Docker compose not persisting data

Question

I have the following docker-compose.yml file:

version: '2'
services:
  web:
    image: myspringapp:1
    ports:
      - "8080:8080"
    depends_on:
      - myspringapp_postgres
  myspringapp_postgres:
    image: postgres:9.4 
    ports:
      - "5432:5432"
    volumes:
      - ./pgdata:/var/lib/postgresql/data
volumes:
  pgdata: {}

myspringapp is a docker image I build previously. The problem with this is that the data is lost after doing a docker-compose stop. Anyone know what the problem is?

I think you don't need to put `./` after using named volumes, in `volumes: - ./pgdata...` — Murtaza Khursheed Hussain, Dec 04 '17 at 13:26
Is your data present inside `./pgdata` on your local machine at runtime ? — Munchkin, Dec 04 '17 at 13:26
Note that `./pgdata` does **not** refer to your `pgdata` volume; it refers to a directory named `pgdata` in the same directory as your `docker-compose.yml`. That should still work, of course, but the storage will not be where you expect it to be. If you want to use the `pgdata` volume, you need `pgdata:/var/lib/postgresql/data`. — larsks, Dec 04 '17 at 13:31
@Daniel - The data in your postgres container - or your myspringapp container is being lost? — TJ Biddle, Dec 04 '17 at 13:48

score 0 · Answer 1 · answered Dec 04 '17 at 13:32

0

Looks like you're defining a volume, but specifying a bind-mount to be used.

The different here, is a volume is actually it's own isolated "drive" in a sense, where a bind-mount needs to map to a specific file path on your local system.

If you check in your local ./pgdata directory, you should find all your previous data; and to fix your issue you'll want to remove the ./ from that and just specify the name pgdata so that it uses the volume as defined. Of course, this will start you fresh again.

compose-file.yml

version: '2'
services:
  web:
    image: myspringapp:1
    ports:
      - "8080:8080"
    depends_on:
      - myspringapp_postgres

  myspringapp_postgres:
    image: postgres:9.4 
    ports:
      - "5432:5432"
    volumes:
      - pgdata:/var/lib/postgresql/data
volumes:
  pgdata: {}

answered Dec 04 '17 at 13:32

TJ Biddle

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This is pretty much exactly what I said in my comment, but you'll also note that I said, "this should still work". The postgres container should properly persist the data regardless of whether the storage is a docker volume or a local directory provided through a bind mount. Inside the container, they are identical (docker volumes are just bind mounts managed by docker). – larsks Dec 04 '17 at 13:38
that's exactly identical to what I said in my comment, but in short ;) – Murtaza Khursheed Hussain Dec 04 '17 at 13:45
larsks & murtaza-khursheed-hussain Well there's not really much room for anything different :-) Although you are right; this works fine with the bind-mount, unless he was changing directories. – TJ Biddle Dec 04 '17 at 13:47

Docker compose not persisting data

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