Announcing public preview: Cilium mTLS encryption for Azure Kubernetes Service
We are thrilled to announce the public preview of Cilium mTLS encryption in Azure Kubernetes Service (AKS), delivered as part of Advanced Container Networking Services and powered by the Azure CNI dataplane built on Cilium. This capability is the result of a close engineering collaboration between Microsoft and Isovalent (now part of Cisco). It brings transparent, workload‑level mutual TLS (mTLS) to AKS without sidecars, without application changes, and without introducing a separate service mesh stack. This public preview represents a major step forward in delivering secure, high‑performance, and operationally simple networking for AKS customers. In this post, we’ll walk through how Cilium mTLS works, when to use it, and how to get started. Why Cilium mTLS encryption matters Traditionally, teams looking to in-transit traffic encryption in Kubernetes have had two primary options: Node-level encryption (for example, WireGuard or virtual network encryption), which secures traffic in transit but lacks workload identity and authentication. Service meshes, which provide strong identity and mTLS guarantees but introduce operational complexity. This trade‑off has become increasingly problematic, as many teams want workload‑level encryption and authentication, but without the cost, overhead, and architectural impact of deploying and operating a full-service mesh. Cilium mTLS closes this gap directly in the dataplane. It delivers transparent, inline mTLS encryption and authentication for pod‑to‑pod TCP traffic, enforced below the application layer. And implemented natively in the Azure CNI dataplane built on Cilium, so customers gain workload‑level security without introducing a separate service mesh, resulting in a simpler architecture with lower operational overhead. To see how this works under the hood, the next section breaks down the Cilium mTLS architecture and follows a pod‑to‑pod TCP flow from interception to authentication and encryption. Architecture and design: How Cilium mTLS works Cilium mTLS achieves workload‑level authentication and encryption by combining three key components, each responsible for a specific part of the authentication and encryption lifecycle. Cilium agent: Transparent traffic interception and wiring Cilium agent which already exists on any cluster running with Azure CNI powered by cilium, is responsible for making mTLS invisible to applications. When a namespace is labelled with “io.cilium/mtls-enabled=true”, The Cilium agent enrolls all pods in that namespace. It enters each pod's network namespace and installs iptables rules that redirect outbound traffic to ztunnel on port 15001. It is also responsible for passing workload metadata (such as pod IP and namespace context) to ztunnel. Ztunnel: Node‑level mTLS enforcement Ztunnel is an open source, lightweight, node‑level Layer 4 proxy that was originally created by Istio. Ztunnel runs as a DaemonSet, on the source node it looks up the destination workload via XDS (streamed from the Cilium agent) and establishes mutually authenticated TLS 1.3 sessions between source and destination nodes. Connections are held inline until authentication is complete, ensuring that traffic is never sent in plaintext. The destination ztunnel decrypts the traffic and delivers it into the target pod, bypassing the interception rules via an in-pod mark. The application sees a normal plaintext connection — it is completely unaware encryption happened. SPIRE: Workload identity and trust SPIRE (SPIFFE Runtime Environment) provides the identity foundation for Cilium mTLS. SPIRE acts as the cluster Certificate Authority, issuing short‑lived X.509 certificates (SVIDs) that are automatically rotated and validated. This is a key design principle of Cilium mTLS - trust is based on workload identity, not network topology. Each workload receives a cryptographic identity derived from: Kubernetes namespace Kubernetes ServiceAccount These identities are issued and rotated automatically by SPIRE and validated on both sides of every connection. As a result: Identity remains stable across pod restarts and rescheduling Authentication is decoupled from IP addresses Trust decisions align naturally with Kubernetes RBAC and namespace boundaries This enables a zero‑trust networking model that fits cleanly into existing AKS security practices. End‑to‑End workflow example To see how these components work together, consider a simple pod‑to‑pod connection: A pod initiates a TCP connection to another pod. Traffic intercepted inside the pod network namespace and redirected to the local ztunnel instance. ztunnel retrieves the workload identity using certificates issued by SPIRE. ztunnel establishes a mutually authenticated TLS session with the destination node’s ztunnel. Traffic is encrypted and sent between pods. The destination ztunnel decrypts the traffic and delivers it to the target pod. Every packet from an enrolled pod is encrypted. There is no plaintext window, and no dropped first packets. The connection is held inline by ztunnel until the mTLS tunnel is established, then traffic flows bidirectionally through an HBONE (HTTP/2 CONNECT) tunnel. Workload enrolment and scope Cilium mTLS in AKS is opt‑in and scoped at the namespace level. Platform teams enable mTLS by applying a single label to a namespace. From that point on: All pods in that namespace participate in mTLS Authentication and encryption are mandatory between enrolled workloads Non-enrolled namespaces continue to operate unchanged Encryption is applied only when both pods are enrolled. Traffic between enrolled and non‑enrolled workloads continues in plaintext without causing connectivity issues or hard failures. This model enables gradual rollout, staged migrations, and low-risk adoption across environments. Getting started in AKS Cilium mTLS encryption is available in public preview for AKS clusters that use: Azure CNI powered by Cilium Advanced Container Networking Services You can enable mTLS: When creating a new cluster, or On an existing cluster by updating the Advanced Container Networking Services configuration Once enabled, enrolling workloads is as simple as labelling a namespace. 👉 Learn more Concepts: How Cilium mTLS works, architecture, and trust boundaries How-to guide: Step-by-step instructions to enable and verify mTLS in AKS Looking ahead This public preview represents an important step forward in simplifying network security for AKS and reflects a deep collaboration between Microsoft and Isovalent to bring open, standards‑based innovation into production‑ready cloud platforms. We’re continuing to work closely with the community to improve the feature and move it toward general availability. If you’re looking for workload‑level encryption without the overhead of a traditional service mesh, we invite you to try Cilium mTLS in AKS and share your experience.
