Azure Kubernetes Service (AKS) Clusters are amazing - all the power of Kubernetes (K8s) without the hassle of a full tin-based installation. Each service should own its own private data in a separate logical storage, to avoid hidden dependencies among services. For non-production workloads that include Azure SQL Database or Azure App Service as part of the AKS workload architecture, evaluate if you are eligible to use Azure Dev/Test subscriptions to receive service discounts. Use the Azure pricing calculator to estimate costs. Set pod disruption budgets. For more information, see Add secret management. Helm. Microservices are typically stateless and write state to external data stores, such as Azure SQL Database or Cosmos DB. Azure AD integration also simplifies security for outside-in access. The base layers include the OS image and application framework images, such as ASP.NET Core or Node.js. Define resource constraints for containers, so that a single container cannot overwhelm the cluster resources (memory and CPU). For an example about how Azure Application Gateway accesses TLS certificates for the ingress flow, see the Ingress traffic flow section. Where you can opt to purchase an Uptime SLA (roughly a bit less than 70 Euro per month per cluster). Architecture The architecture consists of the following components. Also, expect additional network latency in node communication between zones or regions. There are no costs associated for AKS in deployment, management, and operations of the Kubernetes cluster. Tags give the ability to track the total of expenses and map any cost to a specific resource or team. The responses will use gzip encoding if the client accepts. A service has a label selector that matches a set of (zero or more) pods. Use load testing to fine-tune these values. When the pod needs a secret, the driver connects with the specified store, retrieves secret on a volume, and mounts that volume in the cluster. For information about a performance tuning scenario using AKS, see Performance tuning scenario: Distributed business transactions. Use Container Registry to store private Docker images, which are deployed to the cluster. This architecture has several layers of security to secure all types of traffic. Other popular options include Azure DevOps Services and Jenkins. For specific recommendations and best practices, see CI/CD for microservices on Kubernetes. This role does not give any particular permissions on Kubernetes resources inside the cluster — it just allows a user to connect to the API server. Container image reference Consider these points. With AKS, Azure manages some core Kubernetes services. There’s also an option of using Azure RBAC roles instead of the Kubernetes built-in roles. Also, if the cluster is shared between teams, build chargeback reports per consumer to identify metered costs for shared cloud services. There are Ingress controllers for Nginx, HAProxy, Traefik, and Azure Application Gateway, among others. An implementation of this architecture is available on GitHub: Azure Kubernetes Service (AKS) Secure Baseline Reference Implementation. Only CPU utilization is provided out of the box. Cluster and node availability When you define your RBAC policies (both Kubernetes and Azure), think about the roles in your organization: It's a good practice to scope Kubernetes RBAC permissions by namespace, using Roles and RoleBindings, rather than ClusterRoles and ClusterRoleBindings. You can implement end-to-end TLS traffic all at every hop the way through to the workload pod. If an unresponsive pod is detected, Kubernetes restarts the pod. The Ingress resource can be fulfilled by different technologies. Keeping your node images in sync with the latest weekly release will minimize these occasional reboot requests while maintaining an enhanced security posture. With managed identities, Azure AD manages and performs the authentication and timely rotation of secrets for you. Communication between pods. Use a validating admission webhook in Kubernetes to ensure that pods can only pull images from the trusted registry. Network topology Logs from those services should only be enabled per request from customer support. Add secret management, Scalability You can also use third-party CI/CD solutions such as Jenkins. For zero-trust control and the ability to inspect traffic, all egress traffic from the cluster moves through Azure Firewall. In a microservices architecture, services should not share data storage. Also, CNI allows for more scaled pods than kubenet. AKS is an Azure service that deploys a managed Kubernetes cluster. Think from the cluster's perspective when you're making security choices: Outside-in access. This reference architecture provides an Azure Resource Manager template for provisioning the cloud resources, and its dependencies. The pod can then get the secret from the volume file system. Creating an AKS cluster is easy and there are more … Factor in the addresses that are required for communication with other Azure services over Private Link. An effective way to manage an AKS cluster is by enforcing governance through policies. Multizone support not only applies to node pools, but the control plane as well. Organizations often operate with regional hub-spoke topologies. Measure the impact of this architectural decision on your workload. The certificates are stored in Azure Key Vault and mounted into the cluster using the Container Storage Interface (CSI) driver. Other resources of the infrastructure, such as Azure Firewall and Application Gateway are deployed to the same region also with multizone support. In this architecture, we've chosen GitHub Actions for managing the workflow and deployment. Readiness probe determines if the pod is ready to receive requests/traffic. Another way is to watch for pending pods over time. To learn about monitoring this architecture, see, To learn how we measured the performance of this application, see. That way, you don't need to store any passwords or connection strings. In this reference implementation, the cluster only pulls images from ACR that is deployed as part of the architecture. The ingress controller receives the encrypted traffic through the load balancer. For example, in this architecture, Azure Container Registry is enabled for geo-replication. An installation might require the node VMs to be