Publish to a topic using Google Cloud Pubsub within Compute Engine

Question

I am quite new to the GCP platform. I wanted to find out if it were possible to publish to a Google Cloud Pubsub topic from within a Preemptible Compute Engine VM's shutdown script, other than performing REST calls to the PubSub API?

I would like to notify myself each time a Compute Engine Preemptible VM has been scheduled to be preempted.

Answer 1

There is a comprehensive tutorial here . Briefly, it uses the Python Client Library to publish to a specific topic ( more here , including other languages). The script and credentials are saved in an image to be able to automate it for future VMs. Then you can just invoke the script with the --metadata flag where the key would be shutdown-script and the value the bash script that calls the code. For example:

gcloud compute instances create <instance-name> --preemptible --image <image-name> \
--zone <zone> --metadata shutdown-script="#! /bin/bash
    sudo su -
    python /path/to/script.py"

Alternatively, instead of saving the image and pointing to the Python script, you could just dump the python code into the bash shutdown script with the -c argument as explained here .