Introducing eBPF Host Routing: High performance AI networking with Azure CNI powered by Cilium
AI-driven applications demand low-latency workloads for optimal user experience. To meet this need, services are moving to containerized environments, with Kubernetes as the standard. Kubernetes networking relies on the Container Network Interface (CNI) for pod connectivity and routing. Traditional CNI implementations use iptables for packet processing, adding latency and reducing throughput. Azure CNI powered by Cilium natively integrates Azure Kubernetes service (AKS) data plane with Azure CNI networking modes for superior performance, hardware offload support, and enterprise-grade reliability. Azure CNI powered by Cilium delivers up to 30% higher throughput in both benchmark and real-world customer tests compared to a bring-your-own Cilium setup on AKS. The next leap forward: Now, AKS data plane performance can be optimized even further with eBPF host routing, which is an open-source Cilium CNI capability that accelerates packet forwarding by executing routing logic directly in eBPF. As shown in the figure, this architecture eliminates reliance on iptables and connection tracking (conntrack) within the host network namespace. As a result, significantly improving packet processing efficiency, reducing CPU overhead and optimized performance for modern workloads. Comparison of host routing using the Linux kernel stack vs eBPF Azure CNI powered by Cilium is battle-tested for mission-critical workloads, backed by Microsoft support, and enriched with Advanced Container Networking Services features for security, observability, and accelerated performance. eBPF host routing is now included as part of Advanced Container Networking Services suite, delivering network performance acceleration. In this blog, we highlight the performance benefits of eBPF host routing, explain how to enable it in an AKS cluster, and provide a deep dive into its implementation on Azure. We start by examining AKS cluster performance before and after enabling eBPF host routing. Performance comparison Our comparative benchmarks measure the difference in Azure CNI Powered by Cilium, by enabling eBPF host routing. To perform these measurements, we use AKS clusters on K8s version 1.33, with host nodes of 16 cores, running Ubuntu 24.04. We are interested in throughput and latency numbers for pod-to-pod traffic in these clusters. For throughput measurements, we deploy netperf client and server pods, and measure TCP_STREAM throughput at varying message sizes in tests running 20 seconds each. The wide range of message sizes are meant to capture the variety of workloads running on AKS clusters, ranging from AI training and inference to messaging systems and media streaming. For latency, we run TCP_RR tests, measuring latency at various percentiles, as well as transaction rates. The following figure compares pods on the same node; eBPF-based routing results in a dramatic improvement in throughput (~30%). This is because, on the same node, the throughput is not constrained by factors such as the VM NIC limits and is almost entirely determined by host routing performance. For pod-to-pod throughput across different nodes in the cluster. eBPF host routing results in better pod-to-pod throughput across nodes, and the difference is more pronounced with smaller message sizes (3x more). This is because, with smaller messages, the per-message overhead incurred in the host network stack has a bigger impact on performance. Next, we compare latency for pod-to-pod traffic. We limit this benchmark to intra-node traffic, because cross-node traffic latency is determined by factors other than the routing latency incurred in the hosts. eBPF host routing results in reduced latency compared to the non-accelerated configuration at all measured percentiles. We have also measured the transaction rate between client and server pods, with and without eBPF host routing. This benchmark is an alternative measurement of latency because a transaction is essentially a small TCP request/response pair. We observe that eBPF host routing improves transactions per second by around 27% as compared to legacy host routing. Transactions/second (same node) Azure CNI configuration Transactions/second eBPF host routing 20396.9 Traditional host routing 16003.7 Enabling eBPF routing through Advanced Container Networking Services eBPF host routing is disabled by default in Advanced Container Networking Services because bypassing iptables in the host network namespace can ignore custom user rules and host-level security policies. This may lead to visible failures such as dropped traffic or broken network policies, as well as silent issues like unintended access or missed audit logs. To mitigate these risks, eBPF host routing is offered as an opt-in feature, enabled through Advanced Container Networking Services