title: Auto reloading flask server on Docker
body: <p>I want my flask server to detect changes in code and reload automatically.
  I'm running this on docker container.
  Whenever I change something, I have to build and up again the container. I have no idea where's wrong. This is my first time using flask.</p>
  
  <p>Here's my tree</p>
  
  <pre><code>├── docker-compose.yml
  └── web
      ├── Dockerfile
      ├── app.py
      ├── crawler.py
      └── requirements.txt
  </code></pre>
  
  <p>and code(app.py)</p>
  
  <pre><code>from flask import Flask 
  import requests
  app = Flask(__name__)
  
  @app.route('/')
  def hello_world():
      return 'Hello Flask!!'
  
  if __name__ == '__main__':
      app.run(debug = True, host = '0.0.0.0')
  </code></pre>
  
  <p>and docker-compose</p>
  
  <pre><code>version: '2'
  services:
  
    web:
      build: ./web
      ports:
       - "5000:5000"
      volumes:
       - ./web:/code
  </code></pre>
  
  <p>Please give me some advice. Thank you in advance.</p>