(Don’t do this!) Note to self; Is your shutdown command causing an error for your packer build? Try this.

Don’t do this! Turns out I was doing this wrong. The below code is only needed if you’ve got things wrong, and you should instead be using keep_vm = "on_success". The more you know, eh?

If you’ve got a command in your packer script that looks like this:

provisioner "shell" {
  inline = ["shutdown -h now"]
}

Try running this instead:

provisioner "shell" {
  inline = [
    "echo Provisioning complete. Shutting down.",
    "(sleep 5 ; shutdown -h now) &"
  ]
}

This will force packer to execute a command which is pushed into the background, returning a return code (RC) of 0, which the system will interpret as a successful result. 5 seconds later the machine will shut itself down by itself.