on Azure CNI powered by Cilium. The Advanced Container Networking Services advantage: Built-in safeguards: Enabling eBPF Host Routing in ACNS enhances the open-source offering with strong built-in safeguards. Before activation, ACNS validates existing iptables rules in the host network namespace and blocks enablement if user-defined rules are detected. Once enabled, kernel-level protections prevent new iptables rules and generate Kubernetes events for visibility. These measures allow customers to benefit from eBPF’s performance gains while maintaining security and reliability. Thanks to the additional safeguards, eBPF host routing in Advanced Container Networking Services is a safer and more robust option for customers who wish to obtain the best possible networking performance on their Kubernetes infrastructure. How to enable eBPF Host Routing with ACNS Visit the documentation on how to enable eBPF Host Routing for new and existing Azure CNI Powered by Cilium clusters. Verify the network profile with the new performance `accelerationMode`field set to `BpfVeth`. "networkProfile": { "advancedNetworking": { "enabled": true, "performance": { "accelerationMode": "BpfVeth" }, … For more information on Advanced Container Networking Services and ACNS Performance, please visit https://aka.ms/acnsperformance. Resources For more info about Advanced Container Networking Services please visit (Container Network Security with Advanced Container Networking Services (ACNS) - Azure Kubernetes Service | Microsoft Learn). For more info about Azure CNI Powered by Cilium please visit (Configure Azure CNI Powered by Cilium in Azure Kubernetes Service (AKS) - Azure Kubernetes Service | Microsoft Learn).
Simplify container network metrics filtering in Azure Container Networking Services for AKS
We’re excited to introduce container network metrics filtering in Azure Container Networking Services for Azure Kubernetes Service (AKS) is now in public preview! This capability transforms how you manage network observability in Kubernetes clusters by giving you control over what metrics matter most. Why excessive metrics are a problem (and how we’re fixing it) In today’s large-scale, microservices-driven environments, teams often face metrics bloat, collecting far more data than they need. The result? High storage & ingestion costs: Paying for data you’ll never use. Cluttered dashboards: Hunting for critical latency spikes in a sea of irrelevant pod restarts. Operational overhead: Slower queries, higher maintenance, and fatigue. Our new filtering capability solves this by letting you define precise filters at the pod level using standard Kubernetes custom resources. You collect only what matters, before it ever reaches your monitoring stack. Key Benefits: Signal Over Noise Benefit Your Gain Fine-grained control Filter by namespace or pod label. Target critical services and ignore noise. Cost optimization Reduce ingestion costs for Prometheus, Grafana, and other tools. Improved observability Cleaner dashboards and faster troubleshooting with relevant metrics only. Dynamic & zero-downtime Apply or update filters without restarting Cilium agents or Prometheus. How it works: Filtering at the source Unlike traditional sampling or post-processing, filtering happens at the Cilium agent level—inside the kernel’s data plane. You define filters using the ContainerNetworkMetric custom resource to include or exclude metrics such as: DNS lookups TCP connection metrics Flow metrics Drop (error) metrics This reduces data volume before metrics leave the host, ensuring your observability tools receive only curated, high-value data. Example: Filtering flow metrics to reduce noise Here’s a sample ContainerNetworkMetric CRD that filters only dropped flows from the traffic/http namespace and excludes flows from traffic/fortio pods: apiVersion: acn.azure.com/v1alpha1 kind: ContainerNetworkMetric metadata: name: container-network-metric spec: filters: - metric: flow includeFilters: # Include only DROPPED flows from traffic namespace verdict: - "dropped" from: namespacedPod: - "traffic/http" excludeFilters: # Exclude traffic/fortio flows to reduce noise from: namespacedPod: - "traffic/fortio" Before filtering: After applying filters: Getting started today Ready to simplify your network observability? Enable Advanced Container Networking Services: Make sure Advanced Container Networking Services is enabled on your AKS cluster. Define Your Filter: Apply the ContainerNetworkMetric CRD with your include/exclude rules. Validate: Check your settings via ConfigMap and Cilium agent logs. See the Impact: Watch ingestion costs drop and dashboards become clearer! 👉 Learn more in the Metrics Filtering Guide. Try the public preview today and take control of your container network metrics.Layer 7 Network Policies for AKS: Now Generally Available for Production Security and Observability!
