[Fixed]-Linking Django and Postgresql with Docker

The Dockerfile for your Django image should not expose port 5432 as no Postgresql server will be running in any container created from that image:

FROM python:3-onbuild
EXPOSE 8000
CMD ["/bin/bash"]

Then as you are running the Django container linking it with

--link my-postgres:my-postgres

your settings for the database are incorrect.

In the Django container: 127.0.0.1 refers to the Django container which isn’t running any service listening on port 5432.

So your settings.py file should be:

  DATABASES = {
   'default': {
       'ENGINE': 'django.db.backends.postgresql_psycopg2',
       'NAME': 'mydb',                      
       'USER': 'postgres',
       'PASSWORD': '',
       'HOST': 'my-postgres',                      
       'PORT': '5432',                      
    }
  }

As you run your Django container with:

sudo docker run --link my-postgres:db -v /home/mpmsp/project/ezdict/ezbkend:/usr/src/app -name my-app -i -t my-app

then your settings.py file would have to be:

  DATABASES = {
   'default': {
       'ENGINE': 'django.db.backends.postgresql_psycopg2',
       'NAME': 'mydb',                      
       'USER': 'postgres',
       'PASSWORD': '',
       'HOST': 'db',                      
       'PORT': '5432',                      
    }
  }