dist upgrade before series upgrade

unit_tests/utilities/test_zaza_utilities_generic.py

@@ -166,6 +166,17 @@ def test_get_yaml_config(self):
                          _yaml_dict)
         self._open.assert_called_once_with(_filename, "r")
 
+    def test_dist_upgrade(self):
+        _unit = "app/2"
+        generic_utils.dist_upgrade(_unit)
+        dist_upgrade_cmd = (
+            """sudo DEBIAN_FRONTEND=noninteractive apt --assume-yes """
+            """-o "Dpkg::Options::=--force-confdef" """
+            """-o "Dpkg::Options::=--force-confold" dist-upgrade""")
+        self.model.run_on_unit.assert_has_calls([
+            mock.call(_unit, 'sudo apt update'),
+            mock.call(_unit, dist_upgrade_cmd)])
+
     def test_do_release_upgrade(self):
         _unit = "app/2"
         generic_utils.do_release_upgrade(_unit)

zaza/openstack/utilities/generic.py

@@ -374,6 +374,7 @@ def series_upgrade(unit_name, machine_num,
     model.block_until_unit_wl_status(unit_name, "blocked")
     logging.info("Waiting for model idleness")
     model.block_until_all_units_idle()
+    dist_upgrade(unit_name)
     wrap_do_release_upgrade(unit_name, from_series=from_series,
                             to_series=to_series, files=files,
                             workaround_script=workaround_script)
@@ -481,6 +482,26 @@ def run_via_ssh(unit_name, cmd):
         logging.warn(e)
 
 
+def dist_upgrade(unit_name):
+    """Run dist-upgrade on unit after update package db.
+
+    :param unit_name: Unit Name
+    :type unit_name: str
+    :returns: None
+    :rtype: None
+    """
+    logging.info('Updating package db ' + unit_name)
+    update_cmd = 'sudo apt update'
+    model.run_on_unit(unit_name, update_cmd)
+
+    logging.info('Updating existing packages ' + unit_name)
+    dist_upgrade_cmd = (
+        """sudo DEBIAN_FRONTEND=noninteractive apt --assume-yes """
+        """-o "Dpkg::Options::=--force-confdef" """
+        """-o "Dpkg::Options::=--force-confold" dist-upgrade""")
+    model.run_on_unit(unit_name, dist_upgrade_cmd)
+
+
 def do_release_upgrade(unit_name):
     """Run do-release-upgrade noninteractive.