template and it should resemble the following:

 "resources": [
     {
         //other resource provider properties...
         "apiVersion": "2018-06-01",
         "type": "Microsoft.Compute/virtualMachines",
         "name": "[variables('vmName')]",
         "location": "[resourceGroup().location]",
         "identity": {
             "type": "SystemAssigned",
             }                        
     }
 ]

Assign a role the VM's system-assigned managed identity

After you enable a system-assigned managed identity on your VM, you may want to grant it a role such as Reader access to the resource group in which it was created. You can find detailed information to help you with this step in the Assign Azure roles using Azure Resource Manager templates article.

Disable a system-assigned managed identity from an Azure VM

To remove system-assigned managed identity from a VM, your account needs the Virtual Machine Contributor role assignment. No other Azure AD directory role assignments are required.

Whether you sign in to Azure locally or via the Azure portal, use an account that is associated with the Azure subscription that contains the VM.
Load the template into an editor and locate the Microsoft.Compute/virtualMachines resource of interest within the resources section. If you have a VM that only has system-assigned managed identity, you can disable it by changing the identity type to None.

Microsoft.Compute/virtualMachines API version 2018-06-01

If your VM has both system and user-assigned managed identities, remove SystemAssigned from the identity type and keep UserAssigned along with the userAssignedIdentities dictionary values.

Microsoft.Compute/virtualMachines API version 2018-06-01

If your apiVersion is 2017-12-01 and your VM has both system and user-assigned managed identities, remove SystemAssigned from the identity type and keep UserAssigned along with the identityIds array of the user-assigned managed identities.

The following example shows you how to remove a system-assigned managed identity from a VM with no user-assigned managed identities:

{
    "apiVersion": "2018-06-01",
    "type": "Microsoft.Compute/virtualMachines",
    "name": "[parameters('vmName')]",
    "location": "[resourceGroup().location]",
    "identity": {
        "type": "None"
    }
}

User-assigned managed identity

In this section, you assign a user-assigned managed identity to an Azure VM using Azure Resource Manager template.

Note

To create a user-assigned managed identity using an Azure Resource Manager Template, see Create a user-assigned managed identity.

Assign a user-assigned managed identity to an Azure VM

To assign a user-assigned identity to a VM, your account needs the Managed Identity Operator role assignment. No other Azure AD directory role assignments are required.

Under the resources element, add the following entry to assign a user-assigned managed identity to your VM. Be sure to replace <USERASSIGNEDIDENTITY> with the name of the user-assigned managed identity you created.

Microsoft.Compute/virtualMachines API version 2018-06-01

If your apiVersion is 2018-06-01, your user-assigned managed identities are stored in the userAssignedIdentities dictionary format and the <USERASSIGNEDIDENTITYNAME> value must be stored in a variable defined in the variables section of your template.

 {
     "apiVersion": "2018-06-01",
     "type": "Microsoft.Compute/virtualMachines",
     "name": "[variables('vmName')]",
     "location": "[resourceGroup().location]",
     "identity": {
         "type": "userAssigned",
         "userAssignedIdentities": {
             "[resourceID('Microsoft.ManagedIdentity/userAssignedIdentities/',variables('<USERASSIGNEDIDENTITYNAME>'))]": {}
         }
     }
 }

Microsoft.Compute/virtualMachines API version 2017-12-01

If your apiVersion is 2017-12-01, your user-assigned managed identities are stored in the identityIds array and the <USERASSIGNEDIDENTITYNAME> value must be stored in a variable defined in the variables section of your template.

{
    "apiVersion": "2017-12-01",
    "type": "Microsoft.Compute/virtualMachines",
    "name": "[variables('vmName')]",
    "location": "[resourceGroup().location]",
    "identity": {
        "type": "userAssigned",
        "identityIds": [
            "[resourceID('Microsoft.ManagedIdentity/userAssignedIdentities/',variables('<USERASSIGNEDIDENTITYNAME>'))]"
        ]
    }
}