A very simple socat based syslog server designed to listen to syslog on TCP, UDP or a UNIX socket /syslog/sock and print any messages to stdout so that they get picked up by the docker log system and can be accessed via tools like logspout.
$ docker run -d factorish/syslog [-t tcp|udp|socket]
Listen on TCP 5140 on host:
$ docker run -d -p 5140:514 factorish/syslog -t tcp
Listen on UDP 5140 on host:
$ docker run -d -p 5140:514/udp factorish/syslog -t udp
Listen on a socket which is volume mounted into another container:
$ docker run -d --name syslog -v /syslog/socket factorish/syslog -t socket
$ docker run -ti --volumes-from syslog defensative/socat-ubuntu UNIX:/syslog/socket -
test
test
test
CTRL^C
$ docker logs syslog
==> syslog listening on socket
test
test
test