splitio · chillaq · Sep 2, 2025 · Aug 25, 2025 · Aug 26, 2025 · Aug 26, 2025
diff --git a/splitio/client/config.py b/splitio/client/config.py
@@ -4,7 +4,8 @@
 from enum import Enum
 
 from splitio.engine.impressions import ImpressionsMode
-from splitio.client.input_validator import validate_flag_sets
+from splitio.client.input_validator import validate_flag_sets, validate_fallback_treatment, validate_regex_name
+from splitio.models.fallback_config import FallbackTreatmentsConfiguration
 
 _LOGGER = logging.getLogger(__name__)
 DEFAULT_DATA_SAMPLING = 1
@@ -69,7 +70,8 @@ class AuthenticateScheme(Enum):
     'flagSetsFilter': None,
     'httpAuthenticateScheme': AuthenticateScheme.NONE,
     'kerberosPrincipalUser': None,
-    'kerberosPrincipalPassword': None
+    'kerberosPrincipalPassword': None,
+    'fallbackTreatments': FallbackTreatmentsConfiguration(None)
 }
 
 def _parse_operation_mode(sdk_key, config):
@@ -168,4 +170,31 @@ def sanitize(sdk_key, config):
                             ' Defaulting to `none` mode.')
         processed["httpAuthenticateScheme"] = authenticate_scheme
 
+    processed = _sanitize_fallback_config(config, processed)    
+
     return processed
+
+def _sanitize_fallback_config(config, processed):
+    if config.get('fallbackTreatments') is not None:
+        if not isinstance(config['fallbackTreatments'], FallbackTreatmentsConfiguration):
+            _LOGGER.warning('Config: fallbackTreatments parameter should be of `FallbackTreatmentsConfiguration` class.')
+            processed['fallbackTreatments'] = None
+            return processed        
+
+        sanitized_global_fallback_treatment = config['fallbackTreatments'].global_fallback_treatment
+        if config['fallbackTreatments'].global_fallback_treatment is not None and not validate_fallback_treatment(config['fallbackTreatments'].global_fallback_treatment):
+            _LOGGER.warning('Config: global fallbacktreatment parameter is discarded.')
+            sanitized_global_fallback_treatment = None
+
+        sanitized_flag_fallback_treatments = {}
+        if config['fallbackTreatments'].by_flag_fallback_treatment is not None:
+            for feature_name in config['fallbackTreatments'].by_flag_fallback_treatment.keys():
+                if not validate_regex_name(feature_name) or not validate_fallback_treatment(config['fallbackTreatments'].by_flag_fallback_treatment[feature_name]):
+                    _LOGGER.warning('Config: fallback treatment parameter for feature flag %s is discarded.', feature_name)
+                    continue
+
+                sanitized_flag_fallback_treatments[feature_name] = config['fallbackTreatments'].by_flag_fallback_treatment[feature_name]
+
+        processed['fallbackTreatments'] = FallbackTreatmentsConfiguration(sanitized_global_fallback_treatment, sanitized_flag_fallback_treatments)
+
+    return processed
diff --git a/splitio/client/input_validator.py b/splitio/client/input_validator.py
@@ -8,14 +8,16 @@
 from splitio.client.key import Key
 from splitio.client import client
 from splitio.engine.evaluator import CONTROL
+from splitio.models.fallback_treatment import FallbackTreatment
 
 
 _LOGGER = logging.getLogger(__name__)
 MAX_LENGTH = 250
 EVENT_TYPE_PATTERN = r'^[a-zA-Z0-9][-_.:a-zA-Z0-9]{0,79}$'
 MAX_PROPERTIES_LENGTH_BYTES = 32768
 _FLAG_SETS_REGEX = '^[a-z0-9][_a-z0-9]{0,49}$'
-
+_FALLBACK_TREATMENT_REGEX = '^[a-zA-Z][a-zA-Z0-9-_;]+$'
+_FALLBACK_TREATMENT_SIZE = 100
 
 def _check_not_null(value, name, operation):
     """
@@ -712,3 +714,24 @@ def validate_flag_sets(flag_sets, method_name):
         sanitized_flag_sets.add(flag_set)
 
