icinga2/test/config/6105.conf

object HostGroup "6105-bar" {
  assign where match("6105-keks*", host.name)
  vars.foo = "bar"
}

object Host "6105-keks" {
  import "test-generic-host"
  address = "12.3.4"
}

apply Service "6105-foo" {
  import "test-generic-service"
  check_command = "ping4"
  assign where "6105-bar" in host.groups
}

object ServiceGroup "6105-bar" {
  assign where service.name == "6105-foo"
  vars.bar = "foo"
}