Leveraging Managed Identities in Azure

In the world of cloud computing, especially within Microsoft Azure, security and seamless access management are paramount. One of the most powerful and elegant solutions for managing credentials for Azure services is Azure Active Directory (Azure AD) Managed Identities. This feature eliminates the need for developers to manage sensitive credentials like connection strings or API keys, significantly reducing the risk of exposure and simplifying application development.

What are Managed Identities?

Managed Identities provide an Azure AD identity for Azure resources. When enabled, Azure automatically creates and manages this identity. You can then use this identity to authenticate to any service that supports Azure AD authentication, without needing to manage any credentials in your code or configuration files.

There are two types of managed identities:

• System-assigned managed identity: This identity is directly tied to an Azure resource. When you enable it, a new identity is created in Azure AD. This identity is deleted when the resource is deleted.
• User-assigned managed identity: This identity can be created as a standalone Azure resource and then assigned to one or more Azure resources. This allows you to reuse the same identity across multiple resources.

Conceptual diagram of Azure Managed Identities

Why Use Managed Identities?

The benefits of using managed identities are substantial:

• Enhanced Security: No need to store or manage secrets (like passwords, connection strings, or keys) in your code, configuration files, or Azure Key Vault. Azure handles the credential rotation and lifecycle.
• Simplified Development: Developers can focus on building application logic rather than managing authentication infrastructure.
• Improved Compliance: Reduces the attack surface and helps meet compliance requirements by eliminating manual secret management.
• Granular Access Control: You can grant the managed identity specific permissions to other Azure resources, adhering to the principle of least privilege.

Common Use Cases

Managed identities are ideal for scenarios where an Azure resource needs to access other Azure services. Some common examples include:

• An Azure Web App accessing Azure SQL Database.
• An Azure Function reading secrets from Azure Key Vault.
• A Virtual Machine connecting to Azure Storage.
• Azure Kubernetes Service (AKS) pods interacting with Azure Cosmos DB.

How to Implement Managed Identities

Implementing managed identities typically involves a few key steps:

1. Enable Managed Identity on the Azure Resource

This is done within the Azure portal, Azure CLI, PowerShell, or ARM/Bicep templates. For example, using Azure CLI to enable a system-assigned managed identity on a Virtual Machine:

az vm identity assign --resource-group MyResourceGroup --name MyVM

2. Grant Permissions to the Managed Identity

Once the identity is created, you need to grant it permissions to access the target resource. This is done using Azure Role-Based Access Control (RBAC).

For example, granting read access to a Storage Account:

az role assignment create --assignee  --role "Storage Blob Data Reader" --scope "/subscriptions/YOUR_SUBSCRIPTION_ID/resourceGroups/MyResourceGroup/providers/Microsoft.Storage/storageAccounts/MyStorageAccount"

You can retrieve the client ID of the managed identity from its properties in Azure AD.

3. Authenticate Using the Managed Identity in Your Application

Azure SDKs provide built-in support for managed identities. When your application runs on an Azure resource with a managed identity enabled, the SDK can automatically acquire tokens without any explicit credential configuration.

Here's a conceptual example using the Azure SDK for .NET to connect to Azure Key Vault:

// Using Azure.Identity and Azure.Security.KeyVault.Secrets
            using Azure.Identity;
            using Azure.Security.KeyVault.Secrets;

            // ...

            string keyVaultName = "my-keyvault";
            var kvUri = $"https://{keyVaultName}.vault.azure.net";

            // DefaultAzureCredential will automatically try to use Managed Identity
            // when running on an Azure resource.
            var client = new SecretClient(new Uri(kvUri), new DefaultAzureCredential());

            KeyVaultSecret secret = client.GetSecret("my-secret-name");
            Console.WriteLine($"Secret value: {secret.Value}");
            

The DefaultAzureCredential class is a powerful tool that chains multiple credential types, including managed identities, making authentication seamless across different environments.

Conclusion

Managed identities are a cornerstone of secure and efficient cloud application development on Azure. By abstracting credential management, they allow developers to build more robust applications faster, with a significantly reduced security risk. Embracing managed identities is a best practice that every Azure developer should adopt.

Ready to secure your Azure applications? Start implementing Managed Identities today!