Sample plugin source

Always start with a current copy of the scaffold plugin repo. This has a few important files in the root directory, including main.go, GNUMakefile, and go.mod, which pins certain versions of the dependencies used by your Go module. It also declares a Go module, which you should rename to your module. Here, we use packer-plugin-nspawn for our module name. Have a look at the repository here: https://github.com/jboero/packer-plugin-nspawn.

The repo contains sample folders for each plugin type:

• builder: We will use this to start a systemd-nspawn machine
• datasource: We will use this to look up the machines and images available
• post-processor: We won’t need one of these so we delete the directory
• provisioner: We also won’t need one of these so we will delete it

The plugin registers itself in the very simple main.go file. Post-processors and provisioners may be added for custom actions but we won’t need anything. Packer...