I have a python web app developed using the bottle framework. My bottle app is web API that provide methods that return JSon data, so no static content is needed. I am trying to deploy it to production using a CherryPy server which is supposed to be robust for production applications.
My web_api.py file (my bottle app) looks something like this:
from bottle import Bottle, request
app = Bottle()
#app.get('/stuff')
def do_stuff():
'''
Method that does stuff.
'''
stuff = {'data': 'some data'}
# Return the environment info as Json data
return stuff
I have a server.py file to launch the Bottle app over the CherryPy server that looks like this:
from my_package.web_api import app
from cherrypy.wsgiserver import CherryPyWSGIServer
server = CherryPyWSGIServer(
('0.0.0.0', 80),
app,
server_name='My_App',
numthreads=30)
server.start()
so when I run my server using this command:
python server.py
My server is successfully started and start listening in port 80 as expected. However once I start my web server I cannot stop it any more. I have tried Ctrl + C which works with the development server but has no effect here. Am I starting the server the right way? How do I stop it once it is running? Is this the correct way to launch a Bottle app over CherryPy?
BTW, I am running python 2.7 in Windows 8.
Your code is correct, you just need to add a try/catch statement:
from my_package.web_api import app
from cherrypy.wsgiserver import CherryPyWSGIServer
server = CherryPyWSGIServer(
('0.0.0.0', 80),
app,
server_name='My_App',
numthreads=30)
try:
server.start()
except KeyboardInterrupt:
server.stop()
You might wanna also consider to do some logging with wsgi-request-logger or something similar.
This are three alternative ways on hosting a WSGI application within cherrypy:
import cherrypy as cp
from cherrypy.wsgiserver import CherryPyWSGIServer
from cherrypy.process.servers import ServerAdapter
from bottle import Bottle
app = Bottle()
#app.get('/stuff')
def do_stuff():
'''
Method that does stuff.
'''
stuff = {'data': 'some dataX'}
return stuff
def run_decoupled(app, host='0.0.0.0', port=8080, **config):
server = CherryPyWSGIServer((host, port), app, **config)
try:
server.start()
except KeyboardInterrupt:
server.stop()
def run_in_cp_tree(app, host='0.0.0.0', port=8080, **config):
cp.tree.graft(app, '/')
cp.config.update(config)
cp.config.update({
'server.socket_port': port,
'server.socket_host': host
})
cp.engine.signals.subscribe() # optional
cp.engine.start()
cp.engine.block()
def run_with_adapter(app, host='0.0.0.0', port=8080, config=None, **kwargs):
cp.server.unsubscribe()
bind_addr = (host, port)
cp.server = ServerAdapter(cp.engine,
CherryPyWSGIServer(bind_addr, app, **kwargs),
bind_addr).subscribe()
if config:
cp.config.update(config)
cp.engine.signals.subscribe() # optional
cp.engine.start()
cp.engine.block()
The run_in_cp_tree and run_with_adapter functions are using the cherrypy engine, which enables the use of plugins to have off-the-shelf auto-reload, pidfile, daemonization, signal management and some more goodies, along with the possibility to create one of your own.
Notice that you can also use the WSGIPathInfoDispatcher to attach multiple wsgi applications on the CherryPyWSGIServer.
Trying to connect any WSGI server to my BottlePy app here in 2019 turned out to be rather tricky(to a noobie like me).
I tried connecting several ones, spent most off my time with CherryPy, which has changed his syntax.
The simpliest to me turned out to be waitress https://waitress.readthedocs.io/en/latest/usage.html
After i figured out how to use it on waitress i got it in cherrypy also. So:
CherryPy http://docs.cherrypy.org/en/latest/advanced.html?highlight=WSGi#host-a-foreign-wsgi-application-in-cherrypy
1)add after imports
import cherrypy as cp
app = bottle.Bottle()
2) change in routes "#bottle" to "#app"
3)add this as main function
cp.tree.graft(app, '/')
cp.server.start()
Waitress
1)add after imports
import waitress
app = bottle.Bottle()
2)add this as main function
waitress.serve(app, listen='*:44100')
3) change in routes "#bottle" to "#app"
Related
When I try to use the functionality that uses websockets in my application, I get this error in the console:
File "/Users/user/venv/lib/python3.7/site-packages/simple_websocket/ws.py", line 138, in __init__
raise RuntimeError('Cannot obtain socket from WSGI environment.')
