title: Can't connect to server error Google App Engine Static Files Issue
body: <p>I’m having difficulties switching my Google App Engine web app from a <code>standard</code> to a <code>flex</code> environment  using Django. I need to switch to a flex environment since I am using the module <code>pdf2image</code> in my app, which uses <code>poppler</code>. Here are my app.yaml, Dockerfile, and snippets from my settings.py. </p>
  
  <p>Note: </p>
  
  <ul>
  <li>Before making these changes the app ran as it should locally</li>
  <li>There are probably multiple errors and we would appreciate any feedback on which parts to fix. Thanks!</li>
  </ul>
  
  <p>Here is the error which is showing:</p>
  
  <pre><code>File "/env/lib/python3.7/site-packages/MySQLdb/__init__.py", line 84, in Connect return Connection(*args, **kwargs) 
  File "/env/lib/python3.7/site-packages/MySQLdb/connections.py", line 164, in __init__ super(Connection, self).__init__(*args, **kwargs2) django.db.utils.OperationalError: (2003, "Can't connect to MySQL server on '127.0.0.1' (111)")
  </code></pre>
  
  <p>Here are our relevant code snippets:</p>
  
  <p>app.yaml:</p>
  
  <pre><code># [START django_app]
  runtime: custom
  env: flex
  handlers:
  # This configures Google App Engine to serve the files in the app's
  # static directory.
  - url: /static
    static_dir: static/
  # This handler routes all requests not caught above to the main app.
  # It is required when static routes are defined, but can be omitted
  # (along with the entire handlers section) when there are no static
  # files defined.
  - url: /.*
    script: auto
  # [END django_app]
  </code></pre>
  
  <p>Dockerfile: </p>
  
  <pre><code>FROM gcr.io/google-appengine/python
  
  # Create a virtualenv for dependencies. This isolates these packages from
  # system-level packages.
  # Use -p python3 or -p python3.7 to select python version. Default is version 2.
  RUN apt-get update
  RUN apt-get install poppler-utils --assume-yes
  RUN virtualenv -p python3.7 /env
  
  # Setting these environment variables are the same as running
  # source /env/bin/activate.
  ENV VIRTUAL_ENV /env
  ENV PATH /env/bin:$PATH
  
  # Copy the application's requirements.txt and run pip to install all
  # dependencies into the virtualenv.
  ADD requirements.txt /app/requirements.txt
  RUN pip install -r /app/requirements.txt
  
  # Add the application source code.
  ADD . /app
  
  # Run a WSGI server to serve the application. gunicorn must be declared as
  # a dependency in requirements.txt.
  CMD gunicorn -b :$PORT main:app
  </code></pre>
  
  <p>settings.py: </p>
  
  <pre><code># STATIC_URL = 'https://storage.googleapis.com/tulaibucket/static/'
  
  if os.getenv('GAE_APPLICATION', None):
      # Running on production App Engine, so use a Google Cloud SQL database.
      DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.mysql',
              'HOST': ‘MYHOST’,
              'USER': ‘MYUSER’,
              'PASSWORD': ‘MYPASSWORD’,
              'NAME': ‘DBNAME’,
          }
      }
  else:
      # Running in development, so use a local MySQL database.
      DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.mysql',
              'HOST': '127.0.0.1',
              'PORT': '3306',
              'NAME’: ‘DBNAME’,
              'USER': ‘MYUSER’,
              'PASSWORD': ‘MYPASSWORD’,
          }
      }
  </code></pre>