Django - (OperationalError) FATAL: Ident authentication failed for user "username"

Question

I've written a simple sqlalchemy-django model, according to this manual: http://lethain.com/replacing-django-s-orm-with-sqlalchemy/, which worked for me pretty well.
My Django is connected to a remote postgresql database, with this settings:

DATABASES = {
'default': {
    'ENGINE': 'django.db.backends.postgresql_psycopg2', # Add 'postgresql_psycopg2', 'postgresql', 'mysql', 'sqlite3' or 'oracle'.
    'NAME': 'wetlab_dev',                               # Or path to database file if using sqlite3.
    'USER': 'limlim',                                 # Not used with sqlite3.
    'PASSWORD': '',                                     # Not used with sqlite3.
    'HOST': 'cab-27',                                   # Set to empty string for localhost. Not used with sqlite3.
    'PORT': '',                                         # Set to empty string for default. Not used with sqlite3.
    }
}

It worked for me a few days ago, but now when I try to load the 'homepage' again, it shows me the following error message:

(OperationalError) FATAL:  Ident authentication failed for user "limlim"    

The sqlalchemy engine-configuration is:

CONNECTION_STR = 'postgresql://limlim:@cab-27/wetlab_dev'

engine = sqlalchemy.create_engine(CONNECTION_STR)   

It seems like I haven't changed anything that is related to the database configurations, but still I get this error message.
Also, when I try to connect to the database on the remote server with my username, I succeed doing it, so I guess it's not a problem of permissions for my username to get to this database.

What can be done to overcome this error?

Answer 1

Your pg_hba.conf is configured to use 'ident' authentication for connections from localhost (127.0.0.1). You need it to be changed to md5 for your database and user combination.

Answer 2

@Craig is right, have to update the authentication method of the database user in the file pg_hba.conf, here what I've done:

sudo nano /var/lib/pgsql/data/pg_hba.conf

Go to the bottom of the file, then change the method from ident to md5 on the IPv4 and IPv6 rows:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5  # <- here
# IPv6 local connections:
host    all             all             ::1/128                 md5  # <- and here
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                peer
#host    replication     postgres        127.0.0.1/32            ident
#host    replication     postgres        ::1/128                 ident

Happy Coding :)

Answer 3

  local   all             all                                     peer

# IPv4 local connections:
host    all             all             127.0.0.1/32            trust < from ident to trust 
# IPv6 local connections:
host    all             all             ::1/128                 trust < i changed this from ident to trust 
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             127.0.0.1/32            ident
host    replication     all             ::1/128                 ident

Don't forget to restart postgresql:

sudo systemctl restart postgresql