Secure Your Azure Batch: Leverage Managed Identities for Enhanced Security

Table of Contents

This article explains how to use managed identities in a Microsoft Azure Batch account or a batch pool. It discusses when you should configure managed identities at the account level versus the pool level. The article also outlines different behavior scenarios because the use of managed identities can lead to confusion in some failure situations. Implementing managed identities significantly enhances the security posture of your Azure Batch workloads by removing the need to manage credentials directly.

Prerequisites¶

Before you begin configuring managed identities for your Azure Batch setup, ensure you have the following resources readily available. These prerequisites provide the foundational elements needed to proceed with the steps outlined in this guide. Having these components configured correctly will streamline the implementation process.

• An Azure Batch account.
• An Azure Storage account.
• Postman (or a similar tool for testing HTTP requests).

Set Up Your Storage Account to Use with Your Batch Account¶

To utilize managed identities within your Batch account, it is essential to first configure your storage account to function as your Batch account’s autostorage. This designated autostorage is used by Azure Batch to store vital components like application packages and task resource files, crucial for job execution. Linking the storage account to your Batch account is the initial step in this configuration process. Furthermore, you must explicitly set the authentication mode for this autostorage account to use Batch Account Managed Identity.

This ensures that the Batch account itself can securely access the storage resources without relying on shared keys or connection strings. Follow these steps in the Azure portal to complete this necessary setup. Proper configuration here is foundational for leveraging managed identities at the Batch account level.

To complete this setup, follow these steps:

1. In the Azure portal, search for and select Batch accounts.
2. In the list of batch accounts, select the name of your specific batch account.
3. In the navigation pane of the batch account, locate the Settings heading, and then select Storage account.
4. Under the STORAGE ACCOUNT INFORMATION section, select Select a storage account. Choose the storage account you intend to use as autostorage for this Batch account.
5. After successfully selecting your storage account, return to the STORAGE ACCOUNT INFORMATION section. Change the Authentication mode field from its default setting to Batch Account Managed Identity.

Set Up Managed Identity in Your Batch Account¶

Configuring a managed identity directly on an Azure Batch account grants the Batch service itself permission to authenticate to other Azure services. This capability is distinct from granting authentication permissions to the individual batch nodes or the virtual machines within a batch pool. Setting up a managed identity at the account level is primarily for operations managed by the Batch service plane, such as accessing the linked autostorage account for application package management.

When setting up managed identity in your Batch account, you have two primary options to choose from based on your requirements. You can enable the system-assigned managed identity, which is tied directly to the lifecycle of the Batch account. Alternatively, for more granular control and reusability, you can create a separate user-assigned managed identity and associate it with the Batch account. Choosing the appropriate identity type depends on your organizational policies and specific use case needs.

To set up managed identity in your batch account, follow these steps:

1. In the Azure portal, search for and select Batch accounts.
2. In the list of batch accounts, select the name of your batch account.
3. In the navigation pane of the batch account, locate the Settings heading, and then select Identity.
4. In the Identity type heading, select either System assigned (to enable a system-assigned managed identity unique to this Batch account) or User assigned (to associate a pre-created user-assigned managed identity).
5. After completing this configuration step, navigate back to the overview page of your batch account. In the Essentials section of the page, select JSON View. The JSON representation of the managed identity configuration will be displayed, confirming the identity type and details in one of the following formats, depending on your selection:

System-assigned managed identity:

    "identity": {
        "principalId": "<principal-guid>",
        "tenantId": "<tenant-guid>",
        "type": "SystemAssigned"
    }

User-assigned managed identity:

    "identity": {
        "type": "UserAssigned",
        "userAssignedIdentities": {
            "/subscriptions/<subscription-guid>/resourceGroups/<resource-group-name>/providers/Microsoft.ManagedIdentity/userAssignedIdentities/<user-assigned-identity-name>": {
                "principalId": "<principal-guid>",
                "clientId": "<client-guid>"
            }
        }
    }

