Package: kea-dhcp4-server
Version: 2.2.0-6
1.After clean installation using:
    apt update
    apt install kea-dhcp4-server
necessary directories: /var/log/kea, /var/lib/kea, /var/run/kea were missing (they were left to be created by systemd ???).
So I had to create them manually.

2. There was also a problem with apparmor - I had to change the file /etc/apparmor.d/usr.sbin.kea-dhcp4 adding:
  /var/log/kea/** rwk,
  /run/kea/logger_lockfile wrk,
  /run/kea/kea4-ctrl-socket wrk,
  /run/kea/kea4-ctrl-socket.lock wrk,
and commenting out:
   owner /run/lock/kea/logger_lockfile rwk,
   owner /var/run/kea/logger_lockfile rwk,
Maybe You will be able to achieve the goal in a better way, but it works for me!

3. There was also a problem with start/stop script: /etc/init.d/kea-dhcp4-server
originally it could start the daemon but was unable to stop it.
After replacing: 
           --name $NAME
with:
          --exec $DAEMON
in two locations, it stops it (although sometimes with long delay).

After all this changes the daemon seems to be working - dhclient from other machine is able to get IP assignment.
I hope this information will help managing the package.

With Best Regards,
    Jerzy Sobczyk