     return list(sanitized_flag_sets)
+
+def validate_fallback_treatment(fallback_treatment):
+    if not isinstance(fallback_treatment, FallbackTreatment):
+        _LOGGER.warning("Config: Fallback treatment instance should be FallbackTreatment, input is discarded")
+        return False
+
+    if not validate_regex_name(fallback_treatment.treatment):
+        _LOGGER.warning("Config: Fallback treatment should match regex %s", _FALLBACK_TREATMENT_REGEX)
+        return False
+
+    if len(fallback_treatment.treatment) > _FALLBACK_TREATMENT_SIZE:
+        _LOGGER.warning("Config: Fallback treatment size should not exceed %s characters", _FALLBACK_TREATMENT_SIZE)
+        return False
+
+    return True
+
+def validate_regex_name(name):
+    if re.match(_FALLBACK_TREATMENT_REGEX, name) == None:
+        return False
+
+    return True
diff --git a/splitio/models/fallback_config.py b/splitio/models/fallback_config.py
@@ -0,0 +1,37 @@
+"""Segment module."""
+
+class FallbackTreatmentsConfiguration(object):
+    """FallbackTreatmentsConfiguration object class."""
+
+    def __init__(self, global_fallback_treatment=None, by_flag_fallback_treatment=None):
+        """
+        Class constructor.
+
+        :param global_fallback_treatment: global FallbackTreatment.
+        :type global_fallback_treatment: FallbackTreatment
+
+        :param by_flag_fallback_treatment: Dict of flags and their fallback treatment
+        :type by_flag_fallback_treatment: {str: FallbackTreatment}
+        """
+        self._global_fallback_treatment = global_fallback_treatment
+        self._by_flag_fallback_treatment = by_flag_fallback_treatment
+
+    @property
+    def global_fallback_treatment(self):
+        """Return global fallback treatment."""
+        return self._global_fallback_treatment
+
+    @global_fallback_treatment.setter
+    def global_fallback_treatment(self, new_value):
+        """Set global fallback treatment."""
+        self._global_fallback_treatment = new_value
+
+    @property
+    def by_flag_fallback_treatment(self):
+        """Return by flag fallback treatment."""
+        return self._by_flag_fallback_treatment
+
+    @by_flag_fallback_treatment.setter
+    def by_flag_fallback_treatment(self, new_value):
+        """Set global fallback treatment."""
+        self.by_flag_fallback_treatment = new_value
diff --git a/splitio/models/fallback_treatment.py b/splitio/models/fallback_treatment.py
@@ -0,0 +1,36 @@
+"""Segment module."""
+import json
+
+class FallbackTreatment(object):
+    """FallbackTreatment object class."""
+
+    def __init__(self, treatment, config=None):
+        """
+        Class constructor.
+
+        :param treatment: treatment.
+        :type treatment: str
+
+        :param config: config.
+        :type config: json
+        """
+        self._treatment = treatment
+        self._config = None
+        if config != None:
+            self._config = json.dumps(config)
+        self._label_prefix = "fallback - "
+
+    @property
+    def treatment(self):
+        """Return treatment."""
+        return self._treatment
+
+    @property
+    def config(self):
+        """Return config."""
+        return self._config
+
+    @property
+    def label_prefix(self):
+        """Return label prefix."""
+        return self._label_prefix
diff --git a/tests/client/test_config.py b/tests/client/test_config.py
@@ -3,7 +3,8 @@
 import pytest
 from splitio.client import config
 from splitio.engine.impressions.impressions import ImpressionsMode
-
+from splitio.models.fallback_treatment import FallbackTreatment
+from splitio.models.fallback_config import FallbackTreatmentsConfiguration
 
 class ConfigSanitizationTests(object):
     """Inmemory storage-based integration tests."""
@@ -62,8 +63,10 @@ def test_sanitize_imp_mode(self):
         assert mode == ImpressionsMode.DEBUG
         assert rate == 60
 
