Comparing Kubenet and Azure CNI - Choosing the Right Networking Option for Your AKS Cluster

Introduction:

When deploying an AKS (Azure Kubernetes Service) cluster, one critical decision you need to make is choosing the appropriate networking option. In this blog post, we will delve into a detailed comparison between Kubenet and Azure CNI (Container Networking Interface), two popular choices for networking in AKS. By understanding their features, benefits, and considerations, you can make an informed decision to ensure optimal network performance, security, and management for your AKS cluster.

Kubenet:

Kubenet is the default networking plugin for AKS clusters. It provides a simple and straightforward networking solution, suitable for many use cases. Let’s explore its key characteristics: 1.1. Node-based IP Assignments: With Kubenet, each node in the AKS cluster obtains an IP address from the Azure Virtual Network. Pods running on each node share the node’s IP address and are accessible via network address translation (NAT). This allows communication between pods on the same node.

Example: To create a 3-node AKS cluster using Kubenet, you can use the following Azure CLI command:

bash Copy code az aks create
–resource-group
–name
–node-count 3
–network-plugin kubenet
–generate-ssh-keys 1.2. Simplicity and Ease of Setup: Kubenet offers a hassle-free setup process, requiring minimal configuration. It’s an excellent choice for scenarios where basic networking requirements are sufficient, and simplicity is a priority.

Example: Once the AKS cluster with Kubenet networking is created, you can deploy applications using Kubernetes manifests or Helm charts without any specific networking configuration.

1.3. Limited Advanced Networking Features: While Kubenet provides basic networking capabilities, it lacks some advanced features. For example, network policies for fine-grained pod-to-pod communication control are not available with Kubenet. Additionally, direct pod-to-pod communication across nodes may require additional setup, such as configuring peering between virtual networks.

Example: Suppose you have two microservices that need to communicate with each other but require isolation from other services. With Kubenet, you can’t enforce network policies to restrict communication between these services.

Azure CNI:

Azure CNI, an alternative to Kubenet, offers more advanced networking capabilities and tighter integration with Azure infrastructure. Let’s explore its advantages: 2.1. Individual Pod IP Addresses: With Azure CNI, each pod in the AKS cluster receives an individual IP address, enabling direct communication between pods across nodes. This eliminates the need for NAT and enhances network performance.

Example: To create a 3-node AKS cluster using Azure CNI, you can use the following Azure CLI command:

bash Copy code az aks create
–resource-group
–name
–node-count 3
–network-plugin azure
–generate-ssh-keys 2.2. Improved Network Performance: Azure CNI leverages Azure’s virtual networking infrastructure, providing better network performance compared to Kubenet. It ensures efficient communication between pods, reducing latency and maximizing throughput.

Example: When deploying applications in an Azure CNI-enabled AKS cluster, the pods can communicate directly with each other using their individual IP addresses, resulting in lower network latency and improved overall performance.

2.3. Advanced Networking Features: Azure CNI supports a range of advanced networking features, providing more flexibility and control over your AKS cluster networking.

2.3.1. Routing: With Azure CNI, you can configure routing within your AKS cluster by utilizing Azure Route Tables. By associating a route table with the subnet used by your AKS cluster, you can define custom routes for traffic within the cluster or outbound connectivity.

2.3.2. Network Security Groups (NSGs): Azure CNI integrates with Azure Network Security Groups (NSGs) to enforce granular network-level security policies. NSGs allow you to define inbound and outbound security rules based on IP addresses, ports, and protocols, adding an extra layer of security to your AKS cluster.

2.3.3. Private Endpoints: Azure CNI supports Private Endpoints, which enable private access to your AKS cluster from virtual networks or other services within Azure. This ensures secure communication without exposing your AKS cluster to the public internet.

