title: Serving static html file from another directory from flask restful endpoint
body: <p>I have a toy REST application which is structured in a following way:</p>
  
  <pre><code> - client/
     - css/
     - js/
     - index.html
   - server/
     - app.py
     ... some other files  which I use in app.py
  </code></pre>
  
  <p><code>app.py</code> is a flask restful endpoint which looks like this:</p>
  
  <pre><code>app = flask.Flask('some-name')
  
  # a lot of API end points, which look in this way
  @app.route('/api/something', methods=['GET'])
  def func_1():
      ...
  </code></pre>
  
  <p>and now I want to serve my static index html. So after looking at <a href="https://stackoverflow.com/questions/20646822/how-to-serve-static-files-in-flask">this</a>, <a href="https://stackoverflow.com/questions/15883874/python-flask-serving-static-files">this</a> and <a href="http://codepen.io/asommer70/blog/serving-a-static-directory-with-flask" rel="noreferrer">this</a>, I thought that I would be able to serve it easily by adding the following lines:</p>
  
  <pre><code>@app.route('/')
  def home():
      # but neither with this line
      return app.send_static_file('../client/index.html')
      # nor with this
      return flask.render_template(flask.url_for('static', filename='../client/index.html'))
  </code></pre>
  
  <p>I can not see my html file (logs tell me: <code>127.0.0.1 - - [some day] "GET / HTTP/1.1" 404 -</code>). I know that I can move index.html in the server folder but is there a way to serve it from where it is right now?</p>
  
  <p><strong>P.S.</strong> when I added <code>app._static_folder = "../client/"</code> and changed my home function to <code>return app.send_static_file('index.html')</code> I finally started to receive my html file, but all the css/js file that are inside html are returned with 404.</p>