We are thrilled to announce that Layer 7 (L7) Network Policies for Azure Kubernetes Service (AKS), powered by Cilium and Advanced Container Networking Services (ACNS), has reached General Availability (GA)! The journey from public preview to GA signifies a critical step: L7 Network Policies are now fully supported, highly optimized, and ready for your most demanding, mission-critical production workloads. A Practical Example: Securing a Multi-Tier Retail Application Let's walk through a common production scenario. Imagine a standard retail application running on AKS with three core microservices: frontend-app: Handles user traffic and displays product information. inventory-api: A backend service that provides product stock levels. It should be read-only for the frontend. payment-gateway: A highly sensitive service that processes transactions. It should only accept POST requests from the frontend to a specific endpoint. The Security Challenge: A traditional L4 policy would allow the frontend-app to talk to the inventory-api on its port, but it couldn't prevent a compromised frontend pod from trying to exploit a potential vulnerability by sending a DELETE or POST request to modify inventory data. The L7 Policy Solution: With GA L7 policies, you can enforce the Principle of Least Privilege at the application layer. Here's how you would protect the inventory-api: apiVersion: cilium.io/v2 kind: CiliumNetworkPolicy metadata: name: protect-inventory-api spec: endpointSelector: matchLabels: app: inventory-api ingress: - fromEndpoints: - matchLabels: app: frontend-app toPorts: - ports: - port: "8080" # The application port protocol: TCP rules: http: - method: "GET" # ONLY allow the GET method path: "/api/inventory/.*" # For paths under /api/inventory/ The Outcome: Allowed: A legitimate request from the frontend-app (GET /api/inventory/item123) is seamlessly forwarded. Blocked: Assuming frontend-app is compromised, any malicious request (like DELETE /api/inventory/item123) originating from it is blocked at the network layer. This Zero Trust approach protects the inventory-api service from the threat, regardless of the security state of the source service. This same principle can be applied to protect the payment-gateway, ensuring it only accepts POST requests to the /process-payment endpoint, and nothing else. Beyond L7: Supporting Zero Trust with Enhanced Security In addition, toL7 application-level policies to ensure Zero Trust, we support Layer 3/4 network security and advanced egress controls like Fully Qualified Domain Name (FQDN) filtering. This comprehensive approach allows administrators to: Restrict Outbound Connections (L3/L4 & FQDN): Implement strict egress control by ensuring that workloads can only communicate with approved external services. FQDN filtering is crucial here, allowing pods to connect exclusively to trusted external domains (e.g., www.trusted-partner.com), significantly reducing the risk of data exfiltration and maintaining compliance. To learn more, visit the FQDN Filtering Overview. Enforce Uniform Policy Across the Cluster (CCNP): Extend protections beyond individual namespaces. By defining security measures as a Cilium Clusterwide Network Policy (CCNP), thanks to its General Availability (GA), administrators can ensure uniform policy enforcement across multiple namespaces or the entire Kubernetes cluster, simplifying management and strengthening the overall security posture of all workloads. To learn CCNP Example: L4 Egress Policy with FQDN Filtering This policy ensures that all pods across the cluster (CiliumClusterwideNetworkPolicy) are only allowed to establish outbound connections to the domain *.example.com on the standard web ports (80 and 443). apiVersion: cilium.io/v2 kind: CiliumClusterwideNetworkPolicy metadata: name: allow-egress-to-example-com spec: endpointSelector: {} # Applies to all pods in the cluster egress: - toFQDNs: - matchPattern: "*.example.com" # Allows access to any subdomain of example.com toPorts: - ports: - port: "443" protocol: TCP - port: "80" protocol: TCP Operational Excellence: Observability You Can Trust A secure system must be observable. With GA, the integrated visibility of your L7 traffic is production ready. In our example above, the blocked DELETE request isn't silent. It is immediately visible in your Azure Managed Grafana dashboards as a "Dropped" flow, attributed directly to the protect-inventory-api policy. This makes security incidents auditable and easy to diagnose, enabling operations teams to detect misconfigurations or threats in real time. Below is a sample dashboard layout screenshot. Next Steps: Upgrade and Secure Your Production! We encourage you to enable L7 Network Policies on your AKS clusters and level up your network security controls for containerized workloads. We value your feedback as we continue to develop and improve this feature. Please refer to the Layer 7 Policy Overview for more information and visit How to Apply L7 Policy for an example scenario.
