Exploring Managed Identity in Azure DevOps

Exploring Managed Identity in Azure DevOps

Managed Identity is a feature provided by Azure Active Directory (now Microsoft Entra ID) that simplifies identity management for Azure resources. By integrating Managed Identity with Azure DevOps, you can securely authenticate and access Azure resources from pipelines and other DevOps processes without managing secrets or credentials manually.

Types of Managed Identity

1. System-Assigned Managed Identity:

   • Automatically created and managed by Azure.

   • Tied to an individual Azure resource (e.g., Virtual Machine, App Service, Azure Kubernetes Service).

   • Deleted automatically when the resource is deleted.

2. User-Assigned Managed Identity:

   • Created as a standalone Azure resource.

   • Can be assigned to multiple Azure resources.

   • Requires explicit deletion when no longer needed.

Use Cases of Managed Identity in Azure DevOps

1. Accessing Azure Resources in Pipelines: Authenticate Azure DevOps pipelines to Azure services (e.g., Key Vault, Storage, Resource Manager).

2. Eliminating Secrets in Pipelines: Use Managed Identity instead of Service Principals with client secrets.

3. Secure Access to Key Vault: Retrieve secrets or certificates in a pipeline securely without storing credentials in pipeline configurations.

4. Role-Based Access Control (RBAC): Assign specific roles to the Managed Identity to control access to Azure resources.

How Managed Identity Works with Azure DevOps

Azure DevOps itself does not directly support Managed Identity. However, when using Azure-hosted agents (e.g., Virtual Machines or App Services with System-Assigned or User-Assigned Managed Identity), you can leverage Managed Identity to authenticate Azure CLI or SDK commands in your pipeline.

Implementation Steps

1. Enable Managed Identity on Azure Resource

   • For a System-Assigned Managed Identity:

     • Navigate to the Azure resource (e.g., VM, App Service).

     • Go to Identity under the resource settings.

     • Enable System-Assigned Managed Identity.

     • Azure will automatically register the resource in Microsoft Entra ID.

   • For a User-Assigned Managed Identity:

     • Navigate to Microsoft Entra ID →** Managed Identities**.

     • Create a new User-Assigned Managed Identity.

     • Assign it to the relevant Azure resources.

2. Assign Roles to the Managed Identity

   • Navigate to the Azure resource that your pipeline needs to access.

   • Go to Access Control (IAM) →** Add Role Assignment**.

   • Assign a suitable role (e.g., Reader, Contributor) to the Managed Identity.

3. Use Managed Identity in Azure DevOps Pipeline

   • Deploy Azure resources using an Azure-hosted agent (e.g., VM or App Service) that has a Managed Identity enabled.

   • Use Azure CLI, PowerShell, or REST API commands in your pipeline to authenticate and interact with Azure resources.

   • Example YAML Pipeline:

   xxxxxxxxxx
   12
   1
   trigger:
   2
   - main
   3
   pool:
   4
   vmImage: 'ubuntu-latest'
   5
   steps:
   6
   - task: AzureCLI@2
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   inputs:
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      scriptType: 'bash'
   9
      scriptLocation: 'inlineScript'
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      inlineScript: |
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         az login --identity
   12
         az keyvault secret show --vault-name "<KeyVaultName>" --name "<SecretName>"
   

4. Configure Pipeline to Run on Azure-Hosted Agent Ensure the agent pool you select in the pipeline YAML uses Azure resources with Managed Identity enabled.

Benefits of Using Managed Identity in Azure DevOps

1. Enhanced Security:

   • No need to manage credentials like client secrets or keys.

   • Authentication is handled by Azure directly.

2. Seamless Integration: Works seamlessly with Azure CLI, SDKs, and REST APIs in pipelines.

3. Simplified Credential Management: Eliminates manual credential rotation and storage.

4. Scalability: User-Assigned Managed Identities can be shared across multiple Azure resources and scaled easily.

Limitations of Managed Identity with Azure DevOps

1. Not Directly Supported: Managed Identity is not natively integrated into Azure DevOps. It requires using Azure-hosted agents with Managed Identity-enabled resources.

2. Dependency on Azure Resources: Pipelines must run on resources with Managed Identity enabled, such as VMs or App Services.

3. Complex Configuration for Some Use Cases: Additional setup may be required for resources that are not natively compatible with Managed Identity.

Best Practices for Managed Identity in Azure DevOps

1. Use System-Assigned Managed Identity for Single Resources: When the Managed Identity is tied to a single resource (e.g., VM running pipelines).

2. Leverage User-Assigned Managed Identity for Reusability: When multiple resources need to share a single identity.

3. Assign Least Privilege Roles: Grant only the necessary permissions to the Managed Identity to access resources.

4. Monitor and Audit Access: Use Azure Monitor and Microsoft Entra logs to track the usage of Managed Identity.

5. Combine with Key Vault: Use Managed Identity to access secrets from Azure Key Vault securely in pipelines.

Summary

By using Managed Identity in Azure DevOps, you can significantly enhance the security and simplicity of accessing Azure resources, making it a powerful tool for DevOps automation and resource management.