Port of boto/botocore#3568

SamRemis · SamRemis · commit f80be2284aef · 2025-12-09T13:22:23.000-05:00
diff --git a/awscli/botocore/args.py b/awscli/botocore/args.py
@@ -146,8 +146,23 @@ def get_client_args(
             proxies_config=new_config.proxies_config,
         )
 
+
+        # Emit event to allow service-specific or customer customization of serializer kwargs
+        event_name = f'creating-serializer.{service_name}'
+        serializer_kwargs = {
+            'timestamp_precision': botocore.serialize.TIMESTAMP_PRECISION_DEFAULT
+        }
+        event_emitter.emit(
+            event_name,
+            protocol_name=protocol,
+            service_model=service_model,
+            serializer_kwargs=serializer_kwargs,
+        )
+
         serializer = botocore.serialize.create_serializer(
-            protocol, parameter_validation
+            protocol,
+            parameter_validation,
+            timestamp_precision=serializer_kwargs['timestamp_precision'],
         )
         response_parser = botocore.parsers.create_parser(protocol)
 
diff --git a/awscli/botocore/handlers.py b/awscli/botocore/handlers.py
@@ -53,6 +53,7 @@
     UnsupportedTLSVersionWarning,
 )
 from botocore.regions import EndpointResolverBuiltins
+from botocore.serialize import TIMESTAMP_PRECISION_MILLISECOND
 from botocore.signers import (
     add_dsql_generate_db_auth_token_methods,
     add_generate_db_auth_token,
@@ -995,6 +996,10 @@ def remove_bedrock_runtime_invoke_model_with_bidirectional_stream(
     if 'invoke_model_with_bidirectional_stream' in class_attributes:
         del class_attributes['invoke_model_with_bidirectional_stream']
 
+def enable_millisecond_timestamp_precision(serializer_kwargs, **kwargs):
+    """Event handler to enable millisecond precision"""
+    serializer_kwargs['timestamp_precision'] = TIMESTAMP_PRECISION_MILLISECOND
+
 
 def remove_bucket_from_url_paths_from_model(params, model, context, **kwargs):
     """Strips leading `{Bucket}/` from any operations that have it.
@@ -1345,6 +1350,10 @@ def _set_extra_headers_for_unsigned_request(
         'creating-client-class.bedrock-runtime',
         remove_bedrock_runtime_invoke_model_with_bidirectional_stream,
     ),
+    (
+        'creating-serializer.bedrock-agentcore',
+        enable_millisecond_timestamp_precision,
+    ),
     ('after-call.iam', json_decode_policies),
     ('after-call.ec2.GetConsoleOutput', decode_console_output),
     ('after-call.cloudformation.GetTemplate', json_decode_template_body),
diff --git a/awscli/botocore/serialize.py b/awscli/botocore/serialize.py
@@ -63,10 +63,32 @@
 # Same as ISO8601, but with microsecond precision.
 ISO8601_MICRO = '%Y-%m-%dT%H:%M:%S.%fZ'
 
+TIMESTAMP_PRECISION_DEFAULT = 'default'
+TIMESTAMP_PRECISION_MILLISECOND = 'millisecond'
+TIMESTAMP_PRECISION_OPTIONS = (
+    TIMESTAMP_PRECISION_DEFAULT,
+    TIMESTAMP_PRECISION_MILLISECOND,
+)
 
-def create_serializer(protocol_name, include_validation=True):
-    # TODO: Unknown protocols.
-    serializer = SERIALIZERS[protocol_name]()
+def create_serializer(
+            protocol_name,
+            include_validation=True,
+            timestamp_precision=TIMESTAMP_PRECISION_DEFAULT,
+    ):
+    """Create a serializer for the given protocol.
+    :param protocol_name: The protocol name to create a serializer for.
+    :type protocol_name: str
+    :param include_validation: Whether to include parameter validation.
+    :type include_validation: bool
+    :param timestamp_precision: Timestamp precision level.
+        - 'default': Microseconds for ISO timestamps, seconds for Unix and RFC
+        - 'millisecond': Millisecond precision (ISO/Unix), seconds for RFC
+    :type timestamp_precision: str
+    :return: A serializer instance for the given protocol.
+    """
+    serializer = SERIALIZERS[protocol_name](
+        timestamp_precision=timestamp_precision
+    )
     if include_validation:
         validator = validate.ParamValidator()
         serializer = validate.ParamValidationDecorator(validator, serializer)
@@ -82,6 +104,14 @@ class Serializer:
     MAP_TYPE = dict
     DEFAULT_ENCODING = 'utf-8'
 