-    def test_sanitize(self):
+    def test_sanitize(self, mocker):
         """Test sanitization."""
+        _logger = mocker.Mock()
+        mocker.patch('splitio.client.config._LOGGER', new=_logger)
         configs = {}
         processed = config.sanitize('some', configs)
         assert processed['redisLocalCacheEnabled']  # check default is True
@@ -87,3 +90,36 @@ def test_sanitize(self):
 
         processed = config.sanitize('some', {'httpAuthenticateScheme': 'NONE'})
         assert processed['httpAuthenticateScheme'] is config.AuthenticateScheme.NONE
+
+        _logger.reset_mock()
+        processed = config.sanitize('some', {'fallbackTreatments': 'NONE'})
+        assert processed['fallbackTreatments'] == None
+        assert _logger.warning.mock_calls[1] == mocker.call("Config: fallbackTreatments parameter should be of `FallbackTreatmentsConfiguration` class.")
+
+        _logger.reset_mock()
+        processed = config.sanitize('some', {'fallbackTreatments': FallbackTreatmentsConfiguration(123)})
+        assert processed['fallbackTreatments'].global_fallback_treatment == None
+        assert _logger.warning.mock_calls[1] == mocker.call("Config: global fallbacktreatment parameter is discarded.")
+
+        _logger.reset_mock()
+        processed = config.sanitize('some', {'fallbackTreatments': FallbackTreatmentsConfiguration(FallbackTreatment("123"))})
+        assert processed['fallbackTreatments'].global_fallback_treatment == None
+        assert _logger.warning.mock_calls[1] == mocker.call("Config: global fallbacktreatment parameter is discarded.")
+
+        fb = FallbackTreatmentsConfiguration(FallbackTreatment('on'))
+        processed = config.sanitize('some', {'fallbackTreatments': fb})
+        assert processed['fallbackTreatments'].global_fallback_treatment.treatment == fb.global_fallback_treatment.treatment
+        assert processed['fallbackTreatments'].global_fallback_treatment.label_prefix == "fallback - "
+
+        fb = FallbackTreatmentsConfiguration(FallbackTreatment('on'), {"flag": FallbackTreatment("off")})
+        processed = config.sanitize('some', {'fallbackTreatments': fb})
+        assert processed['fallbackTreatments'].global_fallback_treatment.treatment == fb.global_fallback_treatment.treatment
+        assert processed['fallbackTreatments'].by_flag_fallback_treatment["flag"] == fb.by_flag_fallback_treatment["flag"]
+        assert processed['fallbackTreatments'].by_flag_fallback_treatment["flag"].label_prefix == "fallback - "
+
+        _logger.reset_mock()
+        fb = FallbackTreatmentsConfiguration(None, {"flag#%": FallbackTreatment("off"), "flag2": FallbackTreatment("on")})
+        processed = config.sanitize('some', {'fallbackTreatments': fb})
+        assert len(processed['fallbackTreatments'].by_flag_fallback_treatment) == 1
+        assert processed['fallbackTreatments'].by_flag_fallback_treatment.get("flag2") == fb.by_flag_fallback_treatment["flag2"]
+        assert _logger.warning.mock_calls[1] == mocker.call('Config: fallback treatment parameter for feature flag %s is discarded.', 'flag#%')
diff --git a/tests/client/test_input_validator.py b/tests/client/test_input_validator.py
@@ -1,10 +1,8 @@
 """Unit tests for the input_validator module."""
-import logging
 import pytest
 
 from splitio.client.factory import SplitFactory, get_factory, SplitFactoryAsync, get_factory_async
 from splitio.client.client import CONTROL, Client, _LOGGER as _logger, ClientAsync
-from splitio.client.manager import SplitManager, SplitManagerAsync
 from splitio.client.key import Key
 from splitio.storage import SplitStorage, EventStorage, ImpressionStorage, SegmentStorage, RuleBasedSegmentsStorage
 from splitio.storage.inmemmory import InMemoryTelemetryStorage, InMemoryTelemetryStorageAsync, \
@@ -14,7 +12,7 @@
 from splitio.recorder.recorder import StandardRecorder, StandardRecorderAsync
 from splitio.engine.telemetry import TelemetryStorageProducer, TelemetryStorageProducerAsync
 from splitio.engine.impressions.impressions import Manager as ImpressionManager
-from splitio.engine.evaluator import EvaluationDataFactory
+from splitio.models.fallback_treatment import FallbackTreatment
 
 class ClientInputValidationTests(object):
     """Input validation test cases."""
@@ -1627,7 +1625,42 @@ def test_flag_sets_validation(self):
         flag_sets = input_validator.validate_flag_sets([12, 33], 'method')
         assert flag_sets == []
 
