Choose non-default port for Postgres in docker/up.sh

[rossturk]

I keep running into situations where I want to run Marquez alongside Airflow (or another system that also runs a Postgres database) and the two docker-compose environments both attempt to start a Postgres database. The "correct" workaround is to create a single docker-compose environment with a shared database for both systems, but this is not always ideal.

It would be nice if we could tell docker/up.sh to start Postgres on an alternate port.

[collado-mike]

TBH, there's not a lot of reason to map the database port to any specific port on the host. The Marquez API will get routed by Docker to whatever port it's actually bound to. The only useful thing we get out of mapping to a specific port is that we can use psql on the command line to query the database during development. docker port marquez-db 5432 is all we really need to find what port to connect to, though

[rossturk]

It's not about accessing the DB, it's about other tools complaining that they can't start their own databases because the port is in use.

[collado-mike]

Yeah, I got it. I'm saying there will be no conflicts if we bind 5432 to a random port (if we change this line to just 5432 instead of 5432:5432).

The API container will still be able to hit the database because docker magic will translate db:5432 to whatever actual port it's bound to. Only commands outside the docker network will have problems (i.e., psql on the command line), but that can be addressed with the docker port command.