I wanted Flask to run continuously. I tried the proposed solution to run them together as threads as suggested by @amanb. I found out Flask is blocking Kivy and vice versa no matter the timing or how arranged are the threads. The reason being the interpreter's GIL. Therefore I tried with processes and it seems it does the work.
CODE
#!/usr/bin/python2.7 python2.7
# -*- coding: utf-8 -*-
# kivy modules first, if not Kivy may cause problems
import kivy
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.label import Label
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.screenmanager import ScreenManager, Screen
kivy.require('1.10.0')
# common modules
import sys
import signal
from multiprocessing import Process
# Flask & similar modules
from flask import Flask
from flask_restful import reqparse, abort, Api, Resource
import eventlet
from eventlet import wsgi
# async server setup
app = Flask(__name__)
api = Api(app)
def start_Flask():
print("Starting server...")
# start an eventlet WSGI server on port 5000
wsgi.server(eventlet.listen(('', 5000)), app)
def signal_handler(signal, frame):
# for fetching CTRL+C and relatives
print " CTRL + C detected, exiting ... "
exit(1)
# Kivy screen class
class MainScreen(Screen):
def __init__(self, **kwargs):
self.name="MAIN SCREEN"
super(Screen, self).__init__(**kwargs)
# Kivy app class
class Kivy(App):
w_MessageBox10_1 = "MAIN SCREEN"
w_MessageBox10_2 = "One golden glance of what should be"
w_MessageBox30_2 = "CHORUS"
w_MessageBox30_3 = "EXIT"
# exit button action
def exit(self):
print "exiting... one shaft of light will show the way..."
p1.terminate() # terminate Flask by pressing on cancel
exit(1)
# do magic button action
def do_magic(self):
# your code goes here or maybe not
print "***** it's a kind of magic *************************"
# Kivy UI builder file
def build(self):
sm = Builder.load_string("""
ScreenManager
MainScreen:
size_hint: 1, .7
auto_dismiss: False
title: app.w_MessageBox10_1
title_align: "center"
BoxLayout:
orientation: "vertical"
Label:
text: app.w_MessageBox10_2
BoxLayout:
orientation: "horizontal"
spacing: 10
size_hint: 1, .5
Button:
text: app.w_MessageBox30_2 # DO MAGIC
on_press:
app.do_magic()
Button:
text: app.w_MessageBox30_3 # EXIT
on_press:
app.exit()
""")
return sm
if __name__ == '__main__':
# #CTRL+C signal handler
signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)
global p1
p1 = Process(target=start_Flask) # assign Flask to a process
p1.start() # run Flask as process
Kivy().run() # run Kivy UI
UPDATE
To run Flask on demand by pressing a button in Kivy I use the script below.
#!/usr/bin/python2.7 python2.7
# -*- coding: utf-8 -*-
# kivy modules first, if not Kivy may cause problems
import kivy
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.label import Label
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.screenmanager import ScreenManager, Screen
kivy.require('1.10.0')
# common modules
import sys
import os
import time
import signal
from multiprocessing import Process
# Flask modules
from flask import Flask
# wsgi (Web Server Gateway Interface) modules
import eventlet
from eventlet import wsgi
# async server setup
app = Flask(__name__)
def signal_handler(signal, frame):
print " CTRL + C detected, exiting ... "
exit(0)
# kivy gui classes ######################################################
class MainScreen(Screen):
def __init__(self, **kwargs):
self.name="MAIN SCREEN"
super(Screen, self).__init__(**kwargs)
class MainApp(App):
MainScreenTitle = "MainScreen title"
MainScreenLabel = "MainScreen label"
MessageButtonEnter = "START"
MessageButtonExit = "EXIT"
def start_Flask(self):
print("Starting Flask...")
wsgi.server(eventlet.listen(('', 5000)), app) # deploy as an eventlet WSGI server
def stop(self):
print "terminating Flask and exiting..."
global p1
p1.terminate()
exit(1)
def start(self):
print "starting Flask as process..."
global p1
p1 = Process(target=self.start_Flask) # assign Flask to a process
p1.daemon = True
p1.start() #launch Flask as separate process
def build(self):
sm = Builder.load_string("""
ScreenManager
MainScreen:
size_hint: 1, .7
auto_dismiss: False
title: app.MainScreenTitle
title_align: "center"
BoxLayout:
orientation: "vertical"
Label:
text: app.MainScreenLabel
BoxLayout:
orientation: "horizontal"
spacing: 10
size_hint: 1, .5
Button:
text: app.MessageButtonEnter # start app
on_press:
app.start()
Button:
text: app.MessageButtonExit # exit app
on_press:
app.stop()
""")
return sm
# main ################################################
if __name__ == '__main__':
#CTRL+C signal handler
signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)
MainApp().run() # run Kivy app
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