title: Volume changes not persistent after "docker-compose run" command (Django's collectstatic)
body: <p>I have a Django environment that I create with Docker Compose, and I'm trying to use <code>manage.py collectstatic</code> to copy my site's static files to a directory in the container.  This directory (/usr/src/app/static) is also a Docker Volume.  </p>
  
  <p>After building my docker containers (<code>docker-compose build</code>), I run <code>docker-compose run web python manage.py collectstatic</code>, which works as expected, but my web server (Nginx) is not finding the files, nor are there any files when I run <code>docker-compose run web ls -la /usr/src/app/static</code>.</p>
  
  <p>Any ideas on what I'm doing wrong?</p>
  
  <p>(Note: I don't have <code>manage.py collectstatic</code> in my Dockerfile because my setup needs my ".env" file loaded, and I didn't see a way to load this in the Dockerfile. In either case, I would like to know why Docker Compose doesn't work as I'm expecting it to.)</p>
  
  <p>Here are my config files:</p>
  
  <pre><code>## docker-compose.yml:
  web:
    restart: always
    build: .
    expose:
      - "8000"
    links:
      - postgres:postgres
    volumes:
      - /usr/src/app/static
      - .:/code
    env_file: .env
    command: /usr/local/bin/gunicorn myapp.wsgi:application -w 2 -b :8000 --reload
  
  nginx:
    restart: always
    build: ./config/nginx
    ports:
      - "80:80"
    volumes:
      - /www/static
    volumes_from:
      - web
    links:
      - web:web
  
  postgres:
    restart: always
    image: postgres:latest
    volumes:
      - /var/lib/postgresql
    ports:
      - "5432:5432"
  
  
  ## Dockerfile:
  FROM python:3.4.3
  RUN mkdir /code
  WORKDIR /code
  ADD . /requirements/ /code/requirements/
  RUN pip install -r /code/requirements/docker.txt
  ADD . /code/
  </code></pre>