Use a Managed Identity to Access Your Autostorage Account¶

The managed identity feature configured for your Batch account is employed for specific service-level tasks, such as the process of uploading an application package to your Batch account. When you upload an application package, for example, by navigating to your Batch account overview page in the Azure portal, selecting Applications > Add, and following the portal instructions, Azure Batch stores this package in its designated autostorage account. Since you previously set the authentication mode of the Batch account to Batch Account Managed Identity, the system automatically retrieves the necessary credentials from the Batch account’s managed identity to securely access the autostorage account for the upload operation.

It is crucial to verify that the managed identity associated with your Batch account possesses sufficient permissions on the configured autostorage account to perform required operations like uploading. Insufficient permissions will prevent the Batch service from interacting correctly with the storage. To check for these necessary permissions and troubleshoot potential access issues, follow these steps within the Azure portal. Ensuring the correct Role-Based Access Control (RBAC) roles are assigned is key.

To check for these permissions, follow these steps:

1. In the Azure portal, search for and select Storage accounts.
2. In the list of storage accounts, select the name of your autostorage account that is linked to the Batch account.
3. In the navigation pane of the storage account, select Access Control (IAM). This section allows you to manage who has access to the storage account and what they can do.
4. On the Access Control (IAM) page, select the Check access button located at the top.
5. In the Check access pane that appears, select the Managed identity option as the principal type you want to check permissions for.
6. In the Managed identity field, select the specific system-assigned or user-assigned managed identity that you configured for your Batch account.
7. Review the Current role assignments tab. Check whether there is an assigned role that provides sufficient permissions, such as Storage Blob Data Contributor or Owner, to allow the Batch account to upload application packages. If an appropriate role assignment is missing, you will encounter an error when attempting to upload application packages. The following error message typically appears in your Azure portal notifications:

Upload Error for .zip

File Upload encountered an unexpected error during upload.

If you encounter this upload error, further investigation can be done by examining the HTTP Archive (.har) file generated during the failed upload request. Look for a POST request with a name prefix like batch (e.g., batch?api-version=2020-06-01), which should show an HTTP status of 200. Within the payload of this request, you will find the actual PUT request that was sent to your Batch account endpoint. The response to this PUT request will reveal an HTTP status of 409 Conflict. The full error response within the HAR file will resemble the following text, clearly indicating a permission issue:

{responses: [{name: "<response-guid>", httpStatusCode: 409,...}]}
  {responses: [{name: "<response-guid>", httpStatusCode: 409,...}]}
    0: {name: "<response-guid>", httpStatusCode, 409,...}
      content: {error: {code: "AutoStorageNoPermission",...}}
        error: {code: "AutoStorageNoPermission",...}
          code: "AutoStorageNoPermission"
          message: "The managed identity does not have permission to access auto storage account. Please use Azure RBAC to assign the managed identity access to auto storage."
          target: "BatchAccount"
        contentLength: 318

This error message explicitly states that the system-assigned or user-assigned managed identity configured for your Batch account lacks the necessary permissions to perform actions on the linked autostorage account. Remediation involves assigning the correct Azure RBAC role to the managed identity on the storage account resource.

Use a Managed Identity to Access Your Key Vault¶

Managed identities associated with your Azure Batch account or pool can also be leveraged to securely access secrets, keys, or certificates stored in Azure Key Vault. This is particularly useful if your Batch tasks require sensitive configuration information or credentials to interact with other services. By using a managed identity, you avoid embedding secrets directly within your task scripts or application code, significantly improving security. For detailed guidance on configuring and utilizing managed identities to access Azure Key Vault in conjunction with Azure Batch, refer to documentation specifically covering customer-managed keys and managed identity integration. This pattern is a best practice for handling sensitive data in automated workflows.