RuntimeError: Cannot obtain socket from WSGI environment.
I also get this error in the browser console:
WebSocket connection to 'ws://localhost:5000/socket.io/?EIO=4&transport=websocket&sid=40NYzDgGYStMR0CEAAAJ' failed:
I tried using gevent, gevent-websocket, and eventlet, but this created other issues, and I'm not sure that I need to use gevent or eventlet for this use case.
Here's the rest of the relevant code:
__ init __.py
from flask_socketio import SocketIO
...
socketio = SocketIO()
def create_app(config_class=Config):
app = Flask(__name__)
app.config.from_object(Config)
socketio.init_app(app, cors_allowed_origins='*')
...
return app
app.py
from app import create_app, socketio
app = create_app()
if __name__ == '__main__':
socketio.run(app)
routes.py
This only accepts POST requests because I send data to this route from a Celery task
from app import socketio
...
#main_bp.route('/send_message', methods=['POST'])
def send_message():
...
socketio.emit('test_message', {'msg':'Test'}, namespace='/test')
return 'Results Sent'
index.html
var socket = io.connect('http://localhost:5000/test');
socket.on('connect', function(){
console.log('Connected to socket')
});
socket.on('test_message', function(message){
console.log('Received test message');
}
)
Note that in the browser console I'll see "Connected to socket", but not "Received test message"
You are using the simple-websocket package. This package has a list of supported web servers. The error indicates that you are using a web server that is not in the supported list.
Supported web servers are:
The Flask dev server (for development purposes only, of course)
Gunicorn
Eventlet
Gevent
From this list, it seems your only choice for a production web server is Gunicorn, since you say that eventlet/gevent won't work for your needs.
The use of Gunicorn is covered in the documentation. In that section, simple-websocket is the third option mentioned. Here is the example start up command:
gunicorn -w 1 --threads 100 module:app
Maybe you can turn on the logger and the engine.io logger. that qould give you an idea what is the issue.
don't use eventlet and gevent together. use anyone and uninstall the other.
The following scenario:
I have a Raspberry Pi running as a server. Currently I am using a Python script with Flask and I can also access the Raspberry Pi from my PC. (The flask server runs an react app.)
But the function should be extended. It should look like the following:
2nd Python script is running all the time. This Python script fetches data from an external API every second and processes it. If certain conditions are met, the data should be processed and then the data should be communicated to the Python Flask server. And the Flask server then forwards the data to the website running on the computer.
How or which method is best to program this "interprocess communication". Are there any libraries? I tried Celery, but then it throws up my second Python script whenever I want to access the external API, so I don't know if this is the right choice.
What else would be the best approach? Threading? Direct interprocess communication?
If important, this is how my server application looks so far:
from gevent import monkey
from flask import Flask, render_template
from flask_socketio import SocketIO
monkey.patch_all()
app = Flask(__name__, template_folder='./build', static_folder='./build/static')
socket_io = SocketIO(app)
#app.route('/')
def main():
return render_template('index.html')
#socket_io.on('fromFrontend')
def handleInput(input):
print('Input from Frontend: ' + input)
send_time()
#socket_io.on('time')
def send_time():
socket_io.emit('time', {'returnTime': "some time"})
if __name__ == '__main__':
socket_io.run(app, host='0.0.0.0', port=5000, debug=True)
Well i found a solution for my specific problem i implemented it with a thread as follows:
import gevent.monkey
gevent.monkey.patch_all()
from flask import Flask, render_template
from flask_socketio import SocketIO
import time
import requests
from threading import Thread
app = Flask(__name__, template_folder='./build', static_folder='./build/static')
socket_io = SocketIO(app)
#app.route('/')
def main():
thread = Thread(target=backgroundTask)
thread.daemon = True
thread.start()
return render_template('index.html')
#socket_io.on('fromFrontend')
def handleInput(input):
print('Input from Frontend: ' + input)
#socket_io.on('time')
def send_time():
socket_io.emit('time', {'returnTime': 'hi frontend'})
def backgroundTask():
# do something here
# access socket to push some data
socket_io.emit('time', {'returnTime': "some time"})
if __name__ == '__main__':
socket_io.run(app, host='0.0.0.0', port=5000, debug=True)
I'm trying to create a python Flask REST web API. Since Flask development server is not suitable for production, I tried to use cherrypy application server.
