AKS on Azure Stack HCI and Windows Server - April 2022 update
Published Apr 18 2022 04:44 PM 3,383 Views

Hello everyone,


The April update of AKS on Azure Stack HCI and Windows Server is now available! 


You may be asking yourself what happened to the March release - we decided to hold the March release because we found problems upgrading the host operating system.  We want every release to be better than previous one, so we chose to delay the release and support the newest platform updates.  As a general rule, we will continue to ship monthly.


Now, back to talking about the April update - this update is full of tools for scaling running AKS deployments such support for horizontal autoscaling and manual vertical scaling.  In addition to all of the scale tools, we also added several stability updates, Australia East Azure region support, and we cleaned up the list of URLs our service calls into.


As always, you can try AKS on AzureStack HCI or Windows Server any time by registering here. If you do not have the hardware handy to evaluate AKS on physical hardware you can use an Azure VM:  https://aka.ms/aks-hci-evalonazure.


Here are some of the changes you'll see in this update:


Automatic horizontal scaling for scaling up and down nodes in a cluster

To adjust to changing application demands, such as between the workday and evening or on a weekend, clusters often need a way to automatically scale up or down. The cluster autoscaler scales up when pods can't be scheduled on nodes because of resource constraints. The cluster autoscaler also decreases the number of nodes (scaled down) when there has been unused capacity for a period of time.


For this preview release, you can use PowerShell to enable the autoscaler and to manage automatic scaling of node pools in your target clusters.  It's important to be able to manage cluster autoscaler behavior so we also included startup parameters for triggers like time intervals between scale events and resource thresholds.  Read more about configuring your autoscaler with autoscaler profiles from the docs.


This is currently in preview.


Support for manual vertical scaling by changing the size of the VMs in a Kubernetes cluster

Sometimes scaling a cluster horizontally by adding additional nodes isn't enough to meet the demands from your app - you may find you need more CPU cores or memory. Without vertical node scaling, you would need to redeploy to a new node pool and move the app.


Starting in this release, AKS on Azure Stack HCI or Windows Server lets you change the virtual machine (VM) size (SKU) of the VMs in a given node pool.


This is currently in preview.


Reduced required URLs

As more of you are deploying AKS on AzureStack HCI or Windows Server in production environments, we're seeing more tightly controlled firewall and proxy configurations. I'm very happy to share that the April release, we have removed all insecure URLs and all URLs with wildcards to make sure you can control traffic related to the AKS service.  We're down to 17 required URLs!


Support for Australia East region

Not much to say here - we've rolled out Australia East support for those of you in or near Australia who would like to run from an Azure Datacenter near you.


Security and reliability improvements


  • New Mariner kernel version to address CVE-2022-0185.  Read more about the Mariner March 2022 Update.
  • Fixed a bug that caused network interface to disappear after node reboots.
  • Increased the cert refresh cycle for our internal certs to 90 days.  This makes it so you can go 90 days between updates rather than 60 before having to renew certs.
  • We updated the error message for "out of disk space" errors to include guidance about how much space is needed.
  • Sometimes Windows Admin Center would show that there is a PowerShell module update available even after it has been updated - now it displays the right update status.
  • Fix a bug that caused workload cluster upgrade to hang.
  • Fix a bug that didn't honor external IP allocation for services.




Documentation related to scale:


New troubleshooting docs were published:


Once you have downloaded and installed the AKS on Azure Stack HCI April Update – you can report any issues you encounter and track future feature work on our GitHub Project at  https://github.com/Azure/aks-hci.


We look forward to hearing from you all!




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‎Apr 18 2022 04:43 PM
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