Gracefully Shut Down dotnet 8 IHostedService App - Deployed as a Windows Container in AKS - While Scale In or Pod Deallocations

 Applications implemented with IHostedService in dotnet, deployed to Azure Kubernetes Services (AKS) as containers in pods get terminated when pod recheduling happens or scaling-in opertaions happen. However, unlike Linux containers, the Windows containers does not receive the signal (similar to SIGTERM or SIGINT) to graceful shutdown. Once the pre stop hook is done the container is immediatly killed disregarding the value set in the terminationgraceperiod. Since, the Windows container did not receive a message to start a graceful shut down, and it is killed abruptly, the in flight operations in the Windows app container are abandoned. Such abadoning of operations cause inconsitency in system data and cause system failures. Therefore, it is mandatory to implement a proper graceful shutdown for Windows containers as well. Let's explore the issue in detail and how to implement a proper solution to enable graceful Windows container shut down, for dotent apps implemented with IHostedService. The issue is happening in mcr.microsoft.com/dotnet/runtime:8.0-windowsservercore-ltsc2022 images and the solution is tested with the same.

Windows app pod scaled-in or pod rescedule 

Setting Up Alert for AKS Pod Restarts Using Log Analytics Workspace and Grafana

 Azure Kubernetes Services (AKS)  pod restarts can be obtained from the KubePodInventory of the connected log analytics workspace. This data can be depicted in a graph in grafana as described in the post "Pod Restart Counts Grafana Chart with Azure Monitor for AKS". Let's explore how to use same information to create an alert using Grafana to notify when pod restarts are happening in apps in a given kubernetes namespace. 

The expectation is to fire alerts from Grafana as shwon below. Note that the alerts can target to send emails, slack notficaition etc. which is not discussed in this post.

Using "grep" with "kubectl logs" to Filter Container/Pod Logs

 kubectl logs command helps us to inspect logs of pods in AKS/kubernetes and useful to diagnose issues. However, when there is too much logs it is harder to read through and find out errors easily. Further, filtering out logs for a given timestamp may be useful at times to identify the issues. In this post let's explore usage of grep with kubectl logs command to filter logs. 

Let's take first example to filter for a timestamp in keda operator pod logs. Here -i says to ignore case in logs.

kubectl logs keda-operator-79d756dd66-69gsc -n keda | grep -i '2025-03-04T07:20:24'

Setup Azure File Share Capacity Alert to Slack with Terraform

 Setting up an Azure File Share capacity alert is useful to know when you reach at least 80% of allocated quota for the file share. This will give the teams ample time to increase the allocation to avoid out of space issues. If we are using standard tier for storage account then we need to use one storage account for each file share, to get the correct alert. Sending the alert to slack channel is a useful way to get properly alerted to take action on time. Let's use an example learn how to setup alerts for multiple Azure file shares uing terraform.

Expectation is to get the alerts to slack channel as shown below.