Azure Kubernetes Service (AKS)

Introduction to Azure Kubernetes Service

Azure Kubernetes Service (AKS) simplifies deploying, managing, and scaling containerized applications by using Kubernetes on Azure. AKS provides a managed Kubernetes experience, offloading the operational overhead of a control plane to Azure. You manage the worker nodes, and Azure manages the Kubernetes control plane for you.

This documentation will guide you through understanding AKS, getting started with cluster creation, deploying applications, and leveraging advanced features.

Getting Started with AKS

Prerequisites

Before you can create an AKS cluster, ensure you have the following:

• An Azure subscription.
• The Azure CLI installed and configured, or use Azure Cloud Shell.
• A resource group to contain your AKS cluster.

Creating an AKS Cluster

You can create an AKS cluster using the Azure CLI. Here's a basic example:

az group create --name myResourceGroup --location eastus
az aks create --resource-group myResourceGroup --name myAKSCluster --node-count 1 --enable-addons monitoring --generate-ssh-keys
                

After the cluster is created, configure the Kubernetes command-line client to connect to your cluster:

az aks get-credentials --resource-group myResourceGroup --name myAKSCluster
                

Verify the connection:

kubectl get nodes
                

Kubernetes Core Concepts on AKS

Pods

A Pod is the smallest deployable unit in Kubernetes, representing a single instance of a running process in your cluster. A Pod can contain one or more containers that share resources and network namespaces.

Deployments

Deployments provide declarative updates for Pods and ReplicaSets. You define the desired state, and the Deployment Controller changes the actual state to the desired state at a controlled rate.

Services

Services provide a stable IP address and DNS name for a set of Pods. They enable network access to your applications and act as a load balancer. Common service types include ClusterIP, NodePort, and LoadBalancer.

Namespaces

Namespaces provide a mechanism for isolating groups of resources within a single cluster. They are useful for managing multiple teams or projects within the same cluster.

Managing AKS Clusters

Upgrading AKS

Keeping your AKS cluster up-to-date is crucial for security and feature access. You can upgrade the Kubernetes version of your cluster and its node images.

# List available upgrade versions
az aks get-upgrades --resource-group myResourceGroup --name myAKSCluster

# Perform an upgrade
az aks upgrade --resource-group myResourceGroup --name myAKSCluster --kubernetes-version 
                

Scaling AKS

You can scale the number of nodes in your node pool, or use the Cluster Autoscaler to automatically adjust the node count based on resource requests.

# Manual scaling
az aks scale --resource-group myResourceGroup --name myAKSCluster --node-count 3

# Enable Cluster Autoscaler (during creation or update)
az aks update --resource-group myResourceGroup --name myAKSCluster --enable-cluster-autoscaler --min-count 1 --max-count 5
                

Monitoring and Logging

AKS integrates with Azure Monitor for container insights, providing performance metrics and logs. You can also configure dedicated logging solutions.

Deploying Applications to AKS

Deploying a Simple Application

You can deploy applications using Kubernetes manifest files (YAML). Here's an example of deploying a simple Nginx application:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: LoadBalancer
                

Save this content to a file named nginx-app.yaml and apply it using kubectl apply -f nginx-app.yaml.

Helm Charts

Helm is a package manager for Kubernetes that simplifies the deployment and management of complex applications. AKS supports Helm, allowing you to easily deploy applications from Helm repositories.

AKS Networking

Network Policies

Network Policies are Kubernetes resources that control the traffic flow between Pods. You can use them to enforce network segmentation and security best practices.

Ingress Controllers

Ingress controllers manage external access to services in a cluster, typically HTTP and HTTPS. AKS offers an integrated Azure Application Gateway Ingress Controller (AGIC).

Virtual Networks

AKS clusters can be integrated with Azure Virtual Networks (VNet), allowing for advanced networking configurations and seamless integration with other Azure services.

AKS Security

Azure Active Directory Integration

Integrate AKS with Azure Active Directory (Azure AD) for robust authentication and authorization, enabling role-based access control for your cluster resources.

Secrets Management

Securely store and manage sensitive information like passwords and API keys using Kubernetes Secrets, and consider integrating with Azure Key Vault for enhanced security.

Image Security

Scan container images for vulnerabilities using tools like Aqua Security or Twistlock, and implement policies to prevent the deployment of insecure images.

Monitoring and Logging in AKS

Azure Monitor for containers

Azure Monitor for containers provides performance monitoring and health analysis for your AKS cluster. It collects metrics and logs, offering valuable insights into your applications and infrastructure.

Log Analytics

Configure AKS to send logs to Azure Log Analytics for centralized logging and advanced querying capabilities. This is essential for troubleshooting and auditing.

Alerting

Set up alerts based on metrics and log data to proactively identify and respond to issues within your AKS cluster.

Scaling Your AKS Applications

Horizontal Pod Autoscaler (HPA)

HPA automatically scales the number of Pods in a Deployment or ReplicaSet based on observed CPU utilization or custom metrics.

Cluster Autoscaler

The Cluster Autoscaler automatically adjusts the size of your cluster by adding or removing nodes based on pending Pods. This ensures your applications have the resources they need without over-provisioning.

AKS Best Practices

• Secure your cluster: Use Azure AD integration, network policies, and regular upgrades.
• Optimize resource usage: Set resource requests and limits for your containers.
• Implement CI/CD: Automate your build, test, and deployment pipelines.
• Monitor and log: Utilize Azure Monitor for insights and troubleshooting.
• Regularly upgrade: Stay current with Kubernetes and AKS versions.
• Use Namespaces: Organize your resources logically.