Problems in connecting to MusicBrainz database using psycopg2

Question

I am trying to connect to the MusicBrainz database using the psycopg2 python's module. I have followed the instructions presented on http://musicbrainz.org/doc/MusicBrainz_Server/Setup, but I cannot succeed in connecting. In particular I am using the following little script:

import psycopg2
conn = psycopg2.connect( database = 'musicbrainz_db', user= 'musicbrainz', password = 'musicbrainz', port = 5000, host='10.16.65.250')
print "Connection Estabilished"

The problem is that when I launch it, it never reaches the print statement, and the console (I'm on linux) is block indefinitely. It does not even catches the ctrl-c kill, so I have to kill python itself in another console. What can cause this?

Answer 1

You seem to be mistaking MusicBrainz-Server to be only the database. What's running on port 5000 is the Web Server. You can access http://10.16.65.250:5000 in the browser.

Postgres is also running, but listens on localhost:5432. This works:

import psycopg2
conn = psycopg2.connect(database="musicbrainz_db",
                        user="musicbrainz", password="musicbrainz",
                        port="5432", host="localhost")
print("Connection established")

In order to make postgres listen to more than localhost you need to change listen_addresses in /etc/postgresql/9.1/main/postgres.conf and make an entry for your (client) host or network in /etc/postgresql/9.1/main/pg_hba.conf.

My VM is running in a 192.168.1.0/24 network so I set listen_addresses='*' in postgres.conf and in pg_hab.conf:

host    all             all             192.168.1.0/24          trust

I can now connect from my local network to the DB in the VM.

---

Depending on what you actually need, you might not want to connect to the MusicBrainz Server via postgres. There is a MusicBrainz web service you can access in the VM. Example: http://10.16.65.250:5000/ws/2/artist/c5c2ea1c-4bde-4f4d-bd0b-47b200bf99d6. In that case you might be interested in a library to process the data: python-musicbrainzngs.

EDIT: You need to set musicbrainzngs.set_hostname("10.16.65.250:5000") for musicbrainzngs to connect to your local VM.