Docker - Can't share data between containers within a volume (docker-compose 3)

Question

I have some containers for a web app for now (nginx, gunicorn, postgres and node to build static files from source and a React server side rendering). In a Dockerfile for the no

Answer 1

Explanation of what happens step by step

Dockerfile.node

    ...
    COPY ./client /usr/src
    ...

docker-compose.yml

services:
  ...
  node:
    ...
    volumes:
      - ./server/nginx.conf:/etc/nginx/nginx.conf:ro
      - vnode:/usr/src
  ...
volumes:
  vnode:

1. docker-compose up creates with this Dockerfile.node and docker-compose section a named volume with data saved in /usr/src.

---

Dockerfile.nginx

FROM nginx:latest

COPY ./server/nginx.conf /etc/nginx/nginx.conf

RUN mkdir -p /var/www/tg/static

EXPOSE 80
EXPOSE 443

CMD ["nginx", "-g", "daemon off;"]

2. That produces that nginx containers created with docker-compose will have an empty /var/www/tg/static/

---

docker-compose.yml

 ...
 nginx:
    build:
      context: .
      dockerfile: ./Dockerfile.nginx
    container_name: tg_nginx
    restart: always
    volumes:
      - ./server/nginx.conf:/etc/nginx/nginx.conf:ro
      - vnode:/var/www/tg/static
    ports:
      - "80:80"
      - "443:443"
    depends_on:
      - node
      - gunicorn
    networks:
      - nw_web_tg

 volumes:
   vdata:
   vnode:

3. docker-compose up will produce that vnode named volume is created and filled with data from /var/www/tg/static (empty by now) to existing vnode.

So, at this point, - nginx container has /var/www/tg/static empty because it was created empty (see mkdir in Dockerfile.nginx) - node container has /usr/src dir with client file (see that was copied in Dockerfile.node) - vnode has content of /usr/src from node and /var/www/tg/static from nginx.

Definitively, to pass data from /usr/src from your node container to /var/www/tg/static in nginx container you need to do something that is not very pretty because Docker hasn't developed another way yet: You need to combine named volume in source folder with bind volume in destination:

 nginx:
     build:
       context: .
       dockerfile: ./Dockerfile.nginx
     container_name: tg_nginx
     restart: always
     volumes:
       - ./server/nginx.conf:/etc/nginx/nginx.conf:ro
       - /var/lib/docker/volumes/vnode/_data:/var/www/tg/static
     ports:
       - "80:80"
       - "443:443"
     depends_on:
       - node
       - gunicorn
     networks:
       - nw_web_tg

Just change in docker-compose - vnode:/var/www/tg/static by - /var/lib/docker/volumes/vnode/_data:/var/www/tg/static

Answer 2

Two changes you need. In your node service add the volume like:

volumes:
  - vnode:/usr/src/bundle_client

Since you want to share /usr/src/bundle_client you should NOT be using /usr/src/ because that will share the full folder and the structure too.

And then in your nginx service add the volume like:

volumes:
  - type: volume
    source: vnode
    target: /var/www/test/static
    volume:
      nocopy: true

The nocopy: true keeps our intention clear that on initial map of the container the content of the mapped folder should not be copied. And by default the first container to get mapped to the volume will get the contents of the mapped folder. In your case you want this to be the node container.

Also before testing make sure you run below command to kill the cached volumes:

docker-compose down -v

You can see during my test the container had the files: