Fix magmagw: race condition when orch not ready yet

magma/hackfest_magma-agw-enb_vnfd/charms/magmagw/src/charm.py

@@ -173,11 +173,20 @@ class SimpleHAProxyCharm(CharmBase):
             orch_ip = event.params["orch_ip"]
             orch_net = event.params["orch_net"]
             proxy = self.get_ssh_proxy()
-            stdout, stderr = proxy.run(
-                "/home/magma/addnet.py --orch_ip {} --orch_net {}".format(
-                    orch_ip, orch_net
-                )
-            )
+
+            attempt = 0
+            while attempt < 50:
+                try:
+                    stdout, stderr = proxy.run(
+                        "/home/magma/addnet.py --orch_ip {} --orch_net {}".format(
+                            orch_ip, orch_net
+                        )
+                    )
+                    break
+                except subprocess.CalledProcessError:
+                    attempt += 1
+                    import time
+                    time.sleep(5)
             event.set_results({"output": stdout, "stderr": stderr})
         else:
             event.fail("Unit is not leader")