+    def __init__(self, timestamp_precision=TIMESTAMP_PRECISION_DEFAULT):
+        if timestamp_precision not in TIMESTAMP_PRECISION_OPTIONS:
+            raise ValueError(
+                f"Invalid timestamp precision found while creating serializer: {timestamp_precision}"
+            )
+
+        self._timestamp_precision = timestamp_precision
+
     def serialize_to_request(self, parameters, operation_model):
         """Serialize parameters into an HTTP request.
 
@@ -136,16 +166,33 @@ def _create_default_request(self):
     # Some extra utility methods subclasses can use.
 
     def _timestamp_iso8601(self, value):
-        if value.microsecond > 0:
-            timestamp_format = ISO8601_MICRO
+        """Return ISO8601 timestamp with precision based on timestamp_precision."""
+        # Smithy's standard is milliseconds, so we truncate the timestamp if the millisecond flag is set to true
+        if self._timestamp_precision == TIMESTAMP_PRECISION_MILLISECOND:
+            milliseconds = value.microsecond // 1000
+            return (
+                value.strftime('%Y-%m-%dT%H:%M:%S') + f'.{milliseconds:03d}Z'
+            )
         else:
-            timestamp_format = ISO8601
-        return value.strftime(timestamp_format)
+            # Otherwise we continue supporting microseconds in iso8601 for legacy reasons
+            if value.microsecond > 0:
+                timestamp_format = ISO8601_MICRO
+            else:
+                timestamp_format = ISO8601
+            return value.strftime(timestamp_format)
 
     def _timestamp_unixtimestamp(self, value):
-        return int(calendar.timegm(value.timetuple()))
+        """Return unix timestamp with precision based on timestamp_precision."""
+        # As of the addition of the precision flag, we support millisecond precision here as well
+        if self._timestamp_precision == TIMESTAMP_PRECISION_MILLISECOND:
+            base_timestamp = calendar.timegm(value.timetuple())
+            milliseconds = (value.microsecond // 1000) / 1000.0
+            return base_timestamp + milliseconds
+        else:
+            return int(calendar.timegm(value.timetuple()))
 
     def _timestamp_rfc822(self, value):
+        """Return RFC822 timestamp (always second precision - RFC doesn't support sub-second)."""
         if isinstance(value, datetime.datetime):
             value = self._timestamp_unixtimestamp(value)
         return formatdate(value, usegmt=True)
diff --git a/tests/unit/botocore/test_serialize.py b/tests/unit/botocore/test_serialize.py
@@ -23,6 +23,10 @@
 from botocore.exceptions import ParamValidationError
 from botocore.model import ServiceModel
 from botocore.serialize import SERIALIZERS
+from botocore.serialize import (
+    TIMESTAMP_PRECISION_DEFAULT,
+    TIMESTAMP_PRECISION_MILLISECOND,
+)
 
