I came, updated and crashed the system
From time to time I just run
apt-get update
apt-get upgrade
to update to all the latest versions. I'm not a big fan of reading release change documents. Most of the time this works fine...this time, it didn't.
I was running on Icinga 2.3.4 and I tried to update to the new 2.5.x release. The update worked pretty well... but afterwards I was unable to start the service
It's all about the database
I found out after most of the big release changes, the database schema needs an update. The sql files to do so are installed during upgrade, pretty straight forward. You can find them here
Let's connect to the db server and update the schema
mysql --host=x.x.x.x --user=myUsername --password=myPassword myIcingaDb < /usr/share/icinga2-ido-mysql/schema/upgrade/<version>.sql
Restart the icinga2 service
done