I just tried switching from docker-compose to docker stacks/kubernetes. In compose I was able to specify where the postgres data volume was and the data persisted nicely.

volumes:
- ./postgres-data:/var/lib/postgresql/data

I tried doing the same thing with the stack file and I can connect to the pod and use psql to see the schema but none of the data entered from docker-compose is there.

Any ideas why this might be?

Here's the stack.yml

version: '3.3'

    services:

      django:
        image: image
        build: 
          context: .
          dockerfile: docker/Dockerfile    
        deploy:
          replicas: 5
        environment:
          - DJANGO_SETTINGS_MODULE=config.settings.local
          - SECRET_KEY=password
          - NAME=postgres
          - USER=postgres
          - HOST=db
          - PASSWORD=password
          - PORT=5432
        volumes:
          - .:/application
        command: ["gunicorn", "--bind 0.0.0.0:8000", "config.wsgi"]
        ports:
          - "8000:8000"
        links:
         - db  

      db:
        image: mdillon/postgis:9.6-alpine
        volumes:
          - ./postgres-data:/var/lib/postgresql/data