Set Up Managed Identity in Your Batch Pool¶

If your goal is to enable the individual Azure Batch nodes (the virtual machines where your tasks run) to securely access other Azure resources, you must configure a managed identity at the Azure Batch pool level. This is distinct from the Batch account managed identity, which serves the Batch service itself. A pool-level managed identity is assigned to the VMs in the pool and allows tasks running on those VMs to authenticate to services like Azure Storage, Azure SQL Database, or Key Vault using the identity of the VM, without requiring embedded credentials.

When the authentication mode of the autostorage account is set to Batch Account Managed Identity, surprisingly, the Azure Batch nodes still receive managed identity tokens related to the pool’s identity. The nodes then use these managed identity tokens to authenticate through Microsoft Entra authentication by leveraging the Azure Instance Metadata Service (IMDS), which is accessible from within the VM. This allows tasks on the nodes to download application packages or resource files from autostorage.

It is important to note that the Azure Batch pool currently supports only the user-assigned version of managed identity for node-level authentication. Therefore, you are required to create a user-assigned managed identity beforehand in the same Microsoft Entra tenant as your Azure Batch account. Furthermore, you must grant this user-assigned managed identity appropriate permissions on the data plane of the target Azure resource, such as a storage account, using Azure Role-Based Access Control (RBAC). For accessing blobs in a storage account, roles like “Storage Blob Data Reader” or “Storage Blob Data Contributor” would be necessary.

Associate Managed Identity to the Node that Accesses the Autostorage Account¶

For the user-assigned identity that the compute nodes within a pool will use to access autostorage or other resources, you must explicitly assign a reference to this identity when configuring the Batch pool. This identity reference tells the Batch service which managed identity should be associated with the nodes for authentication purposes. This requirement is detailed in the Azure REST API documentation for Batch Account Update’s AutoStorageBaseProperties, specifically the nodeIdentityReference property. Therefore, you must configure your node identity reference in two interconnected places within the Azure portal interface to ensure correct functionality for autostorage access from the nodes.

You need to configure:

• The Node identity reference setting found within the batch account’s autostorage account configuration.
• The User assigned managed identity setting configured when creating or updating the batch pool.

It is important to understand the relationship between these two settings. You can define multiple user-assigned managed identities within the overall pool identity configuration. However, the specific managed identity designated in the Batch account’s Node identity reference for autostorage access must also be included in the list of user-assigned managed identities associated with the batch pool. If the identity specified in the node identity reference is not part of the pool’s assigned identities, nodes will fail to authenticate correctly.

Set Up the Autostorage Account’s Node Identity Reference¶

To configure the node identity reference within your Batch account’s autostorage settings, follow these steps. This step links a specific user-assigned managed identity to the autostorage account configuration, indicating which identity the nodes should use when accessing autostorage resources like application packages or task files. This configuration works in conjunction with the identity assigned to the pool itself.

1. In the Azure portal, search for and select Batch accounts.
2. In the list of batch accounts, select the name of your batch account.
3. In the navigation pane of the batch account, locate the Settings heading, and then select Storage account.
4. Under the STORAGE ACCOUNT INFORMATION section, confirm or select your autostorage account.
5. Scroll down or locate the Node identity reference heading, and then select Add.
6. Complete the process for adding your new user-assigned node identity reference by selecting the appropriate user-assigned managed identity from your subscription.

Set Up the Batch Pool’s User-Assigned Managed Identity¶

To configure the user-assigned managed identity for your batch pool, which assigns the identity to the virtual machines within the pool, follow these steps. This configuration is essential for allowing tasks running on the nodes to authenticate to Azure resources using the assigned identity. Remember that the identity specified in the Batch account’s Node identity reference must also be included here.