Following is the Flask app I tried to expose via cherrypy
from flask import Flask,request
from flask_restful import Api,Resource, reqparse
app= Flask(__name__)
api = Api(app)
class Main (Resource):
def get(self):
return "Hello Flask"
if __name__ == '__main__':
api.add_resource(Main, "/testapp/")
app.run(debug=True)
Following is the cherrypy script I have created
try:
from cheroot.wsgi import Server as WSGIServer, PathInfoDispatcher
except ImportError:
from cherrypy.wsgiserver import CherryPyWSGIServer as WSGIServer, WSGIPathInfoDispatcher as PathInfoDispatcher
from stack import app
d = PathInfoDispatcher({'/': app})
server = WSGIServer(('127.0.0.1', 8080), d)
if __name__ == '__main__':
try:
server.start()
print("started")
except KeyboardInterrupt:
server.stop()
I have saved this script as "run.py" in my project directory. When I run this it doesn't show any error, which made me to thin this is correct.
But unfortunately I cant access this using the url
Theoretically, url for this API should be some thing like follow
http://127.0.0.1:8080/testapp/
But it throws 404 with the message
"The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again."
What am I doing wrong ?
The
api.add_resource(Main, "/testapp/")
in your file stack.py is not executed if the file is included from your run.py
as the condition
if __name__ == '__main__':
...
is not true (in the context of stack.py).
Moving the call to api.add_resource(...) to a position outside the if-main-condition (so it is always executed) should solve the issue.
I was trying to deploy my Flask app on CherryPy server. I liked its simplistic and minimalistic nature.
So I PIP'ed CherryPy like below
pip install CherryPy-15.0.0-py2.py3-none-any.whl
and wrote script like below -very common suggested by many sources
from cherrypy import wsgiserver
from hello import app
d = wsgiserver.WSGIPathInfoDispatcher({'/': app})
server = wsgiserver.CherryPyWSGIServer(('0.0.0.0', 80), d)
if __name__ == '__main__':
try:
server.start()
except KeyboardInterrupt:
server.stop()
To my surprise, I had imports errors. After a few googling around, I learned that I had to change my import lines to cheroot to make it work.
from cheroot.wsgi import Server
from cheroot.wsgi import PathInfoDispatcher
Now, my code is working fine.
However, I am a bit confused if this is the right way of using CherryPy WSGI server or if I pip'ed a wrong version of CherryPy. I am confused because Cheroot seems to be more than year old (dates all the way back to 2014), yet all the information I found around Flask on CherryPy WSGI server is using from cherrypy import wsgiserver, not from cheroot.wsgi import Server, even the latest postings.
This makes me unsure if I am doing the right thing or not.
Can someone please shed light on this confusion?
Cheroot (src) is a low-level HTTP and WSGI server, which used to be a part of CherryPy (src) once, but has been factored out into a separate repo a while back. So former cherrypy.wsgiserver has moved to cheroot.wsgi module.
It's completely replaceable and designed to allow developers to depend on Cheroot directly if they only use WSGI server, not requiring other parts of CherryPy.
So here's how you can use it in a version-agnostic way:
try:
from cheroot.wsgi import Server as WSGIServer, PathInfoDispatcher
except ImportError:
from cherrypy.wsgiserver import CherryPyWSGIServer as WSGIServer, WSGIPathInfoDispatcher as PathInfoDispatcher
from hello import app
d = PathInfoDispatcher({'/': app})
server = WSGIServer(('0.0.0.0', 80), d)
if __name__ == '__main__':
try:
server.start()
except KeyboardInterrupt:
server.stop()
I wanna be able to run multiple twisted proxy servers on different directories on the same port simultaneously, and I figured I might use flask.
so here's my code:
from flask import Flask
from twisted.internet import reactor
from twisted.web import proxy, server
app = Flask(__name__)
#app.route('/example')
def index():
site = server.Site(proxy.ReverseProxyResource('www.example.com', 80, ''.encode("utf-8")))
reactor.listenTCP(80, site)
reactor.run()
app.run(port=80, host='My_IP')
But whenever I run this script, I get an Internal Server Error, I'm assuming because when app.run is called on port 80, the reactor.run can't be listening on port 80 as well. I wondering if there is some kind of work around to this, or what it is I'm doing wrong. Any help is greatly appreciated, Thanks!!
You can use the WSGIResource from Twisted istead of a ReverseProxy.
