What is service principal, in the context of azure AKS?

In the context of Azure AKS (Azure Kubernetes Service), a service principal is an identity created for use with applications, services, and automation tools to access resources within an Azure AD (Active Directory) or Azure subscription. Service principals are typically used to enable secure and programmatic access to Azure resources.

When you deploy an AKS cluster, you often need to integrate it with other Azure services or grant permissions to access resources. To achieve this, you can use a service principal to authenticate and authorize access.

Here’s how it generally works:

1. Service Principal Creation: You create a service principal in Azure AD. This involves defining a new application, which gets assigned a unique identifier (Application ID) and an authentication key (Client Secret or Certificate). This information is used by the application or service to authenticate with Azure AD.
2. Role Assignment: Once the service principal is created, you can assign it specific roles and permissions within Azure, specifying what resources it can access and what actions it can perform. For AKS, you might assign roles like Contributor or AKS Cluster Admin to allow the service principal to manage the AKS cluster.
3. Integration with AKS: The service principal’s credentials (Application ID and Client Secret or Certificate) are then used to configure AKS to authenticate and interact with Azure resources. This could include things like pulling container images from Azure Container Registry, accessing storage accounts, or managing other resources associated with the AKS cluster.

Using a service principal is considered a best practice for security reasons. It allows you to control and restrict permissions more granularly, and you can easily rotate credentials when needed without affecting the service itself.

In summary, a service principal in the context of Azure AKS is an identity that enables secure access to Azure resources, allowing applications and services to interact with and manage the AKS cluster and associated resources in a controlled and secure manner.

How can I check if our service principal is expired or not?

To check if a service principal’s credentials (such as a client secret) have expired, you typically need to refer to the expiration policies of the specific credential associated with the service principal. Here are steps you can take to check the expiration status:

1. Using Azure Portal, Azure Active Directory:
   • Navigate to the Azure portal.
   • Go to “Azure Active Directory” > “App registrations” > “Your application” (the service principal).
   • Under “Certificates & secrets” or “Authentication,” you can find the details of your credentials, including their expiration dates.
2. Azure CLI:
   • You can use the Azure CLI to check the expiration of a service principal’s credentials.

az ad app show --id <application-id>