Introducing WireGuard In-Transit Encryption for AKS (Public Preview)
As organizations continue to scale containerized workloads in Azure Kubernetes Service (AKS), the need to secure network traffic between applications and services has never been more critical especially in regulated or security-sensitive environments. We’re excited to announce the public preview of WireGuard-based in-transit encryption in AKS, a new capability in Advanced Container Networking Services that enhances inter-node traffic protection with minimal operational overhead. What is WireGuard? WireGuard is a modern, high-performance VPN protocol known for its simplicity, and robust cryptography. Integrated into the Cilium data plane and managed as part of AKS networking, WireGuard offers an efficient way to encrypt traffic transparently within your cluster. With this new feature, WireGuard is now natively supported as part of Azure CNI powered by Cilium with Advanced Container Networking services, no need for third-party encryption tools or custom key management systems. What Gets Encrypted? The WireGuard integration in AKS focuses on the most critical traffic path: ✅ Encrypted: Inter-node pod traffic: Network communication between pods running on different nodes in the AKS cluster. This traffic traverses the underlying network infrastructure and is encrypted using WireGuard to ensure confidentiality and integrity. ❌ Not encrypted: Same-node pod traffic: Communication between pods that are running on the same node. Since this traffic does not leave the node, it bypasses WireGuard and remains unencrypted. Node-generated traffic: Traffic initiated by the node itself, which is currently not routed through WireGuard and thus not encrypted. This scope strikes the right balance between strong protection and performance by securing the most critical traffic, which is data that leaves the host and traverses the network. Key Benefits Simple Configuration: Enable WireGuard with just a few flags during AKS cluster creation or update. Automatic Key Management: Each node generates and exchanges WireGuard keys automatically—no need for manual configuration. Transparent to Applications: No application-level changes are required. Encryption happens at the network layer. Cloud-Native Integration: Fully managed as part of Advanced Container Networking Services and Cilium, offering a seamless and reliable experience Architecture: How It Works When WireGuard is enabled: Each node generates a unique public/private key pair. The public keys are securely shared between nodes via the CiliumNode custom resource. A dedicated network interface (cilium_wg0) is created and managed by the Cilium agent running on each node. Peers are dynamically updated, and keys are rotated automatically every 120 seconds to minimize risk. This mechanism ensures that only validated nodes can participate in encrypted communication. WireGuard and VNet Encryption AKS now offers two powerful in-transit encryption options: Feature WireGuard Encryption VNet Encryption Scope Pod-to-pod inter-node traffic All traffic in the VNet VM Support Works on all VM SKUs Requires hardware support (e.g., Gen2 VMs) Deployment Flexibility Cloud-agnostic, hybrid ready Azure-only Performance Software-based, moderate CPU usage Hardware-accelerated, low overhead Choose WireGuard if you want encryption flexibility across clouds or have VM SKUs that don’t support VNet encryption . Choose VNet Encryption for full-network coverage and ultra-low CPU overhead. Conclusion and Next Steps WireGuard in AKS, now in public preview, delivers strong encryption that protects traffic as it leaves the host and traverses the network right where it's needed most. It offers a balanced approach to securing container networking without compromising usability. Ready to get started? Check out our how-to guide for step-by-step instructions on enabling WireGuard in your cluster and securing your container networking with ease. Explore more about Advanced Container Networking Services: Container Network Observability L7 network policies FQDN-based Policy
Azure CNI Overlay for Application Gateway for Containers and Application Gateway Ingress Controller
What are Azure CNI Overlay and Application Gateway? Azure CNI Overlay leverages logical network spaces for pod IP assignment management (IPAM). This provides enhanced IP scalability with reduced management responsibilities. Application Gateway for Containers is the latest and most recommended container L7 load-balancing solution. It introduces a new scalable control plane and data plane to address the performance demands and modern workloads being deployed to AKS clusters on Azure. Azure network control plane configures routing between Application Gateway and overlay pods. Why is the feature needed? As businesses increasingly use containerized solutions, managing container networks at scale has become a priority. Within container network management, IP address exhaustion, scalability and application load balancing performance are highly requested and discussed in many forums. Azure CNI Overlay is the default container networking IPAM mode on AKS. In the overlay design, AKS nodes use IPs from Azure virtual network (VNet) IP address range and pods are addressed from an overlay IP address range. The overlay pods can communicate with each other directly via a different routing domain. Overlay IP addresses can be reused across multiple clusters in the same VNet, provisioning a solution for IP exhaustion and increasing IP scale to over 1M. Azure CNI Overlay supporting