It's a docker container that contains parsedmarc and MaxMind's geoipupdater.
A great tool to parse DMARC reports. Source is on https://domainaware.github.io/parsedmarc/
You can get the docker image here: https://github.com/jdeluyck/parsedmarc/pkgs/container/parsedmarc
There's one volume to mount, to /config. This will give you access to the GeoIP.conf and parsedmarc.ini files.