Running PowerShell based scheduled task in windows container on AKS

Aim

To schedule a task inside Windows container and ensure its triggering

How to run - Docker

• Open the commands.ps1 and execute
• It builds the image and run interactively.
• It already has commands to run once the container starts
• If all working good the c:\stask.log file in container will be appended with date time every minute

How to run - Kubernetes

• Follow the instructions in the "Run inside AKS" of commands.ps1
  • Mainly tag and push the image to your registry
  • After replacing your registry execute kubectl apply -f pod.yaml
    • Note that this will hold the container running only for 10 mins.
  • If the image registry is not replaced it will be taking image from my dockerhub registry
  • exec into the container and ensure the c:\stask.log file is getting updated

Environment

• Base image - mcr.microsoft.com/windows/servercore:ltsc2019
• Scheduled task technology - PowerShell

Design

Below are some points about how it is structured

• The tasks.xml file has the task definition
• Task logic
  • The powershell command appends the Get-Date to c:\stask.log file
• Dockerfile gets the task.xml file and create task using schtasks.exe
• For testing container can be started in interactive mode (with -it switch)
• Dockerfile can have entrypoint when using this for production.

Interesting

• The Dockerfile don't have any EntryPoint to hold the container when running inside AKS. So pod.yaml needs to hold it for sometime with the help of args. Ideally timeout 600 is enough but it will throw "ERROR: Input redirection is not supported, exiting the process immediately". To workaround that the pod.yaml file uses start /wait with timeout

On the web

• Azure @ Enterprise - Scheduling task inside Windows container in Kubernetes