This presentation is about the AKS components as listed below. - Control plane - Different types of control planes & OS types - Node pools - Node - Pod - Resource reservation - Node selectors - Namespaces - StatefulSets and DaemonSets - Terraform deployment and Azure Portal demonstration Youtube video for this slide: https://youtu.be/yOsrai6id9I GitHub repo for these slides: https://github.com/ParisaMousavi/enterprise-aks WordPress post: https://multi-cloud-solutions.com/2022/11/30/azure-kubernetes-service-aks-with-terraform-deployment/

1. Azure Kubernetes
Service (AKS)
PR OVISION IN G W ITH
TER R AFOR M
OC T 2022
Core Concept

2. Control plane
https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads

3. Control plane
• AKS Control 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
• AKS must 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 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

7. Resource reservations
https://learn.microsoft.com/en-us/azure/aks/concepts-clusters-workloads
Type of reserved 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 typically have 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
Deployment controller
• 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 / Kubernetes wording
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 Security concept for applications and
clusters