1. In the Azure portal, search for and select Batch accounts.
2. In the list of batch accounts, select the name of your batch account.
3. In the navigation pane of the batch account, locate the Features heading, and then select Pools.
4. On the batch pool page, select Add to create a new pool or select an existing pool to modify.
5. If adding a new pool, enter a Pool ID. In the Identity field, select User assigned. If modifying, navigate to the pool’s properties and find the Identity setting.
6. Locate the User assigned managed identity heading, and then select Add.
7. Complete the process for adding the user-assigned managed identity (or identities) to the batch pool. Ensure that the identity specified in the Batch account’s Node identity reference is included in this list.

Use Cases for Managed Identity in a Batch Node¶

Leveraging managed identity within a batch node enables secure access to various Azure services, significantly enhancing the security and manageability of your Batch workloads. Instead of baking credentials into task scripts or environment variables, tasks can request tokens for the managed identity assigned to the node. These tokens are then used to authenticate to supported Azure resources, adhering to the principle of least privilege.

Several common use cases demonstrate the value of configuring managed identity at the pool level. These include scenarios where nodes need to interact with external Azure services to perform their computational tasks.

Key use cases for managed identity in a batch node include:

• Download application packages from a batch pool’s autostorage.
• Download task resource files from a batch pool’s autostorage or other storage accounts.
• Access secrets from Azure Key Vault required by tasks.
• Interact with Azure Storage accounts (blobs, files, queues, tables) for input/output data.
• Connect to Azure Databases (SQL Database, Cosmos DB) securely.

Download Application Packages from a Batch Pool¶

When you define a batch pool, you have the option to specify application packages at the pool level. These packages, typically zip files containing your application executables and dependencies, are automatically downloaded from the Batch account’s autostorage account to every node in that pool upon node initialization. Using application packages simplifies deployment and ensures all nodes have the required software before running tasks. For more details on managing these packages, refer to the documentation on uploading and managing applications.

Before you can reference application packages when creating a batch pool, they must first be uploaded to your Batch account. Once uploaded, you can associate them with a pool during its creation or update process. To add application packages to your batch pool configuration, navigate to the Add pool page (or the pool’s properties) in the Azure portal, locate the OPTIONAL SETTINGS heading, and then select Application packages. Configuring this correctly, especially when using managed identities for autostorage access, ensures that nodes can successfully retrieve and install the necessary applications.

Behavior Scenarios for Application Package Download¶

The success of application package download on Batch nodes when using managed identities depends on the correct configuration of the managed identity in both the Batch account’s autostorage settings and the Batch pool’s identity configuration. Understanding these scenarios is crucial for troubleshooting download failures. The node’s operational status and the status of the application package download provide key indicators of configuration issues. You can monitor these statuses within the Azure portal on the overview page for each individual batch node.

To view node status and package download status in the Azure portal, navigate to the batch pool’s navigation pane under the General heading, select Nodes, and then select the name of the specific node you wish to inspect.

The following table outlines four distinct behavior scenarios that illustrate the interplay between managed identity usage, permissions, and pool configuration, and their impact on application package download within a batch pool:

Scenario Number	Managed Identity Usage	Managed Identity Permissions in Autostorage Account	Pool Creation Specification	Node Status	Package Download Status
1	Given in node identity reference	Sufficient permissions	Created in pool by using the same managed identity	Started successfully	Downloaded to the node in the root/applications directory
2	Given in node identity reference	Insufficient permissions	Created in pool by using the same managed identity	Started successfully, but in the Idle state	Not downloaded to the node
3	Not given in node identity reference	Sufficient or insufficient permissions	Created in pool by using the same or a different managed identity	Stuck indefinitely in the Starting state	Not downloaded to the node
4	Given in node identity reference	Sufficient or insufficient permissions	Created in pool by using a different managed identity	Unusable state	Not downloaded to the node

In Scenario 3, where the managed identity is not specified in the node identity reference within the Batch account’s autostorage settings, the Azure Batch service encounters an issue when trying to initialize the node. The node identity reference is effectively null or invalid from the perspective of accessing autostorage for pool-level resources. This prevents the node from progressing past the Starting state as it cannot complete the necessary setup steps, including downloading application packages. To diagnose this, you can upload Batch logs from the node’s overview page in the portal. Analyzing the agent-debug.log file from the uploaded logs will show repetitive messages indicating the node is stuck in the join process, such as “pool not fully joined yet, health=Status.TvmJoinPoolInProgress”.

