Hey guys,
I had this problem with the virtual machine after following these instructions https://musicbrainz.org/doc/MusicBrainz_Server/Setup and they make it seem like you should be able to access things on port 8080, 5000 and 15432 without doing more than booting up the vm.
Only port 5000 was available, so to get access to postgres I added the missing port forwarding rule to virtualbox, and edited the docker-compose.yml by adding ports: "5432:5432" under services > db and restarting with ./bin/reset-containers.
This is a totally new setup. I was wondering if I did something wrong, or if I should submit a bug report.