SQLAlchemy (psycopg2.OperationalError) fe_sendauth：未提供密码

Question

I'm having this authentication issue when trying to connect to a postgres db using sqlalchemy. This is how I'm connection:

db_url = 'postgresql+psycopg2:///<role>:<pass>@localhost:5432/basketball'
Engine = create_engine(db_url, echo=False)
SessionMaker = ORM.sessionmaker(bind=Engine, autoflush=False)
Session = ORM.scoped_session(SessionMaker)

This is how I set up /etc/postgresql/9.3/main/pg_hba.conf

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     md5
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

Then, when accessing the db I get:

SQLAlchemy  (psycopg2.OperationalError) fe_sendauth: no password supplied 

Answer 1

As @univerio commented , the problem is the structure of the connection url.

The standard url structure is

dialect+driver://username:password@host:port/database

The url

db_url = 'postgresql+psycopg2:///<role>:<pass>@localhost:5432/basketball'

describes a Postgresql database named <role>:<pass>@localhost:5432/basketball with no explicit credentials or hostname defined, hence the error message.