title: ImportError: No module named flask_restful
body: <p>I am trying to deploy appengine flex python app but getting the following in Stackdriver log stderr  after deployment </p>
  
  <pre><code>  File "/env/local/lib/python2.7/site-packages/gunicorn/arbiter.py", line 578, in spawn_worker
      worker.init_process()
    File "/env/local/lib/python2.7/site-packages/gunicorn/workers/base.py", line 126, in init_process
      self.load_wsgi()
    File "/env/local/lib/python2.7/site-packages/gunicorn/workers/base.py", line 135, in load_wsgi
      self.wsgi = self.app.wsgi()
    File "/env/local/lib/python2.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
      self.callable = self.load()
    File "/env/local/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 65, in load
      return self.load_wsgiapp()
    File "/env/local/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 52, in load_wsgiapp
      return util.import_app(self.app_uri)
    File "/env/local/lib/python2.7/site-packages/gunicorn/util.py", line 352, in import_app
      __import__(module)
    File "/home/vmagent/app/my_service/entry_point.py", line 5, in &lt;module&gt;
      import flask_restful as restful
  ImportError: No module named flask_restful
  </code></pre>
  
  <p>entry_point.py in line 5 has </p>
  
  <pre><code>import flask_restful as restful
  </code></pre>
  
  <p>And my requirement.txt has</p>
  
  <pre><code>Flask-RESTful==0.3.6
  gunicorn==19.7.1
  </code></pre>
  
  <p>Not sure why its still complaining about Flask-Restful</p>