How to fix heroku connection error when deploying my Django app

could not connect to server: No such file or directory Is the server running locally and
accepting connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

The following error is what I get when I open up my site on heroku. I'm not sure what is going on, but my settings are as follows...

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': os.environ.get('DB_NAME'),
    }
}

pushing to heroku master works fine but just when opening up my app heroku open I get that error and I am not sure how to fix it.

I have also django_heroku.settings(locals()) at the end of my settings.py file and my DB_NAME is a config var of the name of the database on my Heroku app.