Sometmes it would be necessery to identify which priority classes are used in each pod in a kubernetes environment, specially to plan and reorganize priorities in apps deployed. Let's look at a query to view pods with priority classes using kubectl.
Below command will get all pods in all namespaces with their priority classes name and priority value. The highest priority number value is the highet priority.
We have discussed "Windows AKS Scaled Jobs Handle Graceful Termination for dotnet App using IHostedService When Preemption" previously. However, for Linux scaled jobs we have to handle the graceful termination, using a bash script intead of a PowerShell script.
We can create a script with bash as shown below.
We have discussed "Gracefully Shut Down dotnet 8 IHostedService App - Deployed as a Windows Container in AKS - While Scale In or Pod Deallocations" previously. The approach works fine for pods deployed as a deployment in kubernetes. Similary to the deployment pods, scaled job pod can be terminated abruptly due to preemption in kubernetes, if a high priority pod is scheduled. One way to reolve abrupt termination of scaled job pod due to preemption, would be to assign all scaled jobs to highest possible priority. However, setting highest prority to all scaled jobs is not a good solution, as the job may not require highest priority and job should be able to scheduled after other high priority app pods. Let's look at a better solution that can be implented with pre stop hook for scaled jobs running with base docker image Windows server core 2022.
The pods deployed to AKS gets terminated due to reschduling, low priority evictions as well as during scaled in. We can add a termination grase period and pre stop sleep time as shown below in Linux and Windows containers to allow, sufficient time to ingress services to get updated about terminating pods. However, Windows nanoserver does not support PowerShell. Therefore, we need to use a specific mechanism to pre stop hook for nanoserver images. For nanoserver images shutdown signal is correctly get sent to the dotnet app. So we can just setup a sllep time for pre stop hook as necessary.
