How to: Extra boot script

Extra boot script is a way to apply hotfixes at boottime, or to test various things in development.

"Extra boot scripts" are fetched from bootservers to hosts. These are persistent under /state/ebs on laptops. They are executed at boot, and can contain any code, most usually shell scripts but other kinds of executable code can be used. The scripts are fetched depending on the device image name, and all scripts are executed from the most generic to the most specific.

On hosts which never have any bootserver connection there is no automated mechanism to fetch the ebs-scripts to the host, but they can be placed manually under /state/ebs.

Extra boot scripts are executed after all puavo-conf scripts, but before systemd takes control of the boot process.

Example script names are (from the most generic to the most specific):

  puavo.ebs
  puavo-os.ebs
  puavo-os-opinsys.ebs
  puavo-os-opinsys-stretch.ebs
  puavo-os-opinsys-stretch-2018.ebs
  puavo-os-opinsys-stretch-2018-02.ebs
  puavo-os-opinsys-stretch-2018-02-21.ebs
  puavo-os-opinsys-stretch-2018-02-21-124742.ebs
  puavo-os-opinsys-stretch-2018-02-21-124742-amd64.ebs

These must reside under "${IMAGESDIR}/ebs"-directory on bootservers, usually /opt/ltsp/images/debs but this may vary.

This feature is *off* by default, but can be turned on by setting the puavo.admin.run_extra_boot_scripts puavo-conf -variable to true.

The script outputs can be read from /run/puavo/init-puavo.log, as is the case with other puavo-conf scripts.