health-checker

Check the state of a openSUSE MicroOS system after a reboot.

How does this work?

health-checker will be called by a systemd service during the boot process. All services, which should be checked, needs to be listed in the 'After' section.

The health-checker script will call several plugins. Every plugin is responsible to check a special service or condition. For this, the plugin is called with the option check. If this fails, the plugin will exit with the return value 1, else 0. If everyting was fine, the script will create a /var/lib/misc/health-checker.state file with the number of the current, working btrfs subvolume with the root filesystem. If a plugin reports an error condidtion, the health-checker script will take following actions:

1. If the current btrfs root subvolume is not identical with the last known working snapshot, an automatic rollback to that snapshot is made. Normally, if the current btrfs subvolume is not identical to the last working one, this means an update was made, and this update did never boot correctly.
2. If the current btrfs subvolume did already boot successful in the past, the problem is most likely a temporary problem. In this case, we try to reboot the machine again. /var/lib/misc/health-check.rebooted will be created with the current time.
3. If the current btrfs snapshot did already boot successful in the past and if we did try already to solve the problem with a reboot, it doesn't make sense to reboot again. To give the admin the chance and possibility to fix the problem, all plugins will be called with the option stop. At the end, the machine should still run, so that an admin can login, but no service should run, so that nothing can break.