Adding function to wait for server to be back online after core element upgrade

main.py

@@ -1,5 +1,6 @@
 import os
 import json
+from time import sleep
 
 import requests
 
@@ -75,6 +76,14 @@ class PortainerClient:
 
         return f"Downloaded newer image for {image}" in status
 
+    def ping_server(self):
+        try:
+            r = requests.get(f"{self.api_url}/", headers=self._get_headers())
+        except requests.exceptions.ConnectionError:
+            return False
+
+        return r.status_code == 200
+
 
 def update_repositories():
     for repo_path in config.git_repositories:
@@ -118,6 +127,9 @@ if __name__ == '__main__':
                 print(f"Restarting {stack_name}")
                 if endpoint == 2 and stack_name in ('portainer', 'traefik'):
                     update_local_stack(stack)
+                    while not client.ping_server():
+                        print("Waiting for server to be back online...")
+                        sleep(1)
                 else:
                     client.upgrade_stack(stack)