Azure Kubernetes Service (AKS) has emerged as a leading container orchestration service, offering a plethora of features that streamline the deployment, management, and scaling of containerized applications. One of the standout aspects of AKS is its flexibility in offering both public and private clusters, as well as the powerful VNet integrations. In this guide, we’ll delve deep into these features, shedding light on their significance and benefits.

Overview of AKS and its key features

AKS is Microsoft Azure’s managed Kubernetes service. It takes away much of the complexity of deploying and managing Kubernetes clusters, allowing developers to focus on their applications. With features like automatic upgrades, monitoring, and scaling, AKS provides a robust environment for deploying containerized applications at scale.

Importance of securing your AKS cluster

With the increasing threats in the digital landscape, securing your AKS cluster is more crucial than ever.A secure AKS cluster not only protects sensitive data but also ensures uninterrupted service, safeguarding an organization’s reputation and trust. Several organizations have leveraged AKS’s public clusters, private clusters, and VNet integrations to optimize their deployments. These real-world examples underscore the tangible benefits of these features.

Importance of understanding public and private clusters and VNet integrations

Understanding the differences between public and private clusters, as well as the nuances of VNet integrations, is crucial for organizations aiming to optimize their AKS deployments. These configurations play a pivotal role in determining the accessibility, security, and network traffic flow of the AKS clusters.

Public Clusters in Azure Kubernetes Service

Public clusters in AKS are accessible from the internet, making them suitable for applications that require public accessibility.

Definition and benefits of public clusters

A public cluster has its API server exposed to the internet, allowing for easy access. The primary benefit is its accessibility from anywhere, making it ideal for applications that need to be publicly available. Additionally, public clusters often come with a reduced networking setup, simplifying the deployment process.

Let’s understand this design:

• Control Plane is exposed on public FQDN with public IP address.
• Control Plane endpoint is exposed to the internet.
• Authorized IP ranges: Whitelist IPs to access the control plane.

Use cases and scenarios for deploying public clusters

Public clusters are ideal for:

• Web applications that require public access.
• Development and testing environments where quick access is needed.
• Applications that don’t store sensitive data.

Step-by-step guide on creating a public cluster in AKS

Follow the below azure cli command to create a public cluster.

az group create -n rg-aks-public -l eastus
az aks create -n aks-cluster -g rg-aks-public
az aks show -n aks-cluster -g rg-aks-public --query fqdn
The behavior of this command has been altered by the following extension: aks-preview
"aks-cluste-rg-aks-public-5109b2-s5uvs0w2.hcp.eastus.azmk8s.io"

nslookup aks-cluste-rg-aks-public-5109b2-s5uvs0w2.hcp.eastus.azmk8s.io
Server:  UnKnown
Address:  2600:4040:a7d7:4600::1

Non-authoritative answer:
Name:    aks-cluste-rg-aks-public-5109b2-s5uvs0w2.hcp.eastus.azmk8s.io
Address:  52.152.250.203

Private Clusters in Azure Kubernetes Service

Private clusters offer an added layer of security by ensuring that the API server is not exposed to the internet.

Definition and advantages of private clusters

A private cluster’s API server is only accessible within a specific virtual network, ensuring that external traffic cannot access it. This setup offers enhanced security, making it ideal for sensitive applications or those bound by strict compliance requirements.

Let’s understand this design:

• Control Plane is exposed on public FQDN but with a private IP address.
• Control Plane endpoint is NOT exposed to the internet.
• Public FQDN could be disabled or enabled.
• Worker Nodes connect to the Control Plane through a Private Endpoint.
• Private FQDN is resolvable only through a Private DNS Zone.

Use cases and scenarios for deploying private clusters

Private clusters are best suited for:

• Applications that handle sensitive data.
• Production environments where security is paramount.
• Scenarios where strict network control is required.

Step-by-step guide on creating a private cluster in AKS

The below-mentioned azure cli will create a private cluster.

az group create -n rg-aks-private -l eastus  
az aks create -n aks-private-cluster -g rg-aks-private —enable-private-cluster 
az aks show -n aks-private-cluster -g rg-aks-private --query fqdn
The behavior of this command has been altered by the following extension: aks-preview
"aks-privat-rg-aks-private-5109b2-iv2m0chk.hcp.eastus.azmk8s.io"
# paste the fqdn coming from above command in nslookup
nslookup aks-privat-rg-aks-private-5109b2-iv2m0chk.hcp.eastus.azmk8s.io
Server:  UnKnown
Address:  2600:4040:a7d7:4600::1

*** No internal type for both IPv4 and IPv6 Addresses (A+AAAA) records available for aks-privat-rg-aks-private-5109b2-iv2m0chk.hcp.eastus.azmk8s.io

Public AKS cluster with VNet Integration in Azure Kubernetes Service

API Server VNet Integration is a powerful feature that enhances the security and flexibility of AKS deployments.Azure Kubernetes Service (AKS) offers the integration of public clusters with Azure Virtual Networks (VNet), enhancing the networking capabilities of containerized applications. This integration ensures that AKS clusters can seamlessly connect to existing Azure VNet resources, bolstering security by keeping traffic within the Azure network. Whether you’re deploying microservices or scaling applications, AKS with VNet integration provides a streamlined, secure, and efficient networking solution, minimizing external exposure and optimizing communication pathways.

Explanation of Public AKS cluster with VNet Integration and its significance

API Server VNet Integration allows the API server to be projected directly into a specific Azure VNet. This ensures that the traffic between the API server and the AKS nodes remains within the private network, enhancing security.

• Control Plane is exposed on public FQDN with a public IP address.
• The Control Plane endpoint is exposed to the internet.
• Public FQDN could NOT be disabled except on private clusters.
• DevOps CD pipelines could be accessed through public or private IPs.
• Worker Nodes access the Control Plane through the internal Load Balancer (private IP).
• AKS VNET Integration creates an internal Load Balancer.
• ILB private IP address is used to access the Control Plane.
• AKS VNET Integration creates a new Subnet in AKS VNET.
• It injects the ILB and configures delegation.

Steps to configure Public AKS cluster with VNet Integration

Please run the Azure CLI to create the public AKS cluster with VNet Integration.

az group create -n rg-aks-public-vnet-integration -l eastus
az extension add  --upgrade --name aks-preview --version 0.5.97
az feature register --namespace "Microsoft.ContainerService" --name "EnableAPIServerVnetIntegrationPreview"
az aks create -n aks-cluster -g rg-aks-public-vnet-integration --network-plugin azure --enable-apiserver-vnet-integration
az aks show -n aks-cluster -g rg-aks-public-vnet-integration —query -fqdn
# paste the fqdn coming from above command
nslookup 
az aks show -n aks-cluster -g rg-aks-public-vnet-integration —query privateFqdn
# get the credential of the cluster
az aks get-credentials -n aks-cluster -g rg-aks-public-vnet-integration
# service is exposed into private IP which is shown from the below mentioned commands. 
kubectl get svc
 
kubectl describe svc kubernetes

Benefits of using Public AKS cluster with VNet Integration in AKS

• Enhanced security by ensuring private network traffic.
• Flexibility in network configurations.
• Simplified network setup without the need for complex routing or firewall rules.

Private AKS cluster with VNet Integration in Azure Kubernetes Service

Private AKS clusters with VNet integration in Azure Kubernetes Service offer an elevated level of security and network optimization. By ensuring that the AKS cluster’s API server is accessible only within a designated Azure Virtual Network (VNet), it provides an isolated environment, safeguarding sensitive data and internal communications. This integration not only fortifies the cluster against external threats but also streamlines network traffic, allowing for efficient communication between the cluster and other Azure services, all while keeping the traffic confined to the private Azure network.

• Control Plane is exposed only on Private IP on the internal Load Balancer.
• Control Plane has public FQDN exposed to the internet.
• Public FQDN references a private IP and could be disabled.
• DevOps CD pipelines could only be accessed through private IP (internal LB).
• Nodes access the Control Plane through the internal Load Balancer (private IP).
• No Private Endpoint was created although the cluster is private.

Steps to create a Private cluster with VNet Integration

az group create -n rg-aks-private-vnet-integration -l eastus2  
az aks create -n aks-cluster -g rg-aks-private-vnet-integration —-enable-apiserver-vnet-integration -—enable-private-cluster
az aks show -n aks-cluster -g rg-aks-private-vnet-integration —query fqdn 

The difference between Private, Public, and VNet Integration

Here is the difference between public, private, and VNet integration.

Utilizing VNet integrations for enhanced security

VNet integrations in AKS provide an additional layer of security by ensuring that all traffic remains within the private network. This not only protects against external threats but also offers better control over network traffic.

Best practices for securing public and private clusters

• Regularly update and patch the AKS nodes.
• Implement strict access controls.
• Monitor the cluster for any suspicious activities.
• Use private clusters for sensitive applications.

FAQs (Frequently Asked Questions)

1. What are the main differences between public clusters and private clusters in Azure Kubernetes Service?
   • Public clusters are accessible from the internet, while private clusters restrict access to a specific VNet.
2. How does API Server VNet Integration enhance the security of Azure Kubernetes Service?
   • It ensures that all traffic between the API server and AKS nodes remains within the private network.
3. What are the best practices for securing an AKS cluster?
   • Regular updates, strict access controls, continuous monitoring, and using private clusters for sensitive applications are some of the best practices.
4. Can I switch from a public cluster to a private cluster in AKS without losing data or configurations?
   • Yes, but it requires careful planning and might involve some downtime. It’s always recommended to consult Azure’s official documentation or seek expert advice before making such changes.

For more content on Azure Kubernetes Services please refer to the Kubernetes blog on my website.

Conclusion

Azure Kubernetes Service offers a flexible and secure environment for deploying containerized applications. By understanding the nuances of public clusters, private clusters, and VNet integrations, organizations can optimize their AKS deployments, ensuring security, scalability, and efficiency.