In Scenario 4, if you define multiple managed identities when creating the batch pool but the specific managed identity referenced in the Batch account’s autostorage node identity reference is not included among the identities assigned to the pool itself, the Batch service cannot find a match. The node is assigned identities, but the one required by the autostorage configuration is not present or recognizable by the node agent attempting to access the autostorage. This mismatch leads to an error where the node becomes Unusable, and the portal will display a node error message similar to this:

Node has 1 error(s).

There was an error encountered on the node

Code: ApplicationPackageError

Message:
One or more application packages specified for the pool are invalid

This error, despite mentioning invalid packages, actually signifies a failure to authenticate and retrieve the packages due to the identity mismatch between the Batch account’s autostorage configuration and the identities assigned to the pool nodes.

Download Task Resource Files from a Batch Pool¶

When defining a task within an Azure Batch job, you can specify resource files that are required for the task to execute. These files, which can include input data, scripts, or configuration files, are automatically downloaded to the compute node from a specified source (often the autostorage account) before the task’s command line is run. This mechanism ensures that each task has access to the necessary data and files locally on the node. For more information on defining tasks and resource files, consult the Azure Batch documentation on Jobs and Tasks.

To specify task resource files within the Azure portal, follow these steps when adding or updating a task:

1. In the Azure portal, search for and select Batch accounts.
2. In the list of batch accounts, select the name of your batch account.
3. In the navigation pane of your batch account, locate the Features heading, and select Jobs.
4. On the Jobs page, select Add to create a new job, or select an existing job.
5. Fill out the required fields in the Add jobs pane (if creating a new job), and then select OK.
6. In the navigation pane of your batch job, locate the General heading, and then select Tasks.
7. On the Tasks page, select Add to create a new task, or select an existing task to modify.
8. In the Add Tasks pane, fill out any required fields for the task. Then, locate the ADVANCED SETTINGS heading, and select Resource files. Here you can define the source and destination for files needed by the task.

You can specify the resource files using different methods, each with implications for how managed identities are used. The available methods are described in the following table:

Method	Notes
Autostorage container	When using an Autostorage container, the identity reference setting for the resource file definition appears as None and cannot be modified within the task configuration. The node implicitly uses the identity defined in the Node identity reference for the autostorage account (which must also be on the pool) to access the autostorage account and retrieve resource files.
Container URL or HTTP URL	You can define a URL pointing to a container or a specific blob in another Azure Storage account, or even a publicly accessible HTTP URL. If using another Azure Storage account, sufficient permissions must be configured on that storage account for the managed identity used by the node, and that identity must be added to the batch pool.

Crucially, if your task requires access to the autostorage account to download resource files using the “Autostorage container” method, the managed identity must be correctly defined in both the Node identity reference setting within the Batch account’s autostorage configuration and included in the list of managed identities assigned to the Batch pool. Failure to configure both will result in the task failing to download the required files.

When specifying resource file definitions, the Blob prefix and File path parameters are optional but useful. The blob prefix allows you to filter for a specific subset of blobs within the source container. The file path is used to create a specified subfolder on the compute node where the downloaded blob files will be stored. If the file path is not defined, the files will be stored in the root directory of the task’s working directory (root/wd) on the node. The table below illustrates example resource file definitions using different methods.

