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![Resource reservations
https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#nodes-and-node-pools
AKS uses node resources to orchestrate the node
Using AKS add-ons will consume additional node resources such as Container Insights (OMS)
Demo : check this command -> kubectl describe node [NODE_NAME] Admin](https://image.slidesharecdn.com/aks-core-componets-221130130726-055b5409/85/AKS-components-6-320.jpg)
AKS components
- 1. Azure Kubernetes Service (AKS) PROVISION IN G W ITH TER R AFOR M OC T 2022 Core Concept
- 2.
- 3. Control plane • AKSControl plane • Kubernetes Cluster Control Plane contains the services for orchestration the cluster e.g., for api server, scheduler, etc. • It’s a single tenant • With a dedicated API Server • Interaction with control plane through Kubernetes API such as kubectl • AKS Control plane types • Single node (the common one for dev/test) • Multiple nodes (the common one for prod + high availability (HA)) https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads
- 4. Node pool • AKSmust have at least one node pool, which is a system node pool. • System node pool is for the control plane or core services. • System node pool is Linux-based. • System node pool must have at least one node. • For the workloads, the user node pool must be used. • User node pool can be Windows-based or Linux-based OS. • A user node pool contains only the nodes of the same OS & size. • User node pool can have even zero node. (for the cost optimization purposes)
- 5. Kubernetes node components https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#nodes-and-node-pools •Kubelet -> The Kubernetes agent that processes the orchestration requests from the control plane along with scheduling and running the requested containers • Kube-proxy -> Handles virtual networking on each node. The proxy routes network traffic and manages IP addressing for services and pods • Container runtime -> Allows containerized applications to run and interact with additional resources, such as the virtual network and storage
- 6. Resource reservations https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#nodes-and-node-pools AKS usesnode resources to orchestrate the node Using AKS add-ons will consume additional node resources such as Container Insights (OMS) Demo : check this command -> kubectl describe node [NODE_NAME] Admin
- 7. Resource reservations https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads Type ofreserved resources - CPU is reserved based on kube-reserved (millicore) for each CPU on host - Memory - Kubelet daemon - Kubelet daemon functionality - For Windows nodes, some additional memory reservation is required for system process
- 8. Node selectors Node selectors-> in multiple node pools we may need to specify the node pool for the Kubernetes Scheduler e.g., ingress controllers shouldn't run on Windows Server nodes https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#node-selectors Watch in Terraform Demo: look at win and ubuntu node pool
- 9. Pods • Pods typicallyhave a 1:1 mapping with a container. • In advanced scenarios, a pod may contain multiple containers. • Multi-container pods are scheduled together on the same node, and allow containers to share related resources https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#pods Watch in Terraform Demo
- 10. StatefulSets and DaemonSets Deploymentcontroller • StatefulSets -> maintain the state of applications beyond an individual pod lifecycle • DaemonSets -> ensure a running instance on each node, early in the Kubernetes bootstrap process If using the Virtual Nodes add-on, DaemonSets will not create pods on the virtual node https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads
- 11. Namespaces Namespaces • Default ->pods and deployments are created by default when none is provided. In smaller environments, you can deploy applications directly into the default namespace without creating additional logical separations • kube-system -> core resources exist, such as network features like DNS and proxy, or the Kubernetes dashboard. You typically don't deploy your own applications into this namespace • kube-public -> Typically not used, but can be used for resources to be visible across the whole cluster, and can be viewed by any user https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads Watch in Terraform Demo
- 12. AKS / Kuberneteswording Kubernetes manifest file defines a cluster's desired state, such as which container images to run internal service which is accessible only internal / inside the cluster e.g., Redis instance external service Which is accessible from public internet e.g., for frontend
- 13. Next topic AKS Securityconcept for applications and clusters
Editor's Notes
- #6 Talk about: Based on the scenario select an appropriate vm size, Disk type SSD / HDD, Scale out number, consider the appropriate ip space for the network VM images can be Ubuntu Linux or windows server 2019 You can use the Azure Reservation as well
- #7 Talk about: To maintain node performance and functionality, AKS reserves resources on each node. As a node grows larger in resources, the resource reservation grows due to a higher need for management of user-deployed pods
- #8 Talk about: To maintain node performance and functionality, AKS reserves resources on each node. As a node grows larger in resources, the resource reservation grows due to a higher need for management of user-deployed pods
- #10 Talk about When you create a pod, you can define resource requests to request a certain amount of CPU or memory resources You can also specify maximum resource limits to prevent a pod from consuming too much compute resource from the underlying node Best practice is to include resource limits for all pods to help the Kubernetes Scheduler identify necessary, permitted resources
- #11 Talk about
- #12 Talk about