Prevent power down on change

prevent_powerdown.py

import json

def handler(context, inputs):
    # We only care about updates
    if inputs["eventType"] != "UPDATE_DEPLOYMENT":
        return inputs
    result = context.request("/blueprint/api/blueprint-requests/%s/resources-plan?expand=true" % inputs["id"], "GET", "")
    if result["status"] != 200:
       raise Exception(result["content"])
    envelope = json.loads(result["content"])
    print(envelope)
    for resource in envelope["resources"]:
        # We only care about machines
        if not resource["resourceType"].endswith(".Machine"):
            continue
        new_props = resource["newProperties"]
        old_props = resource["oldProperties"]
        print("Old cpu: %d, new cpu %d" % (old_props["cpuCount"], new_props["cpuCount"]))
        
        # If the machine is already powered off, we're fine
        if new_props["powerState"] == "OFF":
            continue
 
        # If the VM doesn't support hot add AND we're changing the number of CPUs, we need to stop this 
        # deployment, since it would power down the VM.
        if new_props.get("__cpuHotAddEnabled", "false") != "true" and old_props.get("cpuCount", -1) != new_props.get("cpuCount", -1):
            raise Exception("Changing number of CPUs on a powered on machine isn't allowed")
            
        # If the VM doesn't support hot add AND we're changing the amount of memory, we need to stop this 
        # deployment, since it would power down the VM.
        if new_props.get("__memoryHotAddEnabled", "false") != "true" and old_props.get("totalMemoryMB", -1) != new_props.get("totalMemoryMB", -1):
            raise Exception("Changing the amound of memory on a powered on machine isn't allowed")
    return inputs