rebooted. These new images are not automatically applied. This way, Kubernetes services run on dedicated nodes and don’t compete with your workload. Also, when services manage their own data stores, they can use the right data store for their particular requirements. About Azure Kubernetes Service (AKS) To grant access, the cluster administrator creates RoleBindings that refer to Azure AD users or groups. You will review the design decisions made for … A side-effect of autoscaling is that pods may be created or evicted more frequently, as scale-out and scale-in events happen. To meet the minimum level of availability for workloads, multiple nodes in a node pool are needed. Act on recommendations provided by Azure Advisor. The underlying virtual machine scale set provides the same hardware configuration across zones. There are two ways to manage access through Azure Active Directory (Azure AD): service principals or managed identities for Azure resources. AKS is a managed service that you can use to configure and manage your … It's done during pod creation and the volume stores both public and the private keys. The container doesn't crash, but it has stopped serving any requests. It’s highly recommended that deployments specify pod resource requirements. That way, the front end can't starve the backend services for resources or vice-versa. To enable monitoring, we need to create a log analytics workspace resource. Azure policies are assigned to specific scopes. Integrate the recovery strategy, such as replicating to another region, as part of the DevOps pipeline to meet your Service Level Objectives (SLO). For information about TLS encryption for inbound traffic, see Ingress traffic flow. Create budgets to stay within the cost constraints identified by the organization. You need a separate cluster autoscaler for each user node pool. Then use a combination of performance metrics and manual scaling to locate bottlenecks and understand the application’s response to scaling. Do you have requirements that are not covered by the built-in policies? Azure offers the Azure Pipeline as an individual Service. Microservices typically communicate through well-defined APIs and are discoverable through some form of service discovery. AKS updates nodes regularly to make sure the underlying virtual machines are up to date on security features and other system patches. For cluster scaling, one way is to get notified when the Kubernetes scheduler fails. Without this layer of security, the flow might communicate with a malicious third-party service that could exfiltrate sensitive company data. Ensure the production policies are also validated against your pre-production environment. If your workload supports it, scale your user node pools to 0 nodes when there is no expectation for them to be running. The recommended SKU is DS2_v2. Upgrading to the latest version of Kubernetes is critical because new versions are released frequently. The application or service has a Service Principal created for it in Azure AD, and authenticates using OAuth 2.0 tokens. Mount a persistent volume using Azure Disks or Azure Files. Only pods that started successfully and are healthy receive traffic. NAT isn't needed for routing that traffic. To work together, they need to be deployed as the Ingress controller inside the cluster. For example, if a pod has a dependency on a database, the probe might check the database connection. For example, the workload stores files in the Azure Storage. In general, CNI is recommended. This allows you save cost and provision load testing environment only when needed. An ingress exposes HTTP(S) routes to services inside the cluster. Kubernetes has some built-in roles such as cluster-admin, edit, view, and so on. In these rare cases, create a custom Azure Policy definition that applies your custom OPA Gatekeeper policies. For more information, see Azure RBAC roles. Currently, not all Azure services support authentication using managed identities. You can implement that choice using user-defined routes (UDRs). Use the built-in feature of those services to access secrets. A complete scaling solution must have ways to scale both pod replicas and the node count in the cluster. With increasing demand, Kubernetes can scale out by adding more pods to existing nodes, through horizontal pod autoscaling (HPA). To estimate the limits, test and establish a baseline. Quality gates are enforced at each stage. The hub and spoke(s) are deployed in separate virtual networks connected through peering. Because Traefik does TLS termination, communication with the backend services is over HTTP. To indicate that a pod is healthy but not ready to receive traffic, define a readiness probe. For more information, see Specify a taint, label, or tag for a node pool. To learn more about storage options, see Storage options for applications in Azure Kubernetes Service (AKS). Flagger is a popular open-source solution to help solve for your advanced deployment scenarios. If a container crashes, Kubernetes kills the pod and schedules a replacement. Also have a good understanding of the meters that are used to calculate usage of each resource. A reverse proxy server is a potential bottleneck or single point of failure, so always deploy at least two replicas for high availability. This subnet is a placeholder for a VPN or ExpressRoute gateway. Examples of those resources include the build agent pool in a DevOps pipeline, a Bastion subnet, and node pools themselves. For information about generating and configuring Let's Encrypt certificates, see Create an ingress controller with a static public IP address in Azure Kubernetes Service (AKS). A container image is built up from layers. Azure AD will authenticate the user’s identity against the Azure Resource Manager RBAC roles that are allowed to get cluster credentials. Another cross-platform option is Azure PowerShell. The Ingress controller also has access to the Kubernetes API, so it can make intelligent decisions about routing and load balancing. Configure advanced networking in Azure Kubernetes Service (AKS), Designing microservices: Data considerations, Overview of load-balancing options in Azure, Create an HTTPS ingress controller and use your own TLS certificates on Azure Kubernetes Service (AKS), Create an ingress controller with a static public IP address in Azure Kubernetes Service (AKS), Rotate certificates in Azure Kubernetes Service (AKS), Integrate Azure Active Directory with Azure Kubernetes Service, Service principals with Azure Kubernetes Service, Azure services that support Azure AD authentication, HashiCorp Vault speaks Azure Active Directory, Container Monitoring solution in Azure Monitor, Microsoft Azure Well-Architected Framework, Monitoring a microservices architecture in Azure Kubernetes Service (AKS), Performance tuning scenario: Distributed business transactions. In this architecture, Azure Load Balancer is used. Instead, Use an external service such as Azure SQL Database or Cosmos DB, or. Consider following the workload isolation criteria to structure your ARM template, a workload is typically defined as an arbitrary unit of functionality; you could, for exmaple, have a separate template for the cluster and then other for the dependant services. 