Hi @imonike. Unfortunately, that tutorial appears to leave out a crucial part of the configuration, which is creating the VM image that you will launch when a job requests it. It’s briefly alluded to with the following paragraph under Jenkins Cloud Setup:
Note: The instance requires java8 installed and on the default path. Create a VM, install Java8 and create a new OS image in your GCP project. Packer can also be used to achieve this. More info here.
Unfortunately, the “More info here” text isn’t a clickable link and I’m not sure how it gets set up as I’ve never used Google Cloud myself. The other thing is that that paragraph is likely out of date: you need to have the same version of Java installed on the VM as you are using to run Jenkins, which will be a minimum of Java 11 if you’re running Jenkins 2.357 weekly or Jenkins 2.361.1 LTS or later.
The templates dropdown is likely empty because the Jenkins plugin is querying Google Cloud using the service account you created and looking for any VM images that it can launch, but it’s not finding any. That would also prevent it from creating any agents using that configuration (as there’s nothing for it to launch).