500 error while deploying telegram bot to google app engine - google-app-engine

Question

I'm new to telegram bot development, and I got stuck, while deploying project to GAE and creating webhooks
I have a simple bot, which I took from here https://github.com/sooyhwang/Simple-Echo-Telegram-Bot:
from flask import Flask, request
import telegram
import config
import logging
bot = telegram.Bot(config.token)
app = Flask(__name__)
URL = 'my-service-dot-kristik-160312.appspot.com/'
#def sendPhotoToServer() -> Bool:
# sending photo to server
# return
#app.route('/HOOK', methods=['POST'])
def webhook_handler():
if request.method == "POST":
update = telegram.Update.de_json(request.get_json(force=True))
chat_id = update.message.chat.id
text = update.message.text.encode('utf-8')
bot.sendMessage(chat_id=chat_id, text=text)
logging.getLogger().setLevel(logging.INFO)
logging.info('===============TEXT=================')
return 'ok'
#app.route('/set_webhook', methods=['GET', 'POST'])
def set_webhook():
s = bot.setWebhook('https://my-service-dot-kristik-160312.appspot.com/HOOK')
if s:
return "webhook setup ok"
else:
return "webhook setup failed"
#app.route('/')
def index():
return 'App is ready'
When I go to https://my-service-dot-kristik-160312.appspot.com/set_webhook I get 500 error.
What am I doing wrong?
Server logs:
5.254.65.88 - - [04/Mar/2017:00:53:54 +0300] "GET /set_webhook HTTP/1.1" 500 264 - "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36" "my-service-dot-kristik-160312.appspot.com" ms=12 cpu_ms=18 cpm_usd=2.9504e-8 loading_request=0 instance=00c61b117c22a1c62e3fac7b35862e68e42b61f0284c2de4c4f50e319bcfa0d57efafc3b4e58 app_engine_release=1.9.48 trace_id=28ae78361cb2dde6bf4f6388ba535198
00:53:54.036
Entering: setWebhook
00:53:54.040
[2017-03-03 21:53:54,039] ERROR in app: Exception on /set_webhook [GET]
00:53:54.040
Traceback (most recent call last):
00:53:54.040
File "/base/data/home/apps/e~kristik-160312/my-service:20170303t195857.399582377782761728/lib/flask/app.py", line 1982, in wsgi_app
00:53:54.040
response = self.full_dispatch_request()
00:53:54.040
File "/base/data/home/apps/e~kristik-160312/my-service:20170303t195857.399582377782761728/lib/flask/app.py", line 1614, in full_dispatch_request
00:53:54.040
rv = self.handle_user_exception(e)
00:53:54.040
File "/base/data/home/apps/e~kristik-160312/my-service:20170303t195857.399582377782761728/lib/flask/app.py", line 1517, in handle_user_exception
00:53:54.040
reraise(exc_type, exc_value, tb)
00:53:54.040
File "/base/data/home/apps/e~kristik-160312/my-service:20170303t195857.399582377782761728/lib/flask/app.py", line 1612, in full_dispatch_request

Answer 1

Telegram Bot API Webhooks are not made to support redirections.
When you set the Webhook URL as the GAE, nothing works. Upon checking getWebhooInfo, you will get the last_error_message as Wrong response from the webhook: 302 Moved Temporarily
And yes, Google Script Content Service documentation says, content returned by the Content service isn't served from script.google.com, but instead redirected to a one-time URL at script.googleusercontent.com. This means that if you use the Content service to return data to another application, you must ensure that the HTTP client is configured to follow redirects
So, you cannot use Google Script URL as webhook