Override container hostname does not work for syslogs

To illustrate my problem, please see this:

docker run --hostname=rogier --rm=true --log-driver=syslog --log-opt syslog-address=udp://:514 --name rogier alpine ping 127.0.0.1

I run a container which outputs the result of the ping command. I also specified remote logging through syslog. This all works and the container logs are indeed sent to syslog. Here is an example:

Jan 20 10:13:09 localhost.localdomain 3db116852935[16001]: 64 bytes from 127.0.0.1: seq=2 ttl=64 time=0.096 ms
Jan 20 10:13:10 localhost.localdomain 3db116852935[16001]: 64 bytes from 127.0.0.1: seq=3 ttl=64 time=0.079 ms

Now my problem is: I would expect the value 3db116852935 to be rogier (due to the fact that I explicitly set the container hostname). For some reason I still get a dynamic generated hostname here.

[EDIT]
Sorry, should have read the docs a bit better. Turns out that I can easily solve it by specifying tags: --log-opt tag={{.Name}}

Another question: do I for some reason have control of the first part: localhost.localdomain? Can I overrule the docker engine w.r.t. this value?