Bitbucket Pipelines - access to another container
Bitbucket docs try to be clear, but it doesn't try to help the user:
PostgreSQL will be available on localhost:5432
The problem is, psql doesn't work as you expect. Their default behavior is connecting to the file socket (/var/run/postgresql/.s.PGSQL.5432), not to localhost.
You must set the host parameter to connect: psql -h localhost