Web server in a separate thread?

mikael

Would someone know of a robust web server implementation running in a separate thread, whenever my app is running?

For the web server, I would be happy with any basic option available in Pythonista; vanilla, bottle, flask, ...

To be considered a "robust implementation", my simple wish list includes:

Logs issues, but stays up and running
(Can be made to) Exit cleanly with the rest of the app
Has been used in some real app for a while

Any pointers?

ccc

One example... https://github.com/cclauss/Pythonista_scene/blob/master/remote_control_scene.py#L39

mikael

@ccc, thank you. Seems simple enough, but I cannot get it to release the socket on exit, causing an error on the next run. Was this not an issue for you, or am I doing something wrong?

dgelessus

FWIW, when I've experimented with servers in Pythonista, I also found that the port would often remain "occupied" after stopping the server using the stop button (i. e. KeyboardInterrupt). This was easily fixed by rerunning the server twice - i. e. the first run would fail due to the port being in use, but the second run would work again. (This was a while ago when I was playing around with Python's built-in HTTP server module, no idea if this still happens in current versions, or if this even applies to your situation.)

My wild guess would be that this is some sort of interaction between the "dirty" shutdown via KeyboardInterrupt, the garbage collector, and how Pythonista's interpreter never fully restarts. The KeyboardInterrupt breaks out of the server's main loop, but doesn't close or delete the socket, which is still referenced (indirectly) from a global variable. Rerunning the script clears or overwrites the global, which eventually deletes the socket, but not quick enough for that script run to reuse the port. On the next run, the port is free again and can be reused. (Again, I just came up with this explanation in my head and didn't really verify it. This may be absolute nonsense.)

mikael

Below is a version of a bottle server that runs in a thread and can be told to shut down cleanly, based on this stackoverflow answer.

#coding: utf-8
from ui import *
import bottle, threading, requests, time

from bottle import Bottle, ServerAdapter

class MyWSGIRefServer(ServerAdapter):
  server = None

  def run(self, handler):
    from wsgiref.simple_server import make_server, WSGIRequestHandler
    if self.quiet:
      class QuietHandler(WSGIRequestHandler):
        def log_request(*args, **kw): pass
      self.options['handler_class'] = QuietHandler
    self.server = make_server(self.host, self.port, handler, **self.options)
    self.server.serve_forever()

  def stop(self):
    self.server.shutdown()
    
app = Bottle()
    
@app.get('/')
def bottle_get_index():
  return "Test OK"

if __name__ == '__main__':
  
  w = WebView()
  w.present('full_screen')
  w.load_html('Loading...')
  
  server = MyWSGIRefServer(port=80)
  
  threading.Thread(group=None, target=app.run, name=None, args=(), kwargs={'server': server, 'quiet': False}).start()
  
  time.sleep(2)
  
  req = requests.get('http://127.0.0.1/')
  w.load_html(req.text)
  
  server.stop()