Azure Managed Identity Token: A Comprehensive Guide

Azure Managed Identity Token is a game-changer for Azure users. It allows Azure resources to authenticate to Azure services without the need for credentials.

With Azure Managed Identity, you don't need to store or manage credentials, reducing the risk of security breaches. This is especially useful for Azure virtual machines, where credentials can often be compromised.

Azure Managed Identity Token is a JSON Web Token (JWT) that contains information about the Azure resource and its identity. It's used to authenticate the resource to Azure services, such as Azure Key Vault and Azure Storage.

Azure Managed Identity Token is a type of token that allows Azure services to authenticate to other services without needing to store credentials.

It's a unique token that's tied to the Azure resource, and it's used to authenticate to Azure services like Azure Storage and Azure Key Vault.

This token is automatically managed by Azure, hence the name "Managed Identity".

It's not a password or a secret key, but rather a token that's used to prove the identity of the Azure resource.

The token is valid for a short period of time, typically 1-2 hours, and can be renewed automatically by Azure.

Azure Managed Identity Token is used to authenticate to services that support Azure Active Directory (AAD) authentication.

It's a more secure way to authenticate, as it eliminates the need to store credentials in code or configuration files.

To get a token, you can use HTTP or the Azure identity client library. Using HTTP is a straightforward way to acquire an access token, making it accessible to any client application running on the VM that can make HTTP REST calls.

The fundamental interface for acquiring an access token using HTTP is based on REST, and it's similar to the Microsoft Entra programming model. The client uses an endpoint on the virtual machine (vs a Microsoft Entra endpoint).

To make a GET request, you'll need to use the Azure Instance Metadata Service (IMDS) endpoint, which is recommended. The endpoint is http://169.254.169.254/metadata/identity/oauth2/token.

The required query string parameters are api-version and resource. You'll also need to include the Metadata HTTP request header field, which must be set to "true" in all lower case.

Optional query string parameters include object_id, client_id, and msi_res_id, which are required if your VM has multiple user-assigned managed identities.

Here's a summary of the required and optional query string parameters:

You can also use the Azure identity client library, which is the recommended way to use managed identities. This approach makes it easy to use managed identities with Azure SDKs.

Token Management is a crucial aspect of Azure Managed Identity Token. The token is valid for a limited time, specifically 60 minutes, after which it expires. This is why it's essential to implement token caching in your code.

To get a token, you can use the Azure Instance Metadata Service (IMDS) endpoint, which is the recommended approach. This involves making an HTTP GET request to the endpoint, including the necessary parameters such as api-version, resource, and Metadata.

Here's a breakdown of the IMDS endpoint parameters:

Using the Azure identity client library is also a recommended way to use managed identities. This approach makes it easy to use Managed Identities with Azure SDKs. You can directly use the Azure SDK clients without worrying about getting tokens.

The managed identities subsystem caches tokens, but it's still essential to implement token caching in your code. This is because a cache miss can occur due to no token in the managed identities for Azure resources subsystem cache, or the cached token can be expired.

Azure managed identity token is a powerful tool for authentication, and understanding the different types of identities is crucial for its utilization. There are two main types of managed identities: system-assigned and user-assigned.

System-assigned managed identities are created as part of an Azure resource, such as a virtual machine or app service, and are tied to the life cycle of that resource. This means they are automatically deleted when the resource is deleted.

User-assigned managed identities, on the other hand, are created as standalone Azure resources and have an independent life cycle. This means they must be explicitly deleted when no longer needed.

Here's a comparison of the two types of managed identities:

Understanding these differences will help you choose the right type of managed identity for your Azure resources and ensure secure and efficient authentication.

There are two types of managed identities: system-assigned and user-assigned. System-assigned managed identities are created as part of an Azure resource, such as a virtual machine or app service.

These identities are shared with the life cycle of the Azure resource they are created with, meaning they are deleted when the resource is deleted. They can't be shared across multiple Azure resources and are best suited for workloads contained within a single resource.

User-assigned managed identities, on the other hand, are created as standalone Azure resources. They have an independent life cycle and must be explicitly deleted. This type of identity can be shared across multiple Azure resources, making it ideal for workloads that run on multiple resources and need to access the same secure resource.

Here's a comparison of the two types of managed identities:

To effectively utilize resources, it's essential to understand how managed identities work in Azure. You can use managed identities by creating one in Azure, choosing between system-assigned or user-assigned managed identity.

To create a managed identity, you can choose between system-assigned or user-assigned managed identity. System-assigned managed identity is automatically created and managed by Azure, while user-assigned managed identity requires manual creation and management.

To use a managed identity, you'll need to authorize it to access the target service. This involves granting the necessary permissions to the managed identity. Once authorized, you can use the managed identity to access a resource using the Azure SDK with the Azure.Identity library.

To access a resource, you can use the managed identity as a feature of the source resource. Some resources offer connectors that know how to use managed identities for connections. This simplifies the process and makes it easier to manage identities.

Here are the steps to use managed identities in Azure:

Azure managed identity tokens support authentication to services that support Microsoft Entra authentication, which is a key feature of managed identities for Azure resources.

To use managed identities for Azure resources, you'll need to choose an Azure service that supports Microsoft Entra authentication.

Azure services that support managed identities for Azure resources include services that can use Microsoft Entra authentication, such as Azure resources that support managed identities.