1. For a list, see Azure services that support Azure AD authentication. Azure Policy provides two built-in initiatives: basic and restricted. Minimizes direct exposure of Azure resources to the public internet. Egress traffic. That choice may result in more subnets that are smaller in size. It has the capability to create alerts that trigger Automation Runbooks, Azure Functions, and others. That approach isn't necessary or recommended for most situations. Liveness probe: Tells Kubernetes whether a pod should be removed and a new instance started. Network flow, in this context, can be categorized as: Ingress traffic. Start with a basic workload that contains the fundamental components and build on it. It's recommended that still apply policies in Audit mode so that you are aware of those instances. Regular upkeep of your cluster such as timely updates is crucial for reliability. This article includes recommendations for networking, security, identity, management, and monitoring of the cluster based on an organization’s business requirements. That size is sufficient to meet the expected load of the system pods. Apply policies at the namespace level, including RBAC and security policies. Once this is configured, a user who wants to access the Kubernetes API (for example, through kubectl) must sign in using their Azure AD credentials. Cluster. For example, creating pods and listing pods are actions that can be authorized (or denied) to a user through RBAC. By default, when you create a new object, it goes into the default namespace. Hub and spoke architecturesare commonly used to deploy networks in Azure. It allows for a way to apply governance and control the blast radius. A natural choice for workloads that span multiple subscriptions. To deploy the reference implementation for this architecture, follow the steps in the GitHub repo. If you are using a public image, consider importing it into your container registry that aligns with your SLO. Hub-spoke network topologies can be expanded in the future and provide workload isolation. Monitor your container infrastructure for both active threats and potential security risks: Here are some considerations. Geo-replication is enabled for Azure Container Registry. In many of these deployments, DNS settings in the spoke VNets are configured to reference a central DNS forwarder to allow for on-premises and Azure-based DNS resolution. The Azure Monitor for containers feature is the recommended tool for monitoring and logging because you can view events in real time. When thinking about probes, it's useful to recall how a service works in Kubernetes. The HorizontalPodAutoscaler definition specifies target values for those metrics. Azure Kubernetes Service (AKS) Azure Kubernetes Service (AKS) is a free container service that simplifies the deployment, management, and operations of Kubernetes as a fully managed … KubeControllerManager to have observability into pod scheduler. For example, there is a policy in place to make sure images are only pulled from the deployed ACR. In Kubernetes, the Ingress controller might implement the API gateway pattern. Logging on the ClusterAutoscaler to gain observability into the scaling operations. From a pod or node in the cluster to an external service. Note that AKS does not require Azure Container Registry. Traffic sent to the service's IP address is load balanced to the pods. However, it's a good security practice to create the service principal first and assign the minimal RBAC permissions to it. See Azure Load Balancer Pricing for more information. For more information, see Azure Kubernetes Service (AKS) node image upgrade the AKS Release Notes. This reference architecture only uses Azure Pipelines. For more information, see the secrets-store-csi-driver-provider-azure project on GitHub. If you are hosting containers on a VM, use Azure Defender for servers or a 3rd party capability. If you need to store state, persisting it outside the cluster is recommended. Updates must be deployed safely and quickly and rolled back in case there are issues. This article assumes basic knowledge of Kubernetes. AKS provides built-in self-healing of infrastructure nodes using Node Auto-Repair. It receives traffic from Azure Application Gateway and that communication is over TLS. Also, if your workload is composed of multiple applications deployed to the cluster, communication between those applications would fall into this category. It shows third-party products integration with Azure services. You should load test your services to derive these numbers. This architecture deploys Azure Load Balancer because it can distribute non-web traffic across zones. There are other ways to optimize: Enable the cluster autoscaler to detect and remove underutilized nodes in the node pool. Also, traffic between the cluster and the service isn't exposed to public internet. For example, you might allow the controller to only interact with the pods that run a specific workload. For more information, see. This architecture is designed for a single workload. Relying just on node image upgrades will ensure AKS compatibility and weekly security patching. The changes are then pushed to a git server. Cost management and reporting. When you create an AKS cluster… Offload functionality from the backend services, such as SSL termination, authentication, IP restrictions, or client rate limiting (throttling). 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