Just run it with your configuration file and data volume/dir mapped
It runs with user/group id 10001
You can print the bundled example configuration file by specifying config
as the first argument
$ docker run --rm -v xbblabs/geoipupdate config
$ docker run --rm -v /etc/geoip.conf:/etc/GeoIP.conf -v geoip-data:/usr/share/GeoIP xbblabs/geoipupdate
# At 12:00 on Wednesday
00 12 * * 3 docker run --rm -v /etc/geoip.conf:/etc/GeoIP.conf -v geoip-data:/usr/share/GeoIP xbblabs/geoipupdate