Psycopg2 peer authentication for user postgres

Question

I seem to have correctly installed PostgreSQL 9.5.5. and Psycopg2 on Ubuntu 16.04, and can log in via:

sudo -u postgres psql

If I then issue \conninfo, I get the following:

You are connected to database "postgres" as user "postgres" via socket in "/var/run/postgresql" at port "5432".

Surely I should be able to connect via psycopg2 in the same fashion as shown here, but the script:

#!/usr/bin/python
import psycopg2
conn = psycopg2.connect("dbname=postgres user=postgres") 
conn.close()

gives me:

psycopg2.OperationalError: FATAL:  Peer authentication failed for user "postgres"

I only want PostgreSQL for personal usage, so I don't want to enable TCP authentication.

How do I correctly use peer authentication with user "postgres" in Psycopg2?

Answer 1

You need to supply the host

conn = psycopg2.connect("dbname='template1' user='dbuser' host='localhost' password='dbpass'")

Answer 2

Peer authentication works by comparing the Postgres username in your connection string to the name of the Linux user who is running the script.

Try running your Python script with sudo -u postgres.