Services not honoring search domains

I’m trying to set up search paths in my docker services. I have used the --dns-search-add flag on the docker service update command and can verify its set via docker inspect. I can also see it in /etc/resolv.conf in the container, and yet nslookups etc do not find the record inside the service. When I fully qualify the record i’m able to look it up fine. I’ve verified on the swarm host the same searches work with the same search domain configured. Any ideas on what I’m doing wrong?

Docker Version 17.12.0-ce
OS centos-release-7-4.1708.el7.centos.x86_64