randomize scraping interval

scrape.py

@@ -4,6 +4,7 @@ import requests
 import re
 from bs4 import BeautifulSoup
 from datetime import datetime, timedelta
+from random import randrange
 
 import asyncio
 from nio import ClientConfig, AsyncClient, LoginResponse, InviteEvent
@@ -171,7 +172,8 @@ async def main():
                                         state_key=category,
                                         content={'url_list': cache})
 
-            next_update = datetime.now() + timedelta(minutes=15)
+            # wait between 15min and 30min to randomize scraping
+            next_update = datetime.now() + timedelta(minutes=randrange(15, 30))
 
 
 homeserver = environ['HOMESERVER']