Connecting-Securely-to-AKS-Private-Cluster

🔐 Securely Connecting to an AKS Private Cluster

Overview

This guide outlines various methods for securely accessing an Azure Kubernetes Service (AKS) private cluster, particularly when the cluster is configured with a private endpoint and resides within a virtual network (VNet).

Key Components

• AKS Private Cluster: A Kubernetes cluster with a public FQDN but restricted to private network access.
• Cloud Shell in Azure Virtual Network: Enables Cloud Shell to run inside a user-defined VNet for secure resource access.
• Azure Container Instance (ACI): Hosts the Cloud Shell session when deployed into a VNet, managed by Microsoft.
• Azure Relay: Allows two endpoints that aren’t directly reachable to communicate. It’s used to allow the administrator’s browser to communicate with the container in the private network.
• Azure File Share: Provides persistent storage for Cloud Shell containers hosted in Azure Container Instances (ACI), enabling data sharing across Cloud Shell sessions (users).

📘 Scenario: Accessing a Private AKS Cluster via Private Connectivity

You have an AKS private cluster with a public FQDN, but its API server is only accessible through a private endpoint (private IP) bound to a network interface (NIC) within your VNet. To interact with this cluster, you must establish connectivity to the VNet hosting the endpoint.

✅ Access Options

1. Run Command via Azure portal in AKS Resource
Access to your kubernetes resources on your AKS resource, click on Run command to interact with AKS cluster.

2. Azure Bastion via Portal with Jump box
Use Azure Bastion to connect to a jump box VM through the Azure Portal, eliminating the need for public IPs.

3. Cloud Shell in Azure Virtual Network
Launch Cloud Shell inside the VNet and use kubectl commands to interact with the AKS cluster securely.

4. On-Premises Network via VPN or ExpressRoute
Establish a secure connection to the Azure jumpbox’s private IP from your corporate network using VPN or ExpressRoute, thereby enabling secure access to the AKS private endpoint.

5. AKS Invoke via Azure CLI or Powershell
You can execute the az aks command invoke using the -c parameter from Azure Cloud Shell or the Azure CLI/PowerShell on your local machine, provided you’re authenticated to your subscription. Note that this method supports only one command execution at a time.

6. Bastion-AKS Direct Integration (Preview)
Azure Bastion now supports direct integration with AKS (currently in preview). For a detailed walkthrough, refer to Richard Hooper (@PixelRobots)’s excellent explanation.

Architecture Diagram

The diagram below presents the various access methods and infrastructure components involved in deploying and connecting to an Azure Kubernetes Service (AKS) private cluster.

🚧 Deployment Guide

This project demonstrates how to deploy Azure Cloud Shell with VNet integration to securely connect to a private AKS (Azure Kubernetes Service) cluster.

🔴 Cloud Shell with VNet integration requires a network profile, file share, and Azure Relay namespace. See deployment.md for detailed setup instructions.

🔧 Key Objectives

• Enable Cloud Shell access to resources within a private virtual network.
• Establish secure connectivity to a private AKS cluster using VNet peering and private endpoints.
• Simplify developer access to Kubernetes management tools without exposing the cluster to the public internet.

🧰 Resources

• Microsoft Cloud Shell in Virtual Network Overview
• Microsoft Cloud Shell Deployment ARM Template

✅ Conclusion

This deployment showcases a secure and flexible method for accessing a private AKS cluster using Azure Cloud Shell with VNet integration. By placing Cloud Shell within a virtual network, you eliminate public exposure of the Kubernetes API and ensure that all management traffic flows through trusted, internal paths.

Beyond AKS, this setup also enables secure access to other private Azure resources such as storage accounts, databases, and virtual machines; making Cloud Shell a powerful tool for managing infrastructure in isolated environments.

This approach aligns with best practices for enterprise-grade security, operational efficiency, and network segmentation in Azure.

🧠 FAQ Reflection

As I worked through this architecture, several questions naturally came to mind, things I wanted to understand better or clarify for future reference. I’ve documented the answers I found in the FAQ section . These are based on my own exploration and experience, but I’d love to hear your thoughts too. Do these answers make sense to you? Are there other perspectives, questions, or ideas you’d like to add? Feel free to contribute or open a discussion/collaboration helps us all learn more effectively.