Question

Per suggestions on SO/SF and other sites, I am using CherryPy as the WSGI server to launch multiple instances of a Python web server I built with Flask. Each instance runs on its own port and sits behind Nginx. I should note that the below does work for me, but I’m troubled that I have gone about things the wrong way and it works “by accident”.

Here is my current cherrypy.conf file:

[global]
server.socket_host = '0.0.0.0'
server.socket_port = 8891
request.dispatch: cherrypy.dispatch.MethodDispatcher()
tree.mount = {'/':my_flask_server.app}

Without diving too far into my Flask server, here’s how it starts:

import flask
app = flask.Flask(__name__)

@app.route('/')
def hello_world():
    return "hello"

And here is the command I issue on the command line to launch with Cherryd:

cherryd -c cherrypy.conf -i my_flask_server

Questions are:

1. Is wrapping Flask inside CherryPy still the preferred method of using Flask in production? https://stackoverflow.com/questions/4884541/cherrypy-vs-flask-werkzeug

2. Is this the proper way to use a .conf file to launch CherryPy and import the Flask app? I have scoured the CherryPy documentation, but I cannot find any use cases that match what I am trying to do here specifically.

3. Is the proper way to launch multiple CherryPy/Flask instances on a single machine to execute multiple cherryd commands (daemonizing with -d, etc) with unique .conf files for each port to be used (8891, 8892, etc)? Or is there a better “CherryPy” way to accomplish this?

Thanks for any help and insight.

Answer 1

I can’t speak for Flask, but I can for CherryPy. That looks like the “proper way”…mostly. That line about a MethodDispatcher is a no-op since it only affects CherryPy Applications, and you don’t appear to have mounted any (just a single Flask app instead).

Regarding point 3, you have it right. CherryPy allows you to run multiple Server objects in the same process in order to listen on multiple ports (or protocols), but it doesn’t have any sugar for starting up multiple processes. As you say, multiple cherryd commands with varying config files is how to do it (unless you want to use a more integrated cluster/config management tool like eggmonster).