Container files not updated when changed from the host mapped volume - docker

Question

I have the following docker-compose.yml:
version: '3'
services:
web:
build:
context: .
dockerfile: ./.docker/node.dockerfile
volumes:
- D:\Proj\Web:/app
ports:
- '3000:3000'
depends_on:
- 'db'
networks:
- holder-network
restart: on-failure
tty: true
db:
image: mysql:5.7
volumes:
- db_data:/var/lib/mysql
networks:
- holder-network
restart: always
environment:
MYSQL_ROOT_PASSWORD: P#ssw0rd
MYSQL_DATABASE: holder_db
MYSQL_USER: holder_usr
MYSQL_PASSWORD: P#ssw0rd
networks:
holder-network:
driver: bridge
volumes:
db_data:
And the node.dockerfile:
FROM node:7.10
MAINTAINER Juliano Nunes
RUN mkdir /var/www
RUN npm install nodemon -g
WORKDIR /var/www
ADD . /var/www
RUN npm install
CMD nodemon
I'm changing the files under D:\Proj\Web from the host, however it doesn't update the files in the container. Why?

Answer 1

I've found the error. My docker-compose.yml was using /app as the path and node.dockerfile was using /var/www.
Here's the updated (working) version:
version: '3'
services:
web:
build:
context: .
dockerfile: ./.docker/node.dockerfile
volumes:
- D:\Proj\Web:/var/www
ports:
- '3000:3000'
depends_on:
- 'db'
networks:
- holder-network
restart: on-failure
tty: true
db:
image: mysql:5.7
volumes:
- db_data:/var/lib/mysql
networks:
- holder-network
restart: always
environment:
MYSQL_ROOT_PASSWORD: P#ssw0rd
MYSQL_DATABASE: holder_db
MYSQL_USER: holder_usr
MYSQL_PASSWORD: P#ssw0rd
networks:
holder-network:
driver: bridge
volumes:
db_data:

Answer 2

To map a host volume in a container running on docker for windows, you need to ensure your drive is shared into the embedded VM. Otherwise, the directory will mount from the VM's filesystem which will be empty at that location. You need to go into the docker settings on Windows and add the D drive to the shared directory list. See docker's documentation on this here: https://docs.docker.com/docker-for-windows/#shared-drives