2.3.4. Connectivity to Other Azure and Clouds: Azure CNI provides connectivity options to other Azure services and cloud environments. You can establish peering connections between virtual networks to enable communication between AKS clusters and other Azure resources. Additionally, Azure CNI supports multi-region and hybrid cloud scenarios, allowing you to connect your AKS cluster to on-premises networks or other cloud providers using VPN or ExpressRoute.

##Common Troubleshooting for Kubenet and Azure CNI:

Kubenet:

If pods cannot communicate across nodes, ensure that the necessary network configuration, such as virtual network peering, is in place to enable node-to-node communication. Troubleshoot any network address translation (NAT) issues that may arise, such as conflicts with IP address ranges or network connectivity problems. If network policies are required, consider using a network policy add-on like Calico to provide the necessary pod-to-pod communication control.

Azure CNI:

If pods are unable to communicate across nodes, verify that the necessary Azure networking components, such as route tables and network security groups (NSGs), are correctly configured. Ensure that the pod IP addresses are within the subnet range and that there are no conflicts or overlapping IP addresses. Troubleshoot any connectivity issues between the AKS cluster and other Azure resources, such as virtual network peering or VPN/ExpressRoute connectivity.

Conclusion:

Choosing the right networking option for your AKS cluster is crucial to ensure optimal network performance, security, and management. While Kubenet offers simplicity and ease of setup, Azure CNI provides advanced features, improved network performance, and seamless integration with Azure infrastructure.

If your use case requires advanced networking capabilities such as routing, private endpoints, and integration with Azure networking services, Azure CNI is generally the recommended choice. However, if basic networking functionality is sufficient and simplicity is a priority, Kubenet can be a suitable option.

Consider your specific requirements, such as security, performance, scalability, and integration with Azure services, when making the decision. Evaluate the trade-offs and align them with your application’s needs to achieve the best networking solution for your AKS cluster.

Remember, both Kubenet and Azure CNI have their strengths, and the choice ultimately depends on your unique use case and goals.

User How does ingress work for both approaches, is it the same? ChatGPT When it comes to handling Ingress in AKS, there are some differences between Kubenet and Azure CNI. Let’s explore how Ingress works for both approaches:

Kubenet: In a Kubenet-based AKS cluster, Ingress is typically implemented using an Ingress controller, such as Nginx or Traefik, deployed as a separate pod within the cluster. The Ingress controller acts as an entry point for incoming traffic and routes it to the appropriate services based on the defined Ingress rules. The Ingress controller listens for incoming requests on a specified host and port, typically port 80 or 443 for HTTP and HTTPS traffic. It then forwards the requests to the corresponding backend services based on the defined rules in the Ingress resource.

Example: To deploy an Nginx Ingress controller in a Kubenet-based AKS cluster, you can use the following command:

bash Copy code kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.0.0/deploy/static/provider/cloud/deploy.yaml Once the Ingress controller is deployed, you can define Ingress resources using YAML manifests to specify the routing rules for incoming traffic.

Azure CNI: In an Azure CNI-enabled AKS cluster, Ingress is handled through the Azure Application Gateway, which serves as the entry point for external traffic. The Application Gateway provides layer 7 load balancing and allows you to define routing rules, SSL termination, and other advanced features. To expose your services to external traffic using Azure CNI, you need to create an Ingress resource that references the Application Gateway. The Ingress resource specifies the routing rules for incoming requests, including host-based routing, path-based routing, and SSL termination.

Example: To create an Ingress resource with Azure CNI, you can use the following YAML manifest:

yaml Copy code apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: my-ingress annotations: kubernetes.io/ingress.class: azure/application-gateway spec: rules:

host: mydomain.com http: paths:
- path: / pathType: Prefix backend: service: name: my-service port: number: 80 The above example configures the Ingress resource to route traffic with the host “mydomain.com” to the backend service “my-service” on port 80.

In summary, while both Kubenet and Azure CNI support Ingress in AKS clusters, the underlying implementation differs. Kubenet relies on an Ingress controller running as a separate pod within the cluster, while Azure CNI utilizes the Azure Application Gateway as the entry point for external traffic.