X-Git-Url: https://osm.etsi.org/gitweb/?p=osm%2FN2VC.git;a=blobdiff_plain;f=n2vc%2Flibjuju.py;h=28474a082bd4767f5a897f8d44bc8dbe9f4b6508;hp=a00fa58aaa0bc1b2535bc5aa16707fb59e594f67;hb=59f520da90fb12b9d9871889dfbc5d57aa14c591;hpb=7077e2601a209a87f7fe397b35586e7701ca759a;ds=sidebyside

diff --git a/n2vc/libjuju.py b/n2vc/libjuju.py
index a00fa58..28474a0 100644
--- a/n2vc/libjuju.py
+++ b/n2vc/libjuju.py
@@ -22,6 +22,7 @@ from juju.errors import JujuAPIError
 from juju.model import Model
 from juju.machine import Machine
 from juju.application import Application
+from juju.unit import Unit
 from juju.client._definitions import (
     FullStatus,
     QueryApplicationOffersResults,
@@ -629,11 +630,21 @@ class Libjuju:
             if application is None:
                 raise JujuApplicationNotFound("Cannot execute action")
 
-            # Get unit
+            # Get leader unit
+            # Racing condition:
+            #   Ocassionally, self._get_leader_unit() will return None
+            #   because the leader elected hook has not been triggered yet.
+            #   Therefore, we are doing some retries. If it happens again,
+            #   re-open bug 1236
+            attempts = 3
+            time_between_retries = 10
             unit = None
-            for u in application.units:
-                if await u.is_leader_from_status():
-                    unit = u
+            for _ in range(attempts):
+                unit = await self._get_leader_unit(application)
+                if unit is None:
+                    await asyncio.sleep(time_between_retries)
+                else:
+                    break
             if unit is None:
                 raise JujuLeaderUnitNotFound(
                     "Cannot execute action: leader unit not found"
@@ -1166,3 +1177,11 @@ class Libjuju:
             await controller.remove_cloud(name)
         finally:
             await self.disconnect_controller(controller)
+
+    async def _get_leader_unit(self, application: Application) -> Unit:
+        unit = None
+        for u in application.units:
+            if await u.is_leader_from_status():
+                unit = u
+                break
+        return unit