Super! It worked! Thanks very much!
I had a problem when launching the sudo docker-compose up local server:
"Error starting userland proxy: listen tcp 0.0.0.0:5432: bind: address already in use"
So I had to use sudo netstat --listening --programs|grep 5432 to find out what was using it. And then I killed this process.
Read more about that (boring)
I don’t know why something (called postgresql or postgres I think) was listening to this port, even if musicbrainz-docker was not running any more.
Maybe because I had just installed a pgadmin3 on the same PC where MBS-docker is running?
I removed pgadmin3 and reboot but still the port was used and musicbrainz-docker could not launch.
Problem and its solution sounded like Error while importing DATABASE dump of bookbrainz on my local setup.
So I killed the process that was using port 5432, and could relaunch musicbrainz-docker OK, then.
I hope I won’t have to redo that kill thing everytime, now.
@dns_server Thanks for your advice DBeaver. It looks good but it’s not available in Debian packages.
For the musicbrainz-docker database manip., I accessed it remotely from a Raspberry Pi (because it’s where I wanted to test a fix to some issue I had with MBS) with pgcli (because postgresql-client’s psql did not work good for me, see my previous post).
I first installed GUI clients (4 or 5 randomly found in apt, including tora, the only one with simple name I can remember) there (on RPi), none were working so I installed this pgcli command line client.
But it was before I found out why nothing was working (Publish ports of all services, see my previous post).
After all that I wanted to retry a GUI client, as you advised me too.
But I shouldn’t have installed it this time on the same PC as where musicbrainz-docker was running.
I installed pgadmin3 on the same Debian PC where musicbrainz-docker is running.
It’s the first PG client I install on this PC.
But at this very moment, I got this error that 5432 port was in use when I tried to start docker.
So I removed the client hoping docker would resume. But no… 
I had to do that kill thing. Maybe now I will always have to do that kill thing… 
BTW PostgreSQL is really the worst program name ever.
Horribly ugly, impossible to spell, to pronounce, to remember.
Hopefully, I can apparently call it PG, as confirmed by the abbreviation plug-in.
They should have asked me a name (SUPER-DB, DATACOOL, any stupid name would have been prettier)