Handle "no RAM info was set" migration case

This handles the case where the live migration monitoring thread may
race and call jobStats() after the migration has completed resulting in
the following error:

    libvirt.libvirtError: internal error: migration was active, but no
    RAM info was set

Closes-Bug: #1982284
Change-Id: I77fdfa9cffbd44b2889f49f266b2582bcc6a4267
(cherry picked from commit 9fea934)
(cherry picked from commit 00396fa)

Author: brettmilford

nova/tests/unit/virt/libvirt/test_guest.py

@@ -1040,3 +1040,25 @@ def test_job_info_operation_invalid(self, mock_stats, mock_info):
 
         mock_stats.assert_called_once_with()
         mock_info.assert_called_once_with()
+
+    @mock.patch.object(fakelibvirt.virDomain, "jobInfo")
+    @mock.patch.object(fakelibvirt.virDomain, "jobStats")
+    def test_job_stats_no_ram(self, mock_stats, mock_info):
+        mock_stats.side_effect = fakelibvirt.make_libvirtError(
+            fakelibvirt.libvirtError,
+            "internal error: migration was active, but no RAM info was set",
+            error_code=fakelibvirt.VIR_ERR_INTERNAL_ERROR,
+            error_message="migration was active, but no RAM info was set")
+
+        info = self.guest.get_job_info()
+
+        self.assertIsInstance(info, libvirt_guest.JobInfo)
+        self.assertEqual(fakelibvirt.VIR_DOMAIN_JOB_NONE, info.type)
+        self.assertEqual(0, info.time_elapsed)
+        self.assertEqual(0, info.time_remaining)
+        self.assertEqual(0, info.memory_total)
+        self.assertEqual(0, info.memory_processed)
+        self.assertEqual(0, info.memory_remaining)
+
+        mock_stats.assert_called_once_with()
+        self.assertFalse(mock_info.called)

nova/virt/libvirt/guest.py

@@ -655,6 +655,7 @@ def get_job_info(self):
                 stats = self._domain.jobStats()
                 return JobInfo(**stats)
             except libvirt.libvirtError as ex:
+                errmsg = ex.get_error_message()
                 if ex.get_error_code() == libvirt.VIR_ERR_NO_SUPPORT:
                     # Remote libvirt doesn't support new API
                     LOG.debug("Missing remote virDomainGetJobStats: %s", ex)
@@ -667,6 +668,12 @@ def get_job_info(self):
                     # away completclsely
                     LOG.debug("Domain has shutdown/gone away: %s", ex)
                     return JobInfo(type=libvirt.VIR_DOMAIN_JOB_COMPLETED)
+                elif (ex.get_error_code() == libvirt.VIR_ERR_INTERNAL_ERROR and
+                      errmsg and "migration was active, "
+                      "but no RAM info was set" in errmsg):
+                    LOG.debug("Migration is active or completed but "
+                              "virDomainGetJobStats is missing ram: %s", ex)
+                    return JobInfo(type=libvirt.VIR_DOMAIN_JOB_NONE)
                 else:
                     LOG.debug("Failed to get job stats: %s", ex)
                     raise

releasenotes/notes/bug-1982284-libvirt-handle-no-ram-info-was-set-99784934ed80fd72.yaml

@@ -0,0 +1,11 @@
+---
+other:
+  - |
+    A workaround has been added to the libvirt driver to catch and pass
+    migrations that were previously failing with the error:
+
+    ``libvirt.libvirtError: internal error: migration was active, but no RAM info was set``
+
+    See `bug 1982284`_ for more details.
+
+    .. _bug 1982284: https://bugs.launchpad.net/nova/+bug/1982284