Custom DNS Configuration for AI Development on Azure Kubernetes Service

Question

Pulumi · Accepted Answer

To create a custom DNS configuration for an AI development environment on Azure Kubernetes Service (AKS), you'll need to configure various components within Azure. At its core, an AKS cluster provides a managed Kubernetes service that simplifies the deployment and operations of a Kubernetes cluster in Azure. To customize the DNS configurations, you may need to set up specific network configurations during the creation of the AKS cluster or modify them post-deployment.

For setting up a custom DNS within an AKS cluster, Azure provides specific network and add-on profile configurations that can be leveraged. Here are the main steps, in Pulumi, for achieving a custom DNS configuration:

1. Define a virtual network and a subnet to host the AKS cluster, which gives you more control over the network configuration.
2. Create an AKS cluster in the specified virtual network.
3. Configure DNS service settings as part of the cluster's network profile. The `dns_service_ip` and `service_cidr` properties can be customized to fit the required DNS configuration.
4. Define an add-on profile for enabling Azure policies if required.

Here is a program written in Python using Pulumi to accomplish these steps:

```python
import pulumi
import pulumi_azure_native as azure_native
from pulumi_azure_native import resources, containerservice, network

# Provide your resource group and location
resource_group = resources.ResourceGroup('my-rg')

# Set up a virtual network and subnet specifically for the AKS cluster
vnet = network.VirtualNetwork(
    'my-aks-vnet',
    resource_group_name=resource_group.name,
    location=resource_group.location,
    address_space=network.AddressSpaceArgs(
        address_prefixes=["10.0.0.0/16"],
    )
)

subnet = network.Subnet(
    'my-aks-subnet',
    resource_group_name=resource_group.name,
    address_prefix="10.0.1.0/24",
    virtual_network_name=vnet.name,
)

# Create an AKS cluster with custom DNS settings within our virtual network
aks_cluster = containerservice.ManagedCluster(
    'my-aks-cluster',
    resource_group_name=resource_group.name,
    location=resource_group.location,
    dns_prefix="myaksdns",
    agent_pool_profiles=[{
        "count": 3,
        "max_pods": 110,
        "mode": "System",
        "name": "agentpool",
        "node_labels": {},
        "os_disk_size_gb": 30,
        "os_type": "Linux",
        "type": "VirtualMachineScaleSets",
        "vm_size": "Standard_DS2_v2",
        "vnet_subnet_id": subnet.id,
    }],
    network_profile=containerservice.ContainerServiceNetworkProfileArgs(
        dns_service_ip="10.0.2.10",
        service_cidr="10.0.2.0/24",
        network_plugin="azure",  # Use Azure CNI networking plugin
    ),
)

# Export the KubeConfig 
kube_config = pulumi.Output.secret(aks_cluster.kube_config_raw)
pulumi.export('kubeConfig', kube_config)
```

Explanation of the program:

- We import the Pulumi Azure Native package which allows us to interact with Azure resources.
- The `ResourceGroup` resource is created to organize all the resources associated with the AKS cluster.
- We define a virtual network and subnet using the `VirtualNetwork` and `Subnet` resources, which allows us to customize the network configuration including IP ranges.
- The AKS cluster is created with the `ManagedCluster` resource. We provide it a DNS prefix and configure the agent pool to specify the number of nodes and other settings.
- The `network_profile` argument is crucial here as it lets us set a custom DNS service IP (`dns_service_ip`) and service CIDR (`service_cidr`). This is where you can input custom DNS settings.
- Finally, we export the `kube_config` which will allow you to interact with the Kubernetes cluster using `kubectl` once the deployment is complete.

Make sure to replace placeholder values (like `my-rg`, `my-aks-vnet`, `my-aks-cluster`, and `myaksdns`) with your actual resource names and settings. This code assumes that these resources do not exist and need to be created. If you already have a resource group or virtual network set up, you can reference them instead of creating new ones.

Furthermore, for specific AI development settings, you could add in configurations for things like GPU-based nodes, attach additional storage classes, or set up Azure Monitor for containers for logging and monitoring.

Adjustments to the DNS configuration or additional network configurations may require a deep understanding of how your AI applications will interact within the Kubernetes cluster and with external services. Always consider Azure's best practices for security, cost, and compliance when configuring your infrastructure.