upgrades: add upgrade paths for octopus

Detail octopus upgrade path and link with Ussuri UCA.

Change-Id: I7dbdc5c265641d4eb561b69f57b8bab41781b698

charms_ceph/utils.py

@@ -2900,6 +2900,7 @@ UPGRADE_PATHS = collections.OrderedDict([
     ('jewel', 'luminous'),
     ('luminous', 'mimic'),
     ('mimic', 'nautilus'),
+    ('nautilus', 'octopus'),
 ])
 
 # Map UCA codenames to ceph codenames
@@ -2916,6 +2917,7 @@ UCA_CODENAME_MAP = {
     'rocky': 'mimic',
     'stein': 'mimic',
     'train': 'nautilus',
+    'ussuri': 'octopus',
 }
 
 

unit_tests/test_utils.py

@@ -946,6 +946,7 @@ class CephTestCase(unittest.TestCase):
             'jewel -> luminous',
             'luminous -> mimic',
             'mimic -> nautilus',
+            'nautilus -> octopus',
         ])
         self.assertEqual(utils.pretty_print_upgrade_paths(), expected)