title: Docker file update volume
body: <p>Hello I have a project in elixir, but I have doubts about how I can make a link whenever I update my files locally update the docker,
  so you don't have to use docker-compose up every time something is updated.</p>
  <p>my docker file :</p>
  <pre><code>    FROM elixir:alpine
      
      RUN apk add --update --no-cache curl py-pip
      RUN apk add --no-cache build-base git
      
      WORKDIR /app
      
      RUN mix local.hex --force &amp;&amp; \
              mix local.rebar --force
      
      COPY mix.exs mix.lock ./
      COPY config config
      
      RUN mix do deps.get, deps.compile
      
      COPY priv priv
      COPY lib lib
      
      COPY numbers.csv numbers.csv
      
      COPY docker-entrypoint.sh docker-entrypoint.sh
      
      EXPOSE 4000
  
  docker-compose:
  
  version: &quot;3.7&quot;
  services:
    app:
        restart: on-failure
        build: .
        command: /bin/sh docker-entrypoint.sh
        ports: 
          - &quot;4000:4000&quot;
        depends_on: 
          - postgres-db 
        links:
          - postgres-db
        env_file:
          - .env
    postgres-db:
        image: &quot;postgres:12&quot;
        restart: always
        container_name: &quot;postgres-db&quot;
        environment: 
          POSTGRES_PASSWORD: ${DB_PASS}
          POSTGRES_USER: ${DB_USER}
          POSTGRES_DB: ${DB_NAME}
        ports: 
          - &quot;5432:5432&quot;
  </code></pre>
  <p>folder structure:</p>
  <p><a href="https://i.stack.imgur.com/DNsSx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DNsSx.png" alt="enter image description here" /></a></p>