These services can use managed identities for Azure resources to authenticate, making it easier to manage access to Azure resources.

For a full list of supported Azure services, you can refer to the services that support managed identities for Azure resources.

To implement Azure managed identities, you'll need to follow seven specific steps. These steps ensure a seamless integration of managed identities with your Azure resources.

First, you need to request Azure Resource Manager to enable or create a managed identity. This can be a system-assigned managed identity or a user-assigned managed identity.

To enable a system-assigned managed identity, Azure Resource Manager creates a service principal for the managed identity within Active Directory. The trusted Azure AD tenant hosts the new service principal.

The application code running on the VM requests a token from the IMDS endpoint, accessible only from within the virtual machine. Certain parameters are sent for token requests, including the client ID and certificate.

Here are the 7 steps to implement Azure managed identities:

To implement Azure managed identities, you'll need to follow these seven steps. Here's a concise overview of what to expect:

Step 1: Request is submitted for Azure Resource Manager to enable (in case of a system-assigned managed identity) or create (in case of a user-assigned managed identity) a managed identity.

To get started, you'll need to request a managed identity from Azure Resource Manager. This can be done for system-assigned managed identities, which are enabled on the VM, or user-assigned managed identities, which are created separately.

Step 2: In the case of the system-assigned managed identity, when the Azure Resource Manager receives a request to enable a managed identity on the VM, it creates a service principal for the managed identity within AD. The trusted Azure AD tenant will host the new service principal.

System-assigned managed identities are automatically created by Azure Resource Manager when you enable them on a VM.

Step 3: For system-assigned managed identities, the resource manager updates the virtual machine identity using the Azure Instance Metadata Service (IMDS) identity endpoint. This configuration provides the endpoint with the service principal client ID and certificate.

This step is specific to system-assigned managed identities and involves updating the VM's identity using the IMDS identity endpoint.

Step 4: After you create the service principal and enable or assign the virtual machine identity, you need to use the service principal information to assign an appropriate RBAC to the Azure resource.

Once the service principal is created and the VM identity is updated, you'll need to assign the necessary RBAC permissions to the Azure resource.

Step 5: The application code running on the VM requests a token from the IMDS endpoint, accessible only from within the virtual machine. Certain parameters are sent for token requests.

The application code running on the VM will request a token from the IMDS endpoint, which will be used to authenticate with Azure AD.

Step 6: Access token request is sent to Azure AD using the client ID and certificate. Azure AD returns a JSON Web Token (JWT) access token.

The IMDS endpoint will use the client ID and certificate to request an access token from Azure AD, which will be returned as a JSON Web Token.

Step 7: The code now sends the Azure AD token to access the desired Azure service, so long as it supports Azure AD authentication.

With the access token in hand, the application code can now authenticate with the desired Azure service that supports Azure AD authentication.

Managed identities offer several advantages when it comes to authentication and security.

First and foremost, managed identities eliminate the need to store credentials within application code, which can be a major security risk. This is because credentials can be leaked, either intentionally or unintentionally, and managed identities prevent this from happening.

Managed identities are also incredibly versatile, allowing you to authenticate any Azure resources that support AD authentication. All you need to do is assign the correct role to the identity on the required resource using IAM.

One of the best things about managed identities is that they don't come with any additional charges. This makes them a cost-effective solution for authentication and security.

Here are the three benefits of using managed identities in a concise list:

System-Assigned and User-Assigned Managed Identities are two types of managed identities used in Azure.

System-assigned managed identities are created as part of Azure resource development and have a lifecycle dependent on the resource they're created with. They are removed as the resource is deleted.

User-assigned managed identities, on the other hand, are created as standalone resources and can be attached to multiple Azure service instances. Their lifecycle is depleted separately as they're independent Azure resources.

Here's a comparison of the two:

One important thing to remember is that a managed identity, whether system-assigned or user-assigned, is a special kind of service principal used only with Azure resources.

Deleting a managed identity in Azure can have some unexpected consequences. Tokens issued before the identity was deleted will still be valid until their original expiry.

Some target endpoints' authorization systems may carry out additional checks in the directory for the identity, causing requests to fail because the object can't be found.

Azure RBAC, however, will continue to accept requests from expired tokens.

Understanding the Security Boundary for Resources is crucial to ensure secure access to your Azure resources. This boundary determines what can and can't access your managed identities.

The security boundary of a managed identity is the resource to which it's attached. For example, if you have a virtual machine with managed identities enabled, the security boundary is the virtual machine itself.

This means that any code running on that VM can call the managed identities endpoint and request tokens. This is a key aspect to consider when working with managed identities for Azure resources.

To put it simply, the security boundary is the "container" that holds your managed identity, and it's essential to understand this concept to ensure secure access to your resources.

Here's a quick summary of the security boundary for different types of resources:

By understanding the security boundary, you can better manage access to your Azure resources and ensure that only authorized code can access your managed identities.

As you delete a managed identity, you should be aware of what happens to the tokens associated with it. Tokens that were issued before the identity was deleted will still be valid until their original expiry.

This means that even though the identity is deleted, the tokens that were previously issued will continue to work until they expire.

Some target endpoints' authorization systems may not accept requests from the deleted identity, as they may carry out other checks in the directory for the identity.

However, some systems like Azure RBAC will continue to accept requests from the token until it expires, ensuring a smooth transition.