 from tests import unittest
 
@@ -614,3 +618,120 @@ def test_restxml_serializes_unicode(self):
             self.serialize_to_request(params)
         except UnicodeEncodeError:
             self.fail("RestXML serializer failed to serialize unicode text.")
+
+
+class TestTimestampPrecisionParameter(unittest.TestCase):
+    def setUp(self):
+        self.model = {
+            'metadata': {'protocol': 'query', 'apiVersion': '2014-01-01'},
+            'documentation': '',
+            'operations': {
+                'TestOperation': {
+                    'name': 'TestOperation',
+                    'http': {
+                        'method': 'POST',
+                        'requestUri': '/',
+                    },
+                    'input': {'shape': 'InputShape'},
+                }
+            },
+            'shapes': {
+                'InputShape': {
+                    'type': 'structure',
+                    'members': {
+                        'UnixTimestamp': {'shape': 'UnixTimestampType'},
+                        'IsoTimestamp': {'shape': 'IsoTimestampType'},
+                        'Rfc822Timestamp': {'shape': 'Rfc822TimestampType'},
+                    },
+                },
+                'IsoTimestampType': {
+                    'type': 'timestamp',
+                    "timestampFormat": "iso8601",
+                },
+                'UnixTimestampType': {
+                    'type': 'timestamp',
+                    "timestampFormat": "unixTimestamp",
+                },
+                'Rfc822TimestampType': {
+                    'type': 'timestamp',
+                    "timestampFormat": "rfc822",
+                },
+            },
+        }
+        self.service_model = ServiceModel(self.model)
+
+    def serialize_to_request(
+        self, input_params, timestamp_precision=TIMESTAMP_PRECISION_DEFAULT
+    ):
+        request_serializer = serialize.create_serializer(
+            self.service_model.metadata['protocol'],
+            timestamp_precision=timestamp_precision,
+        )
+        return request_serializer.serialize_to_request(
+            input_params, self.service_model.operation_model('TestOperation')
+        )
+
+    def test_second_precision_maintains_existing_behavior(self):
+        test_datetime = datetime.datetime(2024, 1, 1, 12, 0, 0, 123456)
+        request = self.serialize_to_request(
+            {'UnixTimestamp': test_datetime, 'IsoTimestamp': test_datetime}
+        )
+        # To maintain backwards compatibility, unix should not include milliseconds by default
+        self.assertEqual(1704110400, request['body']['UnixTimestamp'])
+
+        # ISO always supported microseconds, so we need to continue supporting this
+        self.assertEqual(
+            '2024-01-01T12:00:00.123456Z',
+            request['body']['IsoTimestamp'],
+        )
+
+    def test_millisecond_precision_serialization(self):
+        test_datetime = datetime.datetime(2024, 1, 1, 12, 0, 0, 123456)
+
+        # Check that millisecond precision is used when it is opted in to via the input param
+        request = self.serialize_to_request(
+            {'UnixTimestamp': test_datetime, 'IsoTimestamp': test_datetime},
+            TIMESTAMP_PRECISION_MILLISECOND,
+        )
+        self.assertEqual(1704110400.123, request['body']['UnixTimestamp'])
+        self.assertEqual(
+            '2024-01-01T12:00:00.123Z',
+            request['body']['IsoTimestamp'],
+        )
+
+    def test_millisecond_precision_with_zero_microseconds(self):
+        test_datetime = datetime.datetime(2024, 1, 1, 12, 0, 0, 0)
+
+        request = self.serialize_to_request(
+            {'UnixTimestamp': test_datetime, 'IsoTimestamp': test_datetime},
+            TIMESTAMP_PRECISION_MILLISECOND,
+        )
+        self.assertEqual(1704110400.0, request['body']['UnixTimestamp'])
+        self.assertEqual(
+            '2024-01-01T12:00:00.000Z',
+            request['body']['IsoTimestamp'],
+        )
+
+    def test_rfc822_timestamp_always_uses_second_precision(self):
+        # RFC822 format doesn't support sub-second precision.
+        test_datetime = datetime.datetime(2024, 1, 1, 12, 0, 0, 123456)
+        request_second = self.serialize_to_request(
+            {'Rfc822Timestamp': test_datetime},
+        )
+        request_milli = self.serialize_to_request(
+            {'Rfc822Timestamp': test_datetime}, TIMESTAMP_PRECISION_MILLISECOND
+        )
+        self.assertEqual(
+            request_second['body']['Rfc822Timestamp'],
+            request_milli['body']['Rfc822Timestamp'],
+        )
+        self.assertIn('2024', request_second['body']['Rfc822Timestamp'])
+        self.assertIn('GMT', request_second['body']['Rfc822Timestamp'])
+
+    def test_invalid_timestamp_precision_raises_error(self):
+        with self.assertRaises(ValueError) as context:
+            serialize.create_serializer(
+                self.service_model.metadata['protocol'],
+                timestamp_precision='invalid',
+            )
+        self.assertIn("Invalid timestamp precision", str(context.exception))
