Merge "Catch error and log warning when not able to update mtimes"

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

@@ -724,3 +724,10 @@ disk size: 4.4M
             {'properties': {'architecture': "X86_64"}})
         image_arch = libvirt_utils.get_arch(image_meta)
         self.assertEqual(arch.X86_64, image_arch)
+
+    def test_update_mtime_error(self):
+        with mock.patch.object(libvirt_utils, 'execute',
+                               side_effect=processutils.ProcessExecutionError):
+            with mock.patch.object(libvirt_utils.LOG, 'warning') as mock_log:
+                libvirt_utils.update_mtime(mock.sentinel.path)
+        self.assertTrue(mock_log.called)

nova/virt/libvirt/utils.py

@@ -31,6 +31,7 @@ from nova.compute import vm_mode
 import nova.conf
 from nova.i18n import _
 from nova.i18n import _LI
+from nova.i18n import _LW
 from nova import utils
 from nova.virt import images
 from nova.virt.libvirt import config as vconfig
@@ -245,7 +246,16 @@ def update_mtime(path):
 
     :param path: File bump the mtime on
     """
-    execute('touch', '-c', path, run_as_root=True)
+    try:
+        execute('touch', '-c', path, run_as_root=True)
+    except processutils.ProcessExecutionError as exc:
+        # touch can intermittently fail when launching several instances with
+        # the same base image and using shared storage, so log the exception
+        # but don't fail. Ideally we'd know if we were on shared storage and
+        # would re-raise the error if we are not on shared storage.
+        LOG.warning(_LW("Failed to update mtime on path %(path)s. "
+                        "Error: %(error)s"),
+                    {'path': path, "error": exc})
 
 
 def _id_map_to_config(id_map):