How to connect to localhost postgres database from docker container? - postgresql

Question

I'm configured my project to docker. I have database that have been used in non-docker period and now I want to connect my docker-compose db service to it. But when I write docker-compose up - existing database not used - new one created instead (I suspect, docker container simply doesn't see the database). If I do nonsense please let me know. Maybe I shoud migrate my server db into container.
Here is my docker-compose.yml:
services:
db:
restart: always
image: postgres:latest
environment:
- POSTGRES_DB=mydb
- POSTGRES_PASSWORD=p#ssw0rd
- POSTGRES_USER=root
ports:
- "5432:5432"
volumes:
# We'll mount the 'postgres-data' volume into the location Postgres stores it's data:
- postgres-data:/var/lib/postgresql/data
web:
build: .
command: bash -c "python manage.py collectstatic --noinput && ./manage.py migrate && ./run_gunicorn.sh"
volumes:
- .:/code
- /static:/static
ports:
- 443:443
depends_on:
- db
nginx:
restart: always
image: nginx:latest
ports:
- 80:80
volumes:
- ./misc/nginx.conf:/etc/nginx/conf.d/default.conf
- /static:/static
depends_on:
- web

Answer 1

I think, the canonic approach is to have your DB engine running in container while storing the data on the persistent storage (map the volume to your hard disk).
So I would use the Postgres in docker as ServerDB, as you suggested.

Answer 2

If you only want your application connect to the external database, declare it as an external host:
version: '2'
services:
web:
build: .
command: bash -c "python manage.py collectstatic --noinput && ./manage.py migrate && ./run_gunicorn.sh"
volumes:
- .:/code
- /static:/static
ports:
- 443:443
extra_hosts:
- "db:192.168.1.2"
nginx:
restart: always
image: nginx:latest
ports:
- 80:80
volumes:
- ./misc/nginx.conf:/etc/nginx/conf.d/default.conf
- /static:/static
depends_on:
- web
Just be sure your application reference the database as db and replace the ip I put there with your host ip.
Regards