title: how to run gunicorn+bokeh+flask script example (ubuntu)
body: <p>I am trying to run the code below  (borrowed from: <a href="https://github.com/bokeh/bokeh/blob/0.12.14/examples/howto/server_embed/flask_gunicorn_embed.py" rel="nofollow noreferrer">https://github.com/bokeh/bokeh/blob/0.12.14/examples/howto/server_embed/flask_gunicorn_embed.py</a>). in Ubuntu 16 but I cannot seem to get it to work. In a ssh, I entered <code>gunicorn - 4 flask_gunicorn_embed:app</code> and navigated to each of:
  <code>127.0.0.1:8000</code>
  <code>localhost:8000</code>
  <code>"myhostname":8000</code>
  but to no avail. The log says <code>Listening at : http://127.0.0.1:8000</code>. Can someone guide me on how to get it working?</p>
  
  <pre><code>from flask import Flask, render_template
  
  from tornado.httpserver import HTTPServer
  from tornado.ioloop import IOLoop
  
  from bokeh.application import Application
  from bokeh.application.handlers import FunctionHandler
  from bokeh.embed import server_document
  from bokeh.layouts import column
  from bokeh.models import ColumnDataSource, Slider
  from bokeh.plotting import figure
  from bokeh.server.server import BaseServer
  from bokeh.server.tornado import BokehTornado
  from bokeh.server.util import bind_sockets
  from bokeh.themes import Theme
  
  if __name__ == '__main__':
      print('This script is intended to be run with gunicorn. e.g.')
      print()
      print('    gunicorn -w 4 flask_gunicorn_embed:app')
      print()
      print('will start the app on four processes')
      import sys
      sys.exit()
  
  from bokeh.sampledata.sea_surface_temperature import sea_surface_temperature
  
  app = Flask(__name__)
  
  def modify_doc(doc):
      df = sea_surface_temperature.copy()
      source = ColumnDataSource(data=df)
  
      plot = figure(x_axis_type='datetime', y_range=(0, 25), y_axis_label='Temperature (Celsius)',
                    title="Sea Surface Temperature at 43.18, -70.43")
      plot.line('time', 'temperature', source=source)
  
      def callback(attr, old, new):
          if new == 0:
              data = df
          else:
              data = df.rolling('{0}D'.format(new)).mean()
          source.data = ColumnDataSource(data=data).data
  
      slider = Slider(start=0, end=30, value=0, step=1, title="Smoothing by N Days")
      slider.on_change('value', callback)
  
      doc.add_root(column(slider, plot))
  
      doc.theme = Theme(filename="theme.yaml")
  
  # can't use shortcuts here, since we are passing to low level BokehTornado
  bkapp = Application(FunctionHandler(modify_doc))
  
  bokeh_tornado = BokehTornado({'/bkapp': bkapp}, extra_websocket_origins=["localhost:8000"])
  bokeh_http = HTTPServer(bokeh_tornado)
  
  # This is so that if this app is run using something like "gunicorn -w 4" then
  # each process will listen on its own port
  sockets, port = bind_sockets("localhost", 0)
  bokeh_http.add_sockets(sockets)
  
  @app.route('/', methods=['GET'])
  def bkapp_page():
      script = server_document('http://localhost:%d/bkapp' % port)
      return render_template("embed.html", script=script, template="Flask")
  
  def bk_worker():
      io_loop = IOLoop.current()
      server = BaseServer(io_loop, bokeh_tornado, bokeh_http)
      server.start()
      server.io_loop.start()
  
  from threading import Thread
  Thread(target=bk_worker).start()
  </code></pre>