Starting and stopping Google App Engine backends

Question

I read the Google App Engine backend docs, but I still can\'t understand how to start/stop backends (dynamic backends) from Python (using URLFetch, I guess).

Could s

Answer 1

It depends on what type of backend you are using, "Resident Backends" can't be shutdown from the production environment only via the Admin Console or command-line while "Dynamic Backends" are shutdown after sitting idle for a few minutes.

So if you use Dynamic Backends you can just send a request telling it to stop what it is doing and it will be shutdown automatically.

http://code.google.com/intl/iw/appengine/docs/python/config/backends.html#Types_of_Backends

Edit

Example of how this might work:

from google.appengine.ext import webapp
from google.appengine.api import memcache
from google.appengine.ext.webapp.util import run_wsgi_app
import time

class ShutdownHandler(webapp.RequestHandler):
    def get(self):
        memcache.put('backendShutdown', True, 60)

class StartHandler(webapp.RequestHandler):
    def get(self):
        lastCheck = time.time()
        while True:
            if time.time() - 60 > lastCheck:
                stopBackend = memcache.get('backendShutdown')
                if stopBackend:
                    memcache.delete('backendShutdown')
                    break
                lastCheck = time.time()


if __name__ == '__main__':
    _handlers = [(r'/_ah/start', StartHandler),
                 (r'/backend/worker/shutdown', ShutdownHandler)] # somekind of handler for shutdown
    run_wsgi_app(webapp.WSGIApplication(_handlers))

And to stop it you would use:

from google.appengine.api import backends, urlfetch
url = backends.get_url('worker') + '/backend/worker/shutdown'
urlfetch.fetch(url)