title: Docker compose installing requirements.txt
body: <p>In my docker image I am cloning the git master branch to retrieve code. I am using docker-compose for the development environment and running my containers with volumes. I ran across an issue when installing new project requirements from my python requirements.txt file. In the development environment, it will never install new requirements on dev environment because when re-building the image, the latest code is pulled from github.</p>
  
  <p>Below is an example of my dockerfile:</p>
  
  <pre><code>FROM base
  
  # Clone application
  RUN git clone repo-url
  # Install application requirements
  RUN pip3 install -r app/requirements.txt
  
  # ....
  </code></pre>
  
  <p>Here is my compose file:</p>
  
  <pre><code>myapp:
      image: development
      env_file: .env
      ports:
          - "8000:80"
      volumes:
          - .:/home/app
  
      command: python3 manage.py runserver 0.0.0.0:8000
  </code></pre>
  
  <p>Is there any way to install newly added requirements after build on development?</p>