Fix bug 1236: Retry if leader unit is not obtained

[osm/N2VC.git] / n2vc / libjuju.py

diff --git a/n2vc/libjuju.py b/n2vc/libjuju.py
index 0fa42f8..28474a0 100644 (file)
--- 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"
@@ -1025,16 +1036,21 @@ class Libjuju:
             await self.disconnect_controller(controller)
 
     async def add_k8s(
-        self, name: str, configuration: Configuration, storage_class: str
+        self,
+        name: str,
+        configuration: Configuration,
+        storage_class: str,
+        credential_name: str = None,
     ):
         """
         Add a Kubernetes cloud to the controller
 
         Similar to the `juju add-k8s` command in the CLI
 
-        :param: name:           Name for the K8s cloud
-        :param: configuration:  Kubernetes configuration object
-        :param: storage_class:  Storage Class to use in the cloud
+        :param: name:               Name for the K8s cloud
+        :param: configuration:      Kubernetes configuration object
+        :param: storage_class:      Storage Class to use in the cloud
+        :param: credential_name:    Storage Class to use in the cloud
         """
 
         if not storage_class:
@@ -1062,7 +1078,9 @@ class Libjuju:
             },
         )
 
-        return await self.add_cloud(name, cloud, credential)
+        return await self.add_cloud(
+            name, cloud, credential, credential_name=credential_name
+        )
 
     def get_k8s_cloud_credential(
         self, configuration: Configuration,
@@ -1119,20 +1137,28 @@ class Libjuju:
         return client.CloudCredential(auth_type=auth_type, attrs=attrs,)
 
     async def add_cloud(
-        self, name: str, cloud: Cloud, credential: CloudCredential = None
+        self,
+        name: str,
+        cloud: Cloud,
+        credential: CloudCredential = None,
+        credential_name: str = None,
     ) -> Cloud:
         """
         Add cloud to the controller
 
-        :param: name:   Name of the cloud to be added
-        :param: cloud:  Cloud object
-        :param: credential:   CloudCredentials object for the cloud
+        :param: name:               Name of the cloud to be added
+        :param: cloud:              Cloud object
+        :param: credential:         CloudCredentials object for the cloud
+        :param: credential_name:    Credential name.
+                                    If not defined, cloud of the name will be used.
         """
         controller = await self.get_controller()
         try:
             _ = await controller.add_cloud(name, cloud)
             if credential:
-                await controller.add_credential(name, credential=credential, cloud=name)
+                await controller.add_credential(
+                    credential_name or name, credential=credential, cloud=name
+                )
             # Need to return the object returned by the controller.add_cloud() function
             # I'm returning the original value now until this bug is fixed:
             #   https://github.com/juju/python-libjuju/issues/443
@@ -1151,3 +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