Below are screenshots of the proof of the working workflow to trigger a build on push or pull request on the main branch. Here, I updated the README file and triggered a build on push.
Below are screenshots of the proof of the working workflow for deployment in GKE.
There is an error before deployment began. Probably, due to the secret SA key. I have secret key as the private_key that I copied from the JSON file. I will now put the entire JSON secret key file as the secret key on GitHub.
It says that some backend services are in unknown state. Later, we see that in the bottom, it shows that there might be a problem with one of the services. The reason is unknown: could be that the deployment did not go very well because of us or just because GCP is imperfect, or maybe because I am using free trial version of GCP. Nonetheless, it is working: