Applying Security Patching to AKS Clusters Automatically

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Pulumi · Accepted Answer

Applying security patches automatically to Azure Kubernetes Service (AKS) clusters is a critical aspect of maintaining the security and reliability of your applications. In AKS, you can configure your cluster to automatically upgrade to the latest patch versions of Kubernetes through AKS itself or through maintenance configurations.

Pulumi provides resources for managing AKS clusters, including setting up auto-upgrade configurations. The resource `azure.containerservice.KubernetesCluster` is used for creating and managing an AKS cluster.

Below is a Pulumi program in TypeScript that defines an AKS cluster with an auto-upgrade profile which allows the cluster to automatically apply security patches.

```typescript
import * as azure from "@pulumi/azure";

// Define the AKS cluster with an auto-upgrade profile.
const aksCluster = new azure.containerservice.KubernetesCluster("aksCluster", {
    // Required resource fields like location, resource group name, and DNS prefix need to be defined.
    // Replace these placeholder values with your specific information.
    location: "East US",
    resourceGroupName: "myResourceGroup",
    dnsPrefix: "myakscluster",
    
    // The default node pool of the cluster.
    defaultNodePool: {
        name: "default",
        nodeCount: 3,
        vmSize: "Standard_DS2_v2",
    },
    
    // Auto-upgrade profile for the cluster.
    autoScalerProfile: {
        // There are multiple settings you could configure here.
        // For instance, you could set a particular K8s version to upgrade to, specific times for maintenance, etc.
        // As an example, `kubernetesVersion` specifies the desired version of Kubernetes to use.
        // Using "latest" would mean AKS uses the latest available patch release.
        kubernetesVersion: "latest",
    },

// Identity settings, defining the type of identity used for the AKS cluster.
    identity: {
        type: "SystemAssigned",
    },
    
    // Enabling Role-Based Access Control (RBAC) is a recommended best practice.
    roleBasedAccessControl: {
        enabled: true,
    },

// Monitoring and logging are also important for maintaining the health and security of the cluster.
    addonProfile: {
        omsAgent: {
            enabled: true,
            logAnalyticsWorkspaceId: "workspaceId", // replace with your Log Analytics Workspace ID.
        },
    },

// ... other configurations
});

// To keep things simple, we're only defining required and minimal spec for the AKS cluster.
// A production-grade cluster would include more settings around networking, security, monitoring, etc.

// Export the Kubeconfig of the AKS cluster
export const kubeconfig = aksCluster.kubeConfigRaw;
```

This Pulumi program defines a AKS cluster resource named `aksCluster`. The profile describes the upgrade settings for the cluster:

- `kubernetesVersion`: Here, `"latest"` is used as an example to signal AKS to use the latest stable version of Kubernetes, ensuring that we are up to date with the latest patches.
- `location`: The Azure region where you want to deploy your cluster.
- `resourceGroupName`: The existing Azure Resource Group in which the AKS cluster will reside.
- `dnsPrefix`: A unique DNS prefix that is used for the AKS cluster's API server URL.
- `defaultNodePool`: Describes the default node pool for the cluster, including the VM size and the count.
- `identity`: Specifies the identity used for the cluster, which in this case is system-assigned managed identity.
- `roleBasedAccessControl`: Whether RBAC is enabled on the cluster.
- `addonProfile`: An example add-on for Azure Monitor for containers, which requires a Log Analytics workspace.

After this program is applied using Pulumi, the AKS cluster will be provisioned with the configurations specified. When a new Kubernetes patch version becomes available, AKS will automatically apply the update according to the auto-upgrade profile.

You can apply this Pulumi program by running the following commands:
- `pulumi up` to preview and deploy the changes.
- `pulumi stack output kubeconfig` to get the generated kubeconfig for your cluster after deployment.

Make sure to replace the placeholders such as `resourceGroupName`, `workspaceId`, and other settings with your own specific values.

Please note that the auto-upgrade feature might have specific version compatibility and requirements. It is vital to consult the Azure AKS documentation and Pulumi resource documentation for `azure.containerservice.KubernetesCluster` to understand the available properties and their usage fully.

Refer to the Pulumi documentation for [`azure.containerservice.KubernetesCluster`](https://www.pulumi.com/registry/packages/azure/api-docs/containerservice/kubernetescluster/) for more details on the resource options and how to further customize your AKS cluster.