Resource file type	Value	Blob prefix	File path	File mode (Linux only)	Identity reference
AutoStorageContainerName	<name-of-app>		mypath1		(None, implicitly uses Node Identity Reference)
StorageContainerUrl	https://<account-name>.blob.core.windows.net/con		mypath2		/subscriptions/<subscription-guid>/resourceGroups/<resource-group-name>/providers/Microsoft.ManagedIdentity/userAssignedIdentities/<user-assigned-identity-name> (Required if different from Pool Identity or if pool has multiple identities)
HttpUrl	https://<account-name>.blob.core.windows.net/con/api.crt		mypath3		/subscriptions/<subscription-guid>/resourceGroups/<resource-group-name>/providers/Microsoft.ManagedIdentity/userAssignedIdentities/<user-assigned-identity-name> (Required if different from Pool Identity or if pool has multiple identities)

Note that for StorageContainerUrl and HttpUrl, you can explicitly specify the identity reference if the pool has multiple user-assigned identities or if you need to use a specific one not implicitly covered by the autostorage configuration.

Behavior Scenarios for Task Resource File Download¶

Similar to application package downloads, the success of downloading task resource files from autostorage using managed identities configured on the Batch pool depends on the precise setup. Understanding how different configurations affect task execution and file retrieval is essential for diagnosing issues. The outcome of the task run, specifically whether the resource files are successfully downloaded, serves as a key indicator of configuration correctness.

The following table outlines four behavior scenarios that can occur when you use managed identity to create a batch pool and then create a task that requires retrieving a blob from an autostorage container using the “Autostorage container” method:

Scenario Number	Managed Identity Usage	Managed Identity Permissions in Autostorage Account	Pool Creation Specification	Result
1	Given in node identity reference	Sufficient permissions	Created in pool by using the same managed identity	Blob file is successfully downloaded to the node in the root/wd/<file-path> directory, as shown in the task overview page. Task proceeds as expected.
2	Given in node identity reference	Insufficient permissions	Created in pool by using the same managed identity	Task fails during the resource file download stage because of a ResourceContainerAccessDenied error. The error message will typically indicate “Access for one of the specified Azure Blob container(s) is denied”.
3	Not given in node identity reference	Sufficient or insufficient permissions	Created in pool by using the same or a different managed identity	Task fails during the resource file download stage because of a ResourceContainerAccessDenied error. The error message is the same: “Access for one of the specified Azure Blob container(s) is denied”.
4	Given in node identity reference	Sufficient or insufficient permissions	Created in pool by using a different managed identity	Task fails during the resource file listing/download stage because of a ResourceContainerListMiscError error. The error message is “Miscellaneous error encountered while listing one of the specified Azure Blob container(s)”.

In scenarios where the blob retrieval task fails, detailed error information can be found within the task properties in the Azure portal. Navigate to the Tasks page of the Batch job, select the name of the task that shows an error status, and then in the task page’s navigation pane, locate the General heading, select Properties, and then select Json View. The JSON display of properties will include the specific error message and code, along with other details about the failed task execution. For instance, in Scenario 4, the ResourceContainerListMiscError typically corresponds to an underlying “HTTP 400 Bad Request” error, indicating that the managed identity specified in the Batch account’s node identity reference could not be matched or used because it was not included in the set of managed identities assigned to the Batch pool itself. This confirms the requirement for the identity to be present in both configurations.

Verify That Your Managed Identity Can Access Azure Resources¶

To confirm that a managed identity assigned to an Azure Batch node possesses the necessary permissions to access other Azure resources, such as a storage account, you can perform a verification test directly from within a compute node. This procedure emulates the process a task would use to obtain a token for the managed identity and attempt to access the target resource. It’s a crucial step for diagnosing permission issues from the node’s perspective. Before performing this test, ensure the managed identity you are testing is correctly assigned to the Batch pool and, if applicable, referenced in the Batch account’s node identity reference settings.

This procedure specifically verifies the final steps of the authentication flow, assuming the identity is correctly assigned to the node. If the identity is not defined in the node identity reference (for autostorage access) or not assigned to the pool, the node won’t even be able to request a token for that identity via IMDS, blocking the process earlier.

