Managed Identities for Azure resources provide an automatic way to authenticate Azure services without storing credentials in your code. This feature eliminates the need to manage secrets, connection strings, or certificates manually, significantly improving security posture.
There are two types o…Managed Identities for Azure resources provide an automatic way to authenticate Azure services without storing credentials in your code. This feature eliminates the need to manage secrets, connection strings, or certificates manually, significantly improving security posture.
There are two types of managed identities:
1. **System-assigned managed identity**: Created and tied to a specific Azure resource (like a Virtual Machine or App Service). When you enable it, Azure creates an identity in the Azure AD tenant. The identity lifecycle is tied to the resource - when the resource is deleted, the identity is automatically removed.
2. **User-assigned managed identity**: Created as a standalone Azure resource that can be assigned to one or more Azure services. The identity exists independently of the resources using it, giving you more flexibility in managing the lifecycle.
**Implementation Steps:**
1. Enable managed identity on your Azure resource through the Azure Portal, CLI, PowerShell, or ARM templates
2. Grant the identity appropriate permissions using Azure RBAC to access target resources
3. Update your application code to use the Azure Identity client library
**Code Example:**
csharp
var credential = new DefaultAzureCredential();
var blobServiceClient = new BlobServiceClient(
new Uri("https://mystorageaccount.blob.core.windows.net"),
credential);
The DefaultAzureCredential automatically detects the managed identity when running in Azure and retrieves tokens for authentication.
**Key Benefits:**
- No credential management required in application code
- Automatic token rotation handled by Azure AD
- Reduced risk of credential exposure or leakage
- Simplified authentication to Azure services supporting Azure AD authentication
**Supported Services:**
Most Azure services support managed identities, including Azure Key Vault, Azure Storage, Azure SQL Database, Azure Service Bus, and many others. This enables secure, seamless authentication between Azure resources in your solutions.
Implement Managed Identities for Azure Resources
Why Managed Identities Matter
Managed identities solve one of the most critical security challenges in cloud computing: credential management. Traditionally, applications needed to store connection strings, passwords, or API keys to access Azure services. This created security risks including credential exposure, rotation complexity, and potential breaches. Managed identities eliminate these concerns by allowing Azure resources to authenticate to supported services using Azure Active Directory (Azure AD) tokens, with no credentials stored in code or configuration files.
What Are Managed Identities?
Managed identities are a feature of Azure Active Directory that provides Azure services with an automatically managed identity. This identity can be used to authenticate to any service that supports Azure AD authentication. There are two types of managed identities:
1. System-assigned Managed Identity - Created as part of an Azure resource (e.g., Azure VM, App Service, Azure Functions) - Lifecycle is tied to the resource; deleted when the resource is deleted - Cannot be shared across multiple resources - Each resource gets its own unique identity
2. User-assigned Managed Identity - Created as a standalone Azure resource - Has an independent lifecycle from the resources it's assigned to - Can be shared across multiple Azure resources - Useful when multiple resources need the same permissions
How Managed Identities Work
The authentication flow follows these steps:
1. Identity Creation: When you enable a managed identity, Azure creates a service principal in Azure AD for that identity.
2. Role Assignment: You grant the identity access to Azure resources using Azure Role-Based Access Control (RBAC).
3. Token Request: Your application code requests an access token from the Azure Instance Metadata Service (IMDS) endpoint at http://169.254.169.254/metadata/identity/oauth2/token.
4. Token Retrieval: Azure AD returns an access token to your application.
5. Resource Access: Your application uses the token to authenticate to Azure services like Key Vault, Storage, SQL Database, etc.
Code Example Using Azure SDK
Using the Azure.Identity library in C#: var credential = new DefaultAzureCredential(); var client = new SecretClient(new Uri("https://myvault.vault.azure.net/"), credential);
The DefaultAzureCredential automatically uses the managed identity when running in Azure.
Services That Support Managed Identities
- Azure Virtual Machines - Azure App Service and Azure Functions - Azure Kubernetes Service (AKS) - Azure Logic Apps - Azure Data Factory - Azure API Management - Azure Container Instances - And many more...
Exam Tips: Answering Questions on Managed Identities
Key Concepts to Remember:
1. System-assigned vs User-assigned: Know the differences. System-assigned is tied to one resource; user-assigned can be shared and exists independently.
2. IMDS Endpoint: Remember the endpoint 169.254.169.254 is used to obtain tokens. This is a link-local address accessible only from within the Azure resource.
3. DefaultAzureCredential: This is the recommended approach in the Azure SDK as it tries multiple authentication methods including managed identity, environment variables, and Azure CLI.
4. RBAC Requirements: Managed identities still require proper role assignments. Creating an identity alone does not grant access to resources.
5. Supported Services: Not all Azure services support managed identities. Know which services can use managed identities (sources) and which services accept Azure AD authentication (targets).
Common Exam Scenarios:
- Scenario: An App Service needs to access Key Vault secrets. Answer: Enable system-assigned managed identity on App Service, grant Key Vault access policy to the identity.
- Scenario: Multiple VMs need identical access to a Storage Account. Answer: Create a user-assigned managed identity, assign it to all VMs, grant Storage Blob Data Reader role.
- Scenario: Eliminate hard-coded credentials in application code. Answer: Use managed identity with DefaultAzureCredential or ManagedIdentityCredential class.
Watch Out For:
- Questions asking about credential rotation - managed identities handle this automatically - Scenarios requiring identity sharing across resources point to user-assigned identities - Questions about local development - managed identities only work in Azure; use DefaultAzureCredential for flexibility - Token caching - tokens are cached and refreshed automatically by the Azure SDK