Application Gateway for Containers provides customers with a more performant, reliable, and scalable container networking solution. Meanwhile, Azure CNI Overlay supporting AGIC provides customers with full feature parity if they choose to upgrade AKS clusters from kubenet to Azure CNI Overlay. Key Benefits High scale with Azure CNI Overlay combined with a high-performance ingress solution Azure CNI Overlay provides direct pod to pod routing with high IP scale using direct azure native routing with no encapsulation overhead. IPs can be reused across clusters in the same VNET allowing customers to conserve IP addresses. Application Gateway for Containers is the latest and most recommended container L7 load-balancing solution. Installing Application Gateway for Containers on AKS clusters with Azure CNI Overlay provides customers with the best solution combination of IP scalability and ingress solution on Azure. Feature parity between kubenet and Azure CNI Overlay With the retirement announcement of kubenet, we expect to see customers upgrade their AKS container networking solution from kubenet to Azure CNI Overlay soon. This feature allows customers to maintain business continuity during the transitioning process. Learn More Read more about Azure CNI Overlay and Application Gateway for Containers. Learn more on how to upgrade AKS clusters’ IPAM to Azure CNI Overlay. Learn more about Azure Kubernetes Service and Application Gateway.Provide a Flat Network Scaling Solution to AKS - Azure CNI Pod Subnet - Static Block Allocation
We are excited to announce the general availability of Azure CNI Pod Subnet - Static Block Allocation – a networking solution that transforms how you scale Azure Kubernetes Service (AKS) clusters! This long-awaited feature is now here, providing enterprise-grade flat networking for clusters in unprecedented capacity. What is Azure CNI Pod Subnet - Static Block Allocation? Azure CNI Pod Subnet - Static Block Allocation revolutionizes AKS networking by expanding cluster capacity from 65K to 1M pods – a game-changing 15x increase that eliminates traditional scaling barriers. Instead of assigning a batch of random individual IP addresses to each node, this innovative approach assigns dedicated Azure subnet CIDR ranges directly to nodes. Every pod scheduled on a node receives its IP address from that node's pre-allocated CIDR block, raising IP limit and simplifying massive deployments. The result is you gain unmatched flexibility with separate node and pod subnets, granular control over NAT and NSG policies, isolated workloads at the pod level, and VNet-native pod networking that maintains peak performance. It also seamlessly works with Azure CNI Powered by Cilium to provide advanced networking capabilities and comprehensive network policy enforcement. Why is Azure CNI Pod Subnet - Static Block Allocation needed? Kubernetes network solutions are challenging to plan due to rapidly evolving business needs. AKS users often face difficulties balancing simplicity, security, and scalability, while environmental changes further increase management costs. Many AKS users need a flat network architecture, pods with direct inbound connectivity, and Azure-native solution integrations, but traditional flat networks couldn't scale beyond 65K pods. Until the launch of static block, customers either choose overlay networks to achieve massive scale or sacrifice the benefits of flat networking. Azure CNI Pod Subnet - Static Block Allocation enables VNet-routed IP addresses that can scale to over 1M pods, providing the simplicity and low latency of a flat network. Each node receives pre-allocated CIDR blocks, and all pods on that node obtain IP addresses from these ranges. This approach delivers massive scale, previously only available with overlay networks (up to 1M pods) while maintaining all the benefits of a flat network architecture. It also works seamlessly alongside Azure CNI Pod Subnet - Dynamic IP Allocation, simply deploy it on new node pools with dedicated subnets. AKS users can scale up AKS network solutions with minimal effort while maintaining enterprise-grade reliability and security. Key Benefits That Matter to You Massive Scale Increase: Break through the 65K pod limitation and scale up to 1M pods per cluster. This isn't just a number—it's about giving you the freedom to build and scale without hitting unexpected networking limits. High Performance: AKS users’ pods get routed on the VNet which is a benefit for ingress/egress, eliminating unnecessary network hops and reducing latency for VNet-native pod networking. Efficient IP Management: AKS users now can allocate CIDR blocks to nodes. This approach raises the IP scalability limit for large-scale deployments. Unmatched Flexibility: Work seamlessly with existing clusters with Azure CNI Pod Subnet - Dynamic IP Allocation Share pod subnets across multiple node pools or even different clusters. Scale your node and pod networks independently Granular Control and Security: Since pods get their own dedicated subnet, AKS users can: Apply different network security policies to pods vs. nodes. Configure customized NAT and NSG policies. Implement isolated workloads at the pod level. Learn more about Azure CNI Pod Subnet - Static Block Allocation Read more in Azure CNI Pod Subnet - Static Block Allocation and try it out in your environment today. Learn more about the solution limitations. Learn more about Azure Kubernetes Service.
Accelerate designing, troubleshooting & securing your network with Gen-AI powered tools, now GA.
