Merge ~ack/maas:1988759-vmhost-deploy-3.1 into maas:3.1

[Alberto Donato]

LP:1988759 allow null config from LXD storage pools

(backport of 95c09efaf and 9b23293a6)

[Alberto Donato (ack)]

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b 1988759-vmhost-deploy-3.1 lp:~ack/maas/+git/maas into -b 3.1 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/1072/consoleText

[MAAS Lander (maas-lander)]

LANDING
-b 1988759-vmhost-deploy-3.1 lp:~ack/maas/+git/maas into -b 3.1 lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/1074/consoleText

diff --git a/src/provisioningserver/drivers/pod/lxd.py b/src/provisioningserver/drivers/pod/lxd.py
index 2ef7f8c..0706aee 100644
--- a/src/provisioningserver/drivers/pod/lxd.py
+++ b/src/provisioningserver/drivers/pod/lxd.py
@@ -391,7 +391,7 @@ class LXDPodDriver(PodDriver):
         pools = []
         local_storage = 0
         for storage_pool in storage_pools:
-            discovered_storage_pool = self._get_discovered_pod_storage_pool(
+            discovered_storage_pool = self._get_discovered_storage_pool(
                 storage_pool
             )
             local_storage += discovered_storage_pool.storage
@@ -803,11 +803,12 @@ class LXDPodDriver(PodDriver):
             location=machine.location,
         )
 
-    def _get_discovered_pod_storage_pool(self, storage_pool):
-        """Get the Pod storage pool."""
-        storage_pool_config = storage_pool.config
-        # Sometimes the config is empty, use get() method on the dictionary in case.
-        storage_pool_path = storage_pool_config.get("source")
+    def _get_discovered_storage_pool(self, storage_pool):
+        """Get storage pool info by name."""
+        # Storage configuration can either be empty or None (if credentials are
+        # restricted to a project)
+        storage_pool_config = storage_pool.config or {}
+        storage_pool_path = storage_pool_config.get("source", "")
         storage_pool_resources = storage_pool.resources.get()
         total_storage = storage_pool_resources.space["total"]
 
@@ -875,7 +876,7 @@ class LXDPodDriver(PodDriver):
                 try:
                     client.authenticate(password)
                 except LXDAPIException as e:
-                    raise Error(f"Password authentication failed: {e}")
+                    raise Error(f"Password authentication failed: {e}") from e
             return client
 
         try:
@@ -898,10 +899,10 @@ class LXDPodDriver(PodDriver):
                 raise Error(
                     "Certificate is not trusted and no password was given"
                 )
-        except ClientConnectionFailed:
+        except ClientConnectionFailed as e:
             raise LXDPodError(
-                f"Pod {pod_id}: Failed to connect to the LXD REST API."
-            )
+                f"Pod {pod_id}: Failed to connect to the LXD REST API: {e}"
+            ) from e
         yield client
         if cert_paths:
             for path in cert_paths:
diff --git a/src/provisioningserver/drivers/pod/tests/test_lxd.py b/src/provisioningserver/drivers/pod/tests/test_lxd.py
index c74af1f..d72ec1d 100644
--- a/src/provisioningserver/drivers/pod/tests/test_lxd.py
+++ b/src/provisioningserver/drivers/pod/tests/test_lxd.py
@@ -721,12 +721,11 @@ class TestLXDPodDriver(MAASTestCase):
             ],
         )
 
-    def test_get_discovered_pod_storage_pool(self):
+    def test_get_discovered_storage_pool(self):
         mock_storage_pool = Mock()
         mock_storage_pool.name = factory.make_name("pool")
         mock_storage_pool.driver = "dir"
         mock_storage_pool.config = {
-            "size": "61203283968",
             "source": "/home/chb/mnt/l2/disks/default.img",
             "volume.size": "0",
             "zfs.pool_name": "default",
@@ -734,8 +733,8 @@ class TestLXDPodDriver(MAASTestCase):
         mock_resources = Mock()
         mock_resources.space = {"used": 207111192576, "total": 306027577344}
         mock_storage_pool.resources.get.return_value = mock_resources
-        discovered_pod_storage_pool = (
-            self.driver._get_discovered_pod_storage_pool(mock_storage_pool)
+        discovered_pod_storage_pool = self.driver._get_discovered_storage_pool(
+            mock_storage_pool
         )
         self.assertEqual(
             mock_storage_pool.name, discovered_pod_storage_pool.id
@@ -754,6 +753,35 @@ class TestLXDPodDriver(MAASTestCase):
             mock_resources.space["total"], discovered_pod_storage_pool.storage
         )
 
+    def test_get_discovered_storage_pool_no_source(self):
+        mock_storage_pool = Mock()
+        mock_storage_pool.name = factory.make_name("pool")
+        mock_storage_pool.driver = "dir"
+        mock_storage_pool.config = {
+            "volume.size": "0",
+            "zfs.pool_name": "default",
+        }
+        mock_resources = Mock()
+        mock_resources.space = {"used": 207111192576, "total": 306027577344}
+        mock_storage_pool.resources.get.return_value = mock_resources
+        discovered_pod_storage_pool = self.driver._get_discovered_storage_pool(
+            mock_storage_pool
+        )
+        self.assertEqual(discovered_pod_storage_pool.path, "")
+
+    def test_get_discovered_storage_pool_no_config(self):
+        mock_storage_pool = Mock()
+        mock_storage_pool.name = factory.make_name("pool")
+        mock_storage_pool.driver = "dir"
+        mock_storage_pool.config = None
+        mock_resources = Mock()
+        mock_resources.space = {"used": 207111192576, "total": 306027577344}
+        mock_storage_pool.resources.get.return_value = mock_resources
+        discovered_pod_storage_pool = self.driver._get_discovered_storage_pool(
+            mock_storage_pool
+        )
+        self.assertEqual(discovered_pod_storage_pool.path, "")
+
     def test_get_discovered_machine(self):
         mock_machine = Mock()
         mock_machine.name = factory.make_name("machine")