To verify in a Windows node that a managed identity can access Azure resources, follow these steps:

1. Use Remote Desktop Protocol (RDP) to connect to one of the Batch nodes where you want to test the identity. Ensure RDP access is configured for the pool (e.g., via a NAT pool or public IP).

2. Once connected, open Postman or a similar tool capable of making HTTP requests. Send a GET request containing the Metadata: true header to the following URL. This request targets the Azure Instance Metadata Service (IMDS) endpoint available on Azure VMs to request a token for a managed identity:

   http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https://storage.azure.com/&mi_res_id=/subscriptions/<subscription-guid>/resourceGroups/<resource-group-name>/providers/Microsoft.ManagedIdentity/userAssignedIdentities/<user-assigned-identity-name>
   

   The IP address 169.254.169.254 is the well-known endpoint for the Azure Instance Metadata Service (IMDS). IMDS provides information about the VM instance itself and is used to request OAuth2 tokens for managed identities assigned to the VM.

   The mi_res_id parameter value in the URL, shown in bold in the example, is critical for user-assigned managed identities. It specifies the full Azure resource ID of the user-assigned managed identity for which you are requesting a token. To find this resource ID, along with the identity’s client ID and principal ID, follow these steps:
   a. In the Azure portal, search for and select Batch accounts.
   b. In the list of batch accounts, select the name of your batch account.
   c. In the navigation pane of the batch account, locate the Features heading, and then select Pools.
   d. In the list of batch pools, select the name of your batch pool.
   e. In the navigation pane of the batch pool, locate the General heading, and then select Properties.
   f. On the pool properties page, select Json view.
   g. In the JSON text, locate the identity/userAssignedIdentities list. Find the entry for the specific user-assigned managed identity you are testing and copy the values for its resourceId, clientId (a GUID), and principalId (a GUID). Use the resourceId value for the mi_res_id parameter in your IMDS request URL.

   After sending the GET request in Postman, the Body of the JSON response should contain an access_token (a long Base64 encoded string, the bearer token) and a client_id (a GUID). The client_id value in the response should match the clientId you copied from the pool properties, confirming you got a token for the correct identity.

   Warning: If your Batch pool has multiple user-assigned managed identities configured, and you do not specify the mi_res_id parameter in the IMDS request URL, IMDS will not know which identity token to return. In this scenario, Postman or your client will display a 400 Bad Request status, indicating ambiguity. Always specify mi_res_id when testing user-assigned identities if the pool has more than one.

3. Copy the full access_token (the bearer token) from the IMDS response. Now, use this token to attempt an authenticated request to the target Azure resource, such as listing blobs in your autostorage account container. In Postman, make another request (e.g., a GET request to list blobs in a container using the Storage Service REST API). Add an Authorization header with the value Bearer <your-access-token>. Also, include the required x-ms-version header for Azure Storage API requests (e.g., 2020-04-08). If the managed identity lacks sufficient permissions on the storage account, the storage service will respond with an HTTP 403 Forbidden error. The error response body will likely contain an “AuthorizationPermissionMismatch” error code or similar, with a message like “This request is not authorized to perform this operation using this permission.”

   Note: The x-ms-version header is mandatory for most Azure Storage REST API operations. Refer to the Azure Storage documentation (like the Get Blob API reference) for the appropriate version and request format.

   Conversely, if the request succeeds (e.g., returns HTTP 200 OK and a list of blobs), it confirms that the managed identity assigned to the node has sufficient permissions on that specific storage resource for the requested operation. This end-to-end test provides definitive proof of the identity’s access capabilities from the node.

Using managed identities with Azure Batch significantly improves the security posture compared to managing secrets manually. By understanding the different levels of identity assignment (account vs. pool) and their interaction with services like autostorage, you can configure your Batch environment for secure and efficient operation. Properly diagnosing issues often involves verifying both the identity assignment and the corresponding RBAC permissions.

Do you have questions about configuring managed identities for your specific Azure Batch scenario? Share your thoughts or challenges in the comments below!