Warn in status if tune-osd-memory-target invalid

This is useful, because if an invalid value is set,
the value is ignored and not overridden,
and an error logged.
So now we warn about this in the status to be more obvious to the user.

Change-Id: Idc4a7706f30cbcea8aee83a1406fa84139fe510d

hooks/ceph_hooks.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 
 import base64
+from enum import Enum
 import glob
 import json
 import netifaces
@@ -25,6 +26,7 @@ import socket
 import subprocess
 import sys
 import traceback
+from typing import NamedTuple
 
 sys.path.append('lib')
 import charms_ceph.utils as ceph
@@ -386,7 +388,21 @@ def warn_if_memory_outside_bounds(value):
             "This is not recommended.", level=WARNING)
 
 
-def get_osd_memory_target():
+class OSDMemoryTargetType(Enum):
+    EMPTY = 1
+    GB = 2
+    PERCENT = 3
+    INVALID = 4
+
+
+class OSDMemoryTarget(NamedTuple):
+    # the value in bytes, as a string
+    value: str
+    # the original parsed type from the tune-osd-memory-target config value
+    parsed_type: OSDMemoryTargetType
+
+
+def get_osd_memory_target() -> OSDMemoryTarget:
     """
     Processes the config value of tune-osd-memory-target.
 
@@ -398,13 +414,16 @@ def get_osd_memory_target():
     tune_osd_memory_target = config('tune-osd-memory-target')
 
     if not tune_osd_memory_target:
-        return ""
+        return OSDMemoryTarget(value="", parsed_type=OSDMemoryTargetType.EMPTY)
 
     match = re.match(r"(\d+)GB$", tune_osd_memory_target)
     if match:
         osd_memory_target = int(match.group(1)) * 1024 * 1024 * 1024
         warn_if_memory_outside_bounds(osd_memory_target)
-        return str(osd_memory_target)
+        return OSDMemoryTarget(
+            value=str(osd_memory_target),
+            parsed_type=OSDMemoryTargetType.GB
+        )
 
     match = re.match(r"(\d+)%$", tune_osd_memory_target)
     if match:
@@ -412,11 +431,14 @@ def get_osd_memory_target():
         num_osds = len(kv().get("osd-devices", []))
         osd_memory_target = int(get_total_ram() * percentage / num_osds)
         warn_if_memory_outside_bounds(osd_memory_target)
-        return str(osd_memory_target)
+        return OSDMemoryTarget(
+            value=str(osd_memory_target),
+            parsed_type=OSDMemoryTargetType.PERCENT
+        )
 
     log("tune-osd-memory-target value invalid,"
         " leaving the OSD memory target unchanged", level=ERROR)
-    return ""
+    return OSDMemoryTarget(value="", parsed_type=OSDMemoryTargetType.INVALID)
 
 
 def get_ceph_context(upgrading=False):
@@ -539,7 +561,7 @@ def config_changed():
             relation_id=r_id,
             relation_settings={
                 'osd-host': socket.gethostname(),
-                'osd-memory-target': get_osd_memory_target(),
+                'osd-memory-target': get_osd_memory_target().value,
             }
         )
 
@@ -633,7 +655,7 @@ def prepare_disks_and_activate():
                     hookenv.config('source') or 'distro'
                 ),
                 'osd-host': socket.gethostname(),
-                'osd-memory-target': get_osd_memory_target(),
+                'osd-memory-target': get_osd_memory_target().value,
             }
         )
 
@@ -869,6 +891,11 @@ VERSION_PACKAGE = 'ceph-common'
 def assess_status():
     """Assess status of current unit"""
     # check to see if the unit is paused.
+
+    if get_osd_memory_target().parsed_type == OSDMemoryTargetType.INVALID:
+        status_set('blocked', 'tune-osd-memory-target config value is invalid')
+        return
+
     application_version_set(get_upstream_version(VERSION_PACKAGE))
     if is_unit_upgrading_set():
         status_set("blocked",

unit_tests/test_ceph_hooks.py

@@ -755,7 +755,8 @@ class CephHooksTestCase(unittest.TestCase):
         mock_config.side_effect = config_func
 
         target = ceph_hooks.get_osd_memory_target()
-        self.assertEqual(target, str(5 * 1024 * 1024 * 1024))  # 5GB
+        self.assertEqual(target.value, str(5 * 1024 * 1024 * 1024))  # 5GB
+        self.assertEqual(target.parsed_type, ceph_hooks.OSDMemoryTargetType.GB)
 
     @patch.object(ceph_hooks, "config")
     @patch.object(ceph_hooks, "get_total_ram")
@@ -776,7 +777,11 @@ class CephHooksTestCase(unittest.TestCase):
 
         target = ceph_hooks.get_osd_memory_target()
         # should be 50% of 16GB / 2 osd devices = 4GB
-        self.assertEqual(target, str(4 * 1024 * 1024 * 1024))  # 4GB
+        self.assertEqual(target.value, str(4 * 1024 * 1024 * 1024))  # 4GB
+        self.assertEqual(
+            target.parsed_type,
+            ceph_hooks.OSDMemoryTargetType.PERCENT
+        )
 
     @patch.object(ceph_hooks, "config")
     @patch.object(ceph_hooks, "get_total_ram")
@@ -792,7 +797,11 @@ class CephHooksTestCase(unittest.TestCase):
         mock_config.side_effect = lambda _: None
 
         target = ceph_hooks.get_osd_memory_target()
-        self.assertEqual(target, "")
+        self.assertEqual(target.value, "")
+        self.assertEqual(
+            target.parsed_type,
+            ceph_hooks.OSDMemoryTargetType.EMPTY
+        )
 
     @patch.object(ceph_hooks, "config")
     @patch.object(ceph_hooks, "get_total_ram")
@@ -812,7 +821,11 @@ class CephHooksTestCase(unittest.TestCase):
         mock_config.side_effect = config_func
 
         target = ceph_hooks.get_osd_memory_target()
-        self.assertEqual(target, "")
+        self.assertEqual(target.value, "")
+        self.assertEqual(
+            target.parsed_type,
+            ceph_hooks.OSDMemoryTargetType.INVALID
+        )
         mock_log.assert_called_with(
             "tune-osd-memory-target value invalid,"
             " leaving the OSD memory target unchanged",