fix: Keep the override flags in the all flags state when the store cannot list its flags

When the store's all-items read fails, the client logs the failure as
before and, if the override layer holds flags, returns a state of those
flags marked invalid instead of an empty one. Overrides only add to the
state, and a client-side SDK bootstrapped from it uses its flags whatever
$valid says, so the overridden values still reach it. With no override
flags the state is the same invalid, empty state as without a source.

Author: kinyoklion

ldclient/async_client.py

@@ -608,7 +608,7 @@ async def all_flags_state(self, context: Context, **kwargs) -> FeatureFlagsState
             log.warning("Context was invalid for all_flags_state (%s); returning default value" % context.error)
             return FeatureFlagsState(False)
 
-        state = FeatureFlagsState(True)
+        valid = True
         client_only = kwargs.get('client_side_only', False)
         with_reasons = kwargs.get('with_reasons', False)
         details_only_if_tracked = kwargs.get('details_only_for_tracked_flags', False)
@@ -624,8 +624,18 @@ async def all_flags_state(self, context: Context, **kwargs) -> FeatureFlagsState
                     raise ValueError("feature store error")
             except Exception as e:
                 log.error("Unable to read flags for all_flag_state: %s" % repr(e))
-                return FeatureFlagsState(False)
+                # Overrides only add to the state. Without them the state is invalid and empty
+                # here, so it holds the override layer's flags and stays invalid. A client-side
+                # SDK bootstrapped from the state uses its flags whatever $valid says (the
+                # JavaScript client SDKs 3.x and 4.x only warn), so the overridden values still
+                # reach it.
+                layer = self._data_system.override_layer
+                flags_map = layer.all(FEATURES) if layer is not None else {}
+                if len(flags_map) == 0:
+                    return FeatureFlagsState(False)
+                valid = False
 
+        state = FeatureFlagsState(valid)
         for key, flag in flags_map.items():
             if client_only and not flag.get('clientSide', False):
                 continue

ldclient/client.py

@@ -598,7 +598,7 @@ def all_flags_state(self, context: Context, **kwargs) -> FeatureFlagsState:
             log.warning("Context was invalid for all_flags_state (%s); returning default value" % context.error)
             return FeatureFlagsState(False)
 
-        state = FeatureFlagsState(True)
+        valid = True
         client_only = kwargs.get('client_side_only', False)
         with_reasons = kwargs.get('with_reasons', False)
         details_only_if_tracked = kwargs.get('details_only_for_tracked_flags', False)
@@ -616,8 +616,18 @@ def all_flags_state(self, context: Context, **kwargs) -> FeatureFlagsState:
                     raise ValueError("feature store error")
             except Exception as e:
                 log.error("Unable to read flags for all_flag_state: %s" % repr(e))
-                return FeatureFlagsState(False)
+                # Overrides only add to the state. Without them the state is invalid and empty
+                # here, so it holds the override layer's flags and stays invalid. A client-side
+                # SDK bootstrapped from the state uses its flags whatever $valid says (the
+                # JavaScript client SDKs 3.x and 4.x only warn), so the overridden values still
+                # reach it.
+                layer = self._data_system.override_layer
+                flags_map = layer.all(FEATURES) if layer is not None else {}
+                if len(flags_map) == 0:
+                    return FeatureFlagsState(False)
+                valid = False
 
+        state = FeatureFlagsState(valid)
         for key, flag in flags_map.items():
             if client_only and not flag.get('clientSide', False):
                 continue

ldclient/testing/test_async_client_overrides.py

@@ -252,14 +252,32 @@ async def test_all_flags_state_before_initialization_excludes_launchdarkly_data_
 