We are thrilled to announce the general availability of Azure Networking skills in Copilot, an extension of Copilot in Azure and Security Copilot designed to enhance cloud networking experience. Azure Networking Copilot is set to transform how organizations design, operate, and optimize their Azure Network by providing contextualized responses tailored to networking-specific scenarios and using your network topology.Introducing Container Network Logs with Advanced Container Networking Services for AKS
Overview of container network logs Container network logs offer a comprehensive way to monitor network traffic in AKS clusters. Two modes of support, stored-logs and on-demand logs, provides debugging flexibility with cost optimization. The on-demand mode provides a snapshot of logs with queries and visualization with Hubble CLI UI for specific scenarios and does not use log storage to persist the logs. The stored-logs mode when enabled continuously collects and persists logs based on user-defined filters. Logs can be stored either in Azure Log Analytics (managed) or locally (unmanaged). Managed storage: Logs are forwarded to Azure Log Analytics for secure, scalable, and compliant storage. This enables advanced analytics, anomaly detection, and historical trend analysis. Both basic and analytics table plans are supported for storage. Unmanaged storage: Logs are stored locally on the host nodes under /var/log/acns/hubble. These logs are rotated automatically at 50 MB to manage storage efficiently. These logs can be exported to external logging systems or collectors for further analysis. Use cases Connectivity monitoring: Identify and visualize how Kubernetes workloads communicate within the cluster and with external endpoints, helping to resolve application connectivity issues efficiently. Troubleshooting network errors: Gain deep granular visibility into dropped packets, misconfigurations, or errors with details on where and why errors are occurring (TCP/UDP, DNS, HTTP) for faster root cause analysis. Security policy enforcement: Detect and analyze suspicious traffic patterns to strengthen cluster security and ensure regulatory compliance. How it works Container network logs use eBPF technology with Cilium to capture network flows from AKS nodes. Log collection is disabled by default. Users can enable log collection by defining custom resources (CRs) to specify the types of traffic to monitor, such as namespaces, pods, services, or protocols. The Cilium agent collects and processes this traffic, storing logs in JSON format. These logs can either be retained locally or integrated with Azure Monitoring for long-term storage and advanced analytics and visualization with Azure managed Grafana. Fig1: Container network logs overview If using managed storage, users will enable Azure monitor log collection using Azure CLI or ARM templates. Here’s a quick example of enabling container network logs on Azure monitor using the CLI: az aks enable-addons -a monitoring --enable-high-log-scale-mode -g $RESOURCE_GROUP -n $CLUSTER_NAME az aks update --enable-acns \ --enable-retina-flow-logs \ -g $RESOURCE_GROUP \ -n $CLUSTER_NAME Key benefits Faster issue resolution: Detailed logs enable quick identification of connectivity and performance issues. Operational efficiency: Advanced filtering reduces data management overhead. Enhanced application reliability: Proactive monitoring ensures smoother operations. Cost optimization: Customized logging scopes minimize storage and data ingestion costs. Streamlined compliance: Comprehensive logs support audits and security requirements. Observing logs in Azure managed Grafana dashboards Users can visualize container network logs in Azure managed Grafana dashboards, which simplify monitoring and analysis: Flow logs dashboard: View internal communication between Kubernetes workloads. This dashboard highlights metrics such as total requests, dropped packets, and error rates. Error logs dashboard: Easily zoom in only on the logs which show errors for faster log parsing. Service dependency graph: Visualize relationships between services, detect bottlenecks, and optimize network flows. These dashboards provide filtering options to isolate specific logs, such as DNS errors or traffic patterns, enabling efficient root cause analysis. Summary statistics and top-level metrics further enhance understanding of cluster health and activity. Fig 2: Azure managed Grafana dashboard for container network logs Conclusion Container network logs for AKS offer a powerful and cost optimized way to monitor and analyze network activity, enhance troubleshooting, security, and ensure compliance. To get started, enable Advanced Container Networking Services in your AKS cluster and configure custom resources for logging. Visualize your logs in Grafana dashboards and Azure Log Analytics to unlock actionable insights. Learn more here.Azure CNI now supports Node Subnet IPAM mode with Cilium Dataplane
