Problem:
When attempting to start Icinga, the service fails to start due to a missing hostgroup 'swift'.
The issue is also present when validating the Icinga configuration with sudo /usr/sbin/icinga -v /etc/icinga/icinga.cfg:
Error: Could not find any hostgroup matching 'swift' (config file '/etc/icinga/objects/puppet_hosts.cfg', starting on line 26664) Error processing object config files!