How to use volume in docker compose for postgres?

About your docker-compose file

1. Firstly I thought it's because you don't use 'links' option to link your postgres container to web container - it's good practice if you don't expand ports - but you expand postgres port.

2. If you want use inheritance from the image you postedInstead of using this line:

my_image/postgresql:9.3

use:

docker/postgres

and create path docker/postgres and there place Dockerfile with inharitance from container you want.

3. I always use sharing volumes in docker-compose.yml like this:

   .:/var/www/html

where . is my project path where I place my code files.

Image I created to test this case

I don't have your all docker files structure to reproduce this error and fix it, so I created docker-compose which should match your needs or help to fix your issue:

version: '2'services:  web:    build: docker/web    ports:      - "8080:8080"    links:      - dbpostgres     volumes:      - .:/var/www/html   # I will share my code so I map this path  dbpostgres:    image: postgres    volumes:      - /private/var/lib/postgresql:/var/lib/postgresql    ports:      - "5432:5432"    environment:      POSTGRES_USER: pguser      POSTGRES_PASSWORD: pguser      POSTGRES_DB: pgdb

Notes:

1. I will recommend use official postgres image

2. I left comments next to the lines.

How I made connection:

host=dbpostgres port=5432 dbname=pgdb user=pguser password=pguser

Because my web container know host dbpostgres(image name and domain name) now - I link them using links.

If you need database from existing container

If you need database from your existing container just use option docker cp to copy database localy:

docker cp posgres_test:/var/lib/postgresql /private/var/lib/postgresql

where /private/var/lib/postgresql is path on your localhost.You need also change credentials to db in docker-compose to your old credentials.You have to do it before run docker-compose because if db doesn't exist, will be crated.

Any questions, let me know.

If the volume is external and already existing before the use of docker-compose you should declare it external, or else docker compose will create a new volume with the project name as prefix.

volumes:  test_volume:   external: true

Docs for external using compose v3 (mostly similar to v2): https://docs.docker.com/compose/compose-file/compose-file-v3/#external

I think it sould be something like this for you.

docker run -itd -p 5432:5432 --name postgres_test -v /path/in/your/host :/path/in/your/container postgres_test psql -h 192.168.99.100 -p 5432 -U pguser -W pgdb

Read Docker docs(https://docs.docker.com/engine/tutorials/dockervolumes/), watch tutorials (there is a Docker Youtube channel whith great tutorials) and read other topics before posting a new one...