+    def test_fallback_treatments(self, mocker):
+        _logger = mocker.Mock()
+        mocker.patch('splitio.client.input_validator._LOGGER', new=_logger)
 
+        assert input_validator.validate_fallback_treatment(FallbackTreatment("on", {"prop":"val"}))
+        assert input_validator.validate_fallback_treatment(FallbackTreatment("on"))
+
+        _logger.reset_mock()
+        assert not input_validator.validate_fallback_treatment(FallbackTreatment("on" * 100))
+        assert _logger.warning.mock_calls == [
+            mocker.call("Config: Fallback treatment size should not exceed %s characters", 100)
+        ]
+
+        assert input_validator.validate_fallback_treatment(FallbackTreatment("on", {"prop" * 500:"val" * 500}))
+
+        _logger.reset_mock()
+        assert not input_validator.validate_fallback_treatment(FallbackTreatment("on/c"))
+        assert _logger.warning.mock_calls == [
+            mocker.call("Config: Fallback treatment should match regex %s", "^[a-zA-Z][a-zA-Z0-9-_;]+$")
+        ]
+
+        _logger.reset_mock()
+        assert not input_validator.validate_fallback_treatment(FallbackTreatment("9on"))
+        assert _logger.warning.mock_calls == [
+            mocker.call("Config: Fallback treatment should match regex %s", "^[a-zA-Z][a-zA-Z0-9-_;]+$")
+        ]
+
+        _logger.reset_mock()
+        assert not input_validator.validate_fallback_treatment(FallbackTreatment("on$as"))
+        assert _logger.warning.mock_calls == [
+            mocker.call("Config: Fallback treatment should match regex %s", "^[a-zA-Z][a-zA-Z0-9-_;]+$")
+        ]
+
+        assert input_validator.validate_fallback_treatment(FallbackTreatment("on_c"))
+        assert input_validator.validate_fallback_treatment(FallbackTreatment("on_45-c"))
+
 class ClientInputValidationAsyncTests(object):
     """Input validation test cases."""
 

diff --git a/tests/models/test_fallback.py b/tests/models/test_fallback.py
@@ -0,0 +1,32 @@
+from splitio.models.fallback_treatment import FallbackTreatment
+from splitio.models.fallback_config import FallbackTreatmentsConfiguration
+
+class FallbackTreatmentModelTests(object):
+    """Fallback treatment model tests."""
+
+    def test_working(self):
+        fallback_treatment = FallbackTreatment("on", {"prop": "val"})
+        assert fallback_treatment.config == '{"prop": "val"}'
+        assert fallback_treatment.treatment == 'on'
+
+        fallback_treatment = FallbackTreatment("off")
+        assert fallback_treatment.config == None
+        assert fallback_treatment.treatment == 'off'
+
+class FallbackTreatmentsConfigModelTests(object):
+    """Fallback treatment model tests."""
+
+    def test_working(self):
+        global_fb = FallbackTreatment("on")
+        flag_fb = FallbackTreatment("off")
+        fallback_config = FallbackTreatmentsConfiguration(global_fb, {"flag1": flag_fb})
+        assert fallback_config.global_fallback_treatment == global_fb
+        assert fallback_config.by_flag_fallback_treatment == {"flag1": flag_fb}
+
+        fallback_config.global_fallback_treatment = None
+        assert fallback_config.global_fallback_treatment == None
+
+        fallback_config.by_flag_fallback_treatment["flag2"] = flag_fb
+        assert fallback_config.by_flag_fallback_treatment == {"flag1": flag_fb, "flag2": flag_fb}
+
+