Hello Kumar,
You can use this method to alerted (as example let keep it when someone created an instance).
First, create a
Log based metric, to do, you need to go in the
stackdriver logging and in advanced filter mode, put the filter below and click on Top "CREAT METRIC" (keep it as counter), when you finish this metric will be listed under "
Logs-based metrics"
Filter: protoPayload.methodName="v1.compute.instances.insert"
Second, Go to
Stackdriver Monitoring and create an
Alert policy, click on "Add condition" then look for the metric name that you created above (normally it should have this format :logging/user/<name of your metric>), finish your setting then click on "
Notification" choose which one you prefer to use {email, SMS, Pager Duty}.
Then it's done whenever there is a new instance created you will recive an email or SMS, ...
I hope this will help you.