How to use a PostgreSQL container with existing data?

Question

I am trying to set up a PostgreSQL container (https://hub.docker.com/_/postgres/). I have some data from a current PostgreSQL instance. I copied it from /var/lib/postgresq

Answer 1

It looks like the PostgreSQL image is having issues with mounted volumes. FWIW, it is probably more of a PostgreSQL issue than Dockers, but that doesn't matter because mounting disks is not a recommended way for persisting database files, anyway.

You should be creating data-only Docker containers, instead. Like this:

postgres9:
  image: postgres:9.4
  ports:
    - 5432:5432
  volumes_from:
    - pg_data
  environment:
    POSTGRES_PASSWORD: postgres
    POSTGRES_USER: postgres
    PGDATA : /var/lib/postgresql/data/pgdata

pg_data:
  image: alpine:latest
  volumes:
    - /var/lib/postgresql/data/pgdata
  command: "true"

which I tested and worked fine. You can read more about data-only containers here: Why Docker Data Containers (Volumes!) are Good

As for: how to import initial data, you can either:

1. docker cp, into the data-only container of the setup, or
2. Use an SQL dump of the data, instead of moving binary files around (which is what I would do).