 
 @pytest.mark.asyncio
-async def test_all_flags_state_is_invalid_when_the_store_fails_even_with_overrides(caplog):
-    # A daemon-mode client whose store cannot list its flags reports an invalid state and logs
-    # the failure, as it does without a source, rather than a valid state of the overrides alone.
+async def test_all_flags_state_holds_the_overrides_and_is_invalid_when_the_store_fails(caplog):
+    # A daemon-mode client whose store cannot list its flags logs the failure, as it does without
+    # a source. Overrides only add to the state, so it holds the override flags, and it stays
+    # invalid because the store's flags are missing.
     source = MockOverrideSource(flags={'overridden-flag': single_value_flag('overridden-flag', True)})
     datasystem = AsyncDataSystemConfig(override_source=source.builder, data_store=AsyncStoreThatCannotListItems(), data_store_mode=DataStoreMode.READ_ONLY)
     config = AsyncConfig('SDK_KEY', datasystem_config=datasystem, event_processor_class=lambda config: MockAsyncEventProcessor())
     client = AsyncLDClient(config)
     await client.start(start_wait=0)
+    try:
+        state = await client.all_flags_state(user, with_reasons=True)
+        assert state.valid is False
+        assert state.to_values_map() == {'overridden-flag': True}
+        assert state.get_flag_reason('overridden-flag') == {'kind': 'FALLTHROUGH', 'overrideAffected': True}
+        assert records_containing(caplog, logging.ERROR, 'Unable to read flags for all_flag_state') != []
+    finally:
+        await client.close()
+
+
+@pytest.mark.asyncio
+async def test_all_flags_state_is_invalid_and_empty_when_the_store_fails_and_the_layer_holds_no_flags(caplog):
+    source = MockOverrideSource()
+    datasystem = AsyncDataSystemConfig(override_source=source.builder, data_store=AsyncStoreThatCannotListItems(), data_store_mode=DataStoreMode.READ_ONLY)
+    config = AsyncConfig('SDK_KEY', datasystem_config=datasystem, event_processor_class=lambda config: MockAsyncEventProcessor())
+    client = AsyncLDClient(config)
+    await client.start(start_wait=0)
     try:
         state = await client.all_flags_state(user)
         assert state.valid is False

ldclient/testing/test_ldclient_overrides.py

@@ -208,12 +208,25 @@ def test_all_flags_state_before_initialization_excludes_launchdarkly_data_from_a
         assert state.to_values_map() == {'overridden-flag': True}
 
 
-def test_all_flags_state_is_invalid_when_the_store_fails_even_with_overrides(caplog):
-    # A daemon-mode client whose store cannot list its flags reports an invalid state and logs
-    # the failure, as it does without a source, rather than a valid state of the overrides alone.
+def test_all_flags_state_holds_the_overrides_and_is_invalid_when_the_store_fails(caplog):
+    # A daemon-mode client whose store cannot list its flags logs the failure, as it does without
+    # a source. Overrides only add to the state, so it holds the override flags, and it stays
+    # invalid because the store's flags are missing.
     source = MockOverrideSource(flags={'overridden-flag': single_value_flag('overridden-flag', True)})
     datasystem = daemon(StoreThatCannotListItems()).overrides(source.builder).build()
     config = Config(sdk_key='SDK_KEY', datasystem_config=datasystem, event_processor_class=MockEventProcessor)
+    with LDClient(config, start_wait=0) as client:
+        state = client.all_flags_state(user, with_reasons=True)
+        assert state.valid is False
+        assert state.to_values_map() == {'overridden-flag': True}
+        assert state.get_flag_reason('overridden-flag') == {'kind': 'FALLTHROUGH', 'overrideAffected': True}
+        assert errors_containing(caplog, 'Unable to read flags for all_flag_state') != []
+
+
+def test_all_flags_state_is_invalid_and_empty_when_the_store_fails_and_the_layer_holds_no_flags(caplog):
+    source = MockOverrideSource()
+    datasystem = daemon(StoreThatCannotListItems()).overrides(source.builder).build()
+    config = Config(sdk_key='SDK_KEY', datasystem_config=datasystem, event_processor_class=MockEventProcessor)
     with LDClient(config, start_wait=0) as client:
         state = client.all_flags_state(user)
         assert state.valid is False