icinga2 package does by default have a dependency on mysql57 and postgres client libraries, problem is I'm using MariaDB on all my hosts and mysql57 libraries conflict with that; this would force me to recompile the package not only on the icinga2 master (which is OK to me) but also on each and every agent, which is a bit of an inconvenience; it would be nice, if possible, to create a sub-port intended to be deployed on agent nodes, which by default skips all database dependencies (and anything else master-related you can think about, I'm no icinga2 expert myself).
Over to new maintainer
current is MySQL 8.0 If there are further problems, reopen the PR with a detailed error description, with logs and a current configuration.