[Hack Update] Dev/023 advanced kubernetes

[Ryan Peters (ryanpeters-MSFT)]

This pull request modernizes the Advanced Kubernetes course content and Helm chart solution to align with recent Azure AKS and Kubernetes best practices. The main updates include switching from NGINX Ingress to managed application routing with Istio and Gateway API, updating Helm chart templates for compatibility and extensibility, and revising GitOps instructions to use Azure-managed Flux and Argo CD. The changes also include improvements to scaling guidance and general documentation clarity.

Kubernetes Application Routing and Helm Chart Modernization:

• Updated Challenge 2 (02-helm.md) to use Azure-managed application routing with Istio and Gateway API instead of NGINX Ingress, reflecting current AKS best practices. Instructions now cover creating Gateway and HTTPRoute resources, disabling the legacy Ingress, and configuring hostnames dynamically. [1] [2] [3] [4]
• Added a gateway.yaml template to the solution Helm chart and updated the NOTES.txt to provide user-friendly instructions for both Gateway API and legacy Ingress, including dynamic hostname and path handling. [1] [2]
• Improved Helm chart templates for extensibility: deployment now supports additional pod labels, security context, probes, resources, and volume configuration via values; HPA updated to autoscaling/v2 API and modern target specification; fixed minor template issues and clarified comments. [1] [2] [3] [4] [5] [6]

GitOps and Automation Updates:

• Overhauled the GitOps challenge (05-gitops.md) to provide parallel instructions for Azure-managed Flux v2 and Argo CD, with validation steps, troubleshooting, and optional Helm-in-Git workflows. The new guidance replaces legacy Flux bootstrap and manual steps with managed extension usage and best practices for both tools.

Scaling and Documentation Enhancements:

• Added guidance on choosing node scaling strategies, including Azure's managed Karpenter-based node auto-provisioning (NAP) and multi-SKU node pools, to the scaling challenge.

Dev Container and Environment:

• Introduced a .devcontainer.json for the Advanced Kubernetes module, pre-configured with necessary tools, features, and VS Code extensions for a streamlined student environment.