Azure CNI Powered by Cilium is a high-performance data plane leveraging extended Berkeley Packet Filter (eBPF) technologies to enable features such as network policy enforcement, deep observability, and improved service routing. Legacy CNI supports Node Subnet where every pod gets an IP address from a given subnet. AKS clusters that require VNet IP addressing mode (non-overlay scenarios) are typically advised to use Pod Subnet mode. However, AKS clusters that do not face the risk of IP exhaustion can continue to use node subnet mode for legacy reasons and switch the CNI dataplane to utilize Cilium's features. With this feature launch, we are providing that migration path! Users often leverage node subnet mode in Azure Kubernetes Service (AKS) clusters for ease of use. This mode provides an optionality where users do not want to worry about managing multiple subnets, especially when using smaller clusters. Besides, let’s highlight some additional benefits unlocked by this feature. Improved Network Debugging Capabilities through Advanced Container Networking Services By upgrading to Azure CNI Powered by Cilium with Node Subnet, Advanced Container Networking Services opens the possibility of using eBPF tools to gather request metrics at the node and pod level. Advanced Observability tools provide a managed Grafana dashboard to inspect these metrics for a streamlined incident response experience. Advanced Network Policies Network policies for Legacy CNI present a challenge because policies on IP-based filtering require constant updating in a Kubernetes cluster where pod IP addresses frequently change. Enabling the Cilium data plane offers an efficient and scalable approach to managing network policies. Create an Azure CNI Powered by Cilium cluster with node subnet as the IP Address Management (IPAM) networking model. This is the default option when done with a `--network-plugin azure` flag. az aks create --name <clusterName> --resource-group <resourceGroupName> --location <location> --network-plugin azure --network-dataplane cilium --generate-ssh-keys A flat network can lead to less efficient use of IP addresses. Careful planning through the List Usage command of a given VNet helps to see current usage of the subnet space. AKS creates a VNet and subnet automatically from cluster creation. Note the resource group for this VNet is generated based on the resource group for the cluster, the cluster name, and location. From the Portal under Settings > Networking for the AKS cluster, we can see the names of the resources created automatically. az rest --method get \ --url https://management.azure.com/subscriptions/{subscription-id} /resourceGroups/MC_acn-pm_node-subnet-test_westus2/providers/Microsoft.Network/virtualNetworks/aks-vnet-34761072/usages?api-version=2024-05-01 { "value": [ { "currentValue": 87, "id": "/subscriptions/9b8218f9-902a-4d20-a65c-e98acec5362f/resourceGroups/MC_acn-pm_node-subnet-test_westus2/providers/Microsoft.Network/virtualNetworks/aks-vnet-34761072/subnets/aks-subnet", "isAdjustable": false, "limit": 65531, "name": { "localizedValue": "Subnet size and usage", "value": "SubnetSpace" }, "unit": "Count" } ] } To better understand this utilization, click the link of the Virtual network then access the list of Connected Devices. The view also shows which IPs are utilized on a given node. There are a total of 87 devices consistent with the previous command line output of subnet usage. Since the default creates three nodes with a max pod count of 30 per node (configurable up to 250), IP exhaustion is not a concern although careful planning is required for larger clusters. Next, we will enable Advanced Container Networking Services (ACNS) on this cluster. az aks update --resource-group <resourceGroupName> --name <clusterName> --enable-acns Create a default deny Cilium Network policy. The namespace is `default`, and we will use `app: server` as the label in this example. kubectl apply -f - <<EOF apiVersion: cilium.io/v2 kind: CiliumNetworkPolicy metadata: name: default-deny namespace: default spec: endpointSelector: matchLabels: app: server ingress: - {} egress: - {} EOF The empty brackets under ingress and egress represent all traffic. Next, we will use `agnhost`, a network connectivity utility used in Kubernetes upstream testing that can help set up a client/server scenario. kubectl run server --image=k8s.gcr.io/e2e-test-images/agnhost:2.41 --labels="app=server" --port=80 --command -- /agnhost serve-hostname --tcp --http=false --port "80" Get the server address IP: kubectl get pod server -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES server 1/1 Running 0 9m 10.224.0.57 aks-nodepool1-20832547-vmss000002 <none> <none> Create a client that will use the agnhost utility to test the network policy. Open a new terminal window as this will also open a new shell. kubectl run -it client --image=k8s.gcr.io/e2e-test-images/agnhost:2.41 --command -- bash Test connectivity to the server from client. Timeout is expected since the network policy is default deny for all traffic in the default namespace. Your pod IP may be different from the example. bash-5.0# ./agnhost connect 10.224.0.57:80 --timeout=3s --protocol=tcp –verbose TIMEOUT Remove the network policy. In practice, additional policies would be added to retain the default deny policy while allowing applications that satisfy the conditions to allow connectivity. kubectl delete cnp default-deny From a shell with the client pod, verify the connection is now allowed. If successful, there is simply no output. kubectl attach client -c client -i -t bash-5.0# ./agnhost connect 10.224.0.57:80 --timeout=3s --protocol=tcp Connectivity between server and client is restored. Additional tools such as Hubble UI for debugging can be found in Container Network Observability - Advanced Container Networking Services (ACNS) for Azure Kubernetes Service (AKS) - Azure Kubernetes Service | Microsoft Learn. Conclusion Building a seamless migration path is critical to continued growth and adoption of ACPC. The goal is to provide a best-in-class experience by providing an upgrade path to enable the Cilium data plane to enable high-performance networking across various IP addressing modes. This allows for flexibility to fit your IP address plans to build varied workload types using AKS networking. Keep an eye out on the AKS public roadmap for more developments in the near future. Resources Learn more about Azure CNI Powered by Cilium. Learn more about IP address planning. Visit Azure CNI Powered by Cilium benchmarking to see performance benchmarks using an eBPF dataplane. Visit to learn more about Advanced Container Networking Services.
