Units that get installed via `rpm-ostree` on first boot cannot be
enabled by ignition, because they do not exist when it runs `systemctl
preset`. Thus, anything we want to start after its been installed needs
to be explicitly started. To allow this in an extensible fashion, I've
added an `after-install.target` unit and modified the
`install-packages.sh` script to activate this unit once the installation
is complete. The script also re-runs `systemctl preset`, so services
will start automatically on subsequent boots.
The *install-packages.service* unit has to be enabled, and the condition
checking for `/etc/ignition/packages.installed` was inverted.
Sending standard output to the console as well as the journal allows
watching progress.
Some machines may need to install multiple packages for separate use
cases. Requiring each use case to define a systemd unit that runs
`rpm-ostree install` directly would be cumbersome and also quite slow,
as each one would have to run in turn. Instead, now there is a single
*install-packages.service* which installs all of the packages listed in
files in `/etc/ignition/packages.d`. On first boot, all files in that
directory are read and all the packages they list will be installed in a
single `rpm-ostree install` invocation.
Dustin