UPDATE: Added a more complex example that sets up a WSGIResource at /my_flask and a ReverseProxy at /example
from flask import Flask
from twisted.internet import reactor
from twisted.web.proxy import ReverseProxyResource
from twisted.web.resource import Resource
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource
app = Flask(__name__)
#app.route('/example')
def index():
return 'My Twisted Flask'
flask_site = WSGIResource(reactor, reactor.getThreadPool(), app)
root = Resource()
root.putChild('my_flask', flask_site)
site_example = ReverseProxyResource('www.example.com', 80, '/')
root.putChild('example', site_example)
reactor.listenTCP(8081, Site(root))
reactor.run()
Try running the above in your localhost and then visiting localhost:8081/my_flask/example or localhost:8081/example
You should give klein a try. It's made and used by most of the twisted core devs. The syntax is very much like flask so you won't have to rewrite much if you already have a working flask app. So something like the following should work:
from twisted.internet import reactor
from twisted.web import proxy, server
from klein import Klein
app = Klein()
#app.route('/example')
def home(request):
site = server.Site(proxy.ReverseProxyResource('www.example.com', 80, ''.encode("utf-8")))
reactor.listenTCP(80, site)
app.run('localhost', 8000) # start the klein app on port 8000 and reactor event loop
Links
Klein Docs
Klein Github
The accepted answer does not cover how to run twisted with Flask, and points to a different framework. The answer with an example no longer works either.
Here are two different examples. The first one is the same as the first answer, but fixed to work on Python 3
from flask import Flask
from twisted.internet import reactor
from twisted.web.proxy import ReverseProxyResource
from twisted.web.resource import Resource
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource
app = Flask(__name__)
#app.route('/example')
def index():
return 'My Twisted Flask'
flask_site = WSGIResource(reactor, reactor.getThreadPool(), app)
root = Resource()
root.putChild(b'my_flask', flask_site)
site_example = ReverseProxyResource('www.example.com', 80, b'/')
root.putChild(b'example', site_example)
reactor.listenTCP(8081, Site(root))
reactor.run()
For this example, run it and open any of these:
localhost:8081/my_flask/example
localhost:8081/example
This other example is recommended, since it sets up two services and provides them through a .tac file to twistd.
Take the base code from here: https://github.com/pika/pika/blob/master/examples/twisted_service.py
"""Modify the bottom of the file to pick the new MultiService"""
# ... all the code from twisted_service.py goes here.
# Scroll to the bottom of the file and
# remove everything below application = service.Application("pikaapplication")
# You should keep the PikaService, PikaProtocol and PikaFactory
# classes, since we need them for this code:
from pika.connection import ConnectionParameters
from pika.credentials import PlainCredentials
from twisted.application import service, strports
from twisted.internet import reactor
from twisted.web.server import Site
from twisted.web.wsgi import WSGIResource
from flask import Flask
# This IServiceCollection will hold Pika and Flask
flask_pika_multiservice = service.MultiService()
# FLASK SERVICE SETUP
app = Flask("demoapp")
#app.route('/')
def hello_world():
return 'Hello, World!'
flask_site = Site(WSGIResource(reactor, reactor.getThreadPool(), app))
# New resources can be added, such as WSGI, or proxies by creating
# a root resource in the place of the flask_site, and adding the
# new resources to the root.
# root = Resource()
# root.putChild(b'my_flask_site', flask_site)
# from twisted.web.proxy import ReverseProxyResource
# site_example = ReverseProxyResource('www.example.com', 80, b'/')
# root.putChild(b'example', site_example)
i = strports.service(f"tcp:8088", flask_site)
i.setServiceParent(flask_pika_multiservice)
# PIKA SERVICE SETUP
ps = PikaService(
ConnectionParameters(
host="localhost",
virtual_host="/",
credentials=PlainCredentials("guest", "guest")))
ps.setServiceParent(flask_pika_multiservice)
# Application setup
application = service.Application('flask_pika')
flask_pika_multiservice.setServiceParent(application)
Now you can run it with:
PYTHONPATH=. twistd -ny twisted_service.py
you can skip the python path if you don't want to import anything from the same path. twisted expects projects to actually be installed, and does not support running them directly from the source folder unless you use that workaround.
This second example establishes two services, on different ports. It's for pika and flask running simultaneously on the same twisted server. The best part is that it shows how to set up flask as a service, that can be part of an IServiceCollection