Merge 71cd2c30d1 into dab2deb5ed

litellm/constants.py

@@ -52,6 +52,7 @@ DEFAULT_S3_MAX_CONCURRENT_UPLOADS: Final = int(os.getenv("DEFAULT_S3_MAX_CONCURR
 DEFAULT_S3_MAX_ADAPTIVE_CONCURRENCY: Final = get_env_int("DEFAULT_S3_MAX_ADAPTIVE_CONCURRENCY", 200)
 # https://docs.aws.amazon.com/AmazonS3/latest/userguide/object-keys.html
 MAX_S3_OBJECT_KEY_BYTES: Final = 1024
+MAX_S3_OBJECT_KEY_FILENAME_BYTES: Final = 255
 S3_BOUNDED_OBJECT_KEY_HEAD_BYTES: Final = 64
 S3_PREFIX_DIGEST_CHARS: Final = 16
 # s3 allows 2048 bytes of combined metadata headers, which Content-Disposition counts against

litellm/integrations/s3.py

@@ -14,6 +14,7 @@ from litellm._logging import print_verbose, verbose_logger
 from litellm.constants import (
     MAX_S3_OBJECT_DOWNLOAD_FILENAME_BYTES,
     MAX_S3_OBJECT_KEY_BYTES,
+    MAX_S3_OBJECT_KEY_FILENAME_BYTES,
     S3_BOUNDED_OBJECT_KEY_HEAD_BYTES,
     S3_LOG_PROMPTS_ONLY_ENV_VAR,
     S3_PREFIX_DIGEST_CHARS,
@@ -375,21 +376,28 @@ def get_s3_object_key(
     sanitized_s3_file_name: Final = s3_file_name.replace("/", "_").replace(":", "_")
     configured_prefix: Final = (s3_path.rstrip("/") + "/" if s3_path else "") + prefix
     date_segment: Final = start_time.strftime("%Y-%m-%d") + "/"
+    extension: Final = ".json"
+    file_name_budget: Final = MAX_S3_OBJECT_KEY_FILENAME_BYTES - len(extension.encode("utf-8"))
     # we need the s3 key to include the time, so we log cache hits too
-    s3_object_key: Final = configured_prefix + date_segment + sanitized_s3_file_name + ".json"
-    if len(s3_object_key.encode("utf-8")) <= MAX_S3_OBJECT_KEY_BYTES:
+    s3_object_key: Final = configured_prefix + date_segment + sanitized_s3_file_name + extension
+    if (
+        len(s3_object_key.encode("utf-8")) <= MAX_S3_OBJECT_KEY_BYTES
+        and len(sanitized_s3_file_name.encode("utf-8")) <= file_name_budget
+    ):
         return s3_object_key
 
     # shorten the response id first and only trim the configured prefix if that is what does not
     # fit, so prefix scoped IAM policies and lifecycle rules keep matching
-    budget: Final = MAX_S3_OBJECT_KEY_BYTES - len(date_segment.encode("utf-8")) - len(b".json")
+    budget: Final = MAX_S3_OBJECT_KEY_BYTES - len(date_segment.encode("utf-8")) - len(extension.encode("utf-8"))
     prefix_bytes: Final = len(configured_prefix.encode("utf-8"))
     if prefix_bytes + S3_MIN_BOUNDED_FILE_NAME_BYTES <= budget:
-        bounded_file_name: Final = _bounded_s3_file_name(s3_file_name, sanitized_s3_file_name, budget - prefix_bytes)
-        return configured_prefix + date_segment + bounded_file_name + ".json"
+        bounded_file_name: Final = _bounded_s3_file_name(
+            s3_file_name, sanitized_s3_file_name, min(file_name_budget, budget - prefix_bytes)
+        )
+        return configured_prefix + date_segment + bounded_file_name + extension
 
     shortest_file_name: Final = _bounded_s3_file_name(
         s3_file_name, sanitized_s3_file_name, S3_MIN_BOUNDED_FILE_NAME_BYTES
     )
     bounded_prefix: Final = _bounded_s3_prefix(configured_prefix, budget - len(shortest_file_name.encode("utf-8")))
-    return bounded_prefix + date_segment + shortest_file_name + ".json"
+    return bounded_prefix + date_segment + shortest_file_name + extension

tests/unit/integrations/test_s3_v2.py

@@ -1387,25 +1387,76 @@ def test_create_s3_batch_logging_element_flat_key_for_arn_response_id():
 
 
 # --------------------------------------------------------------
-# object keys bounded to S3's 1024 UTF-8 byte limit
+# object keys bounded to S3 and filesystem-compatible limits
 # --------------------------------------------------------------
 def _oversized_response_id() -> str:
     return "resp_" + "A" * 1100
 
 
-def test_s3_object_key_at_the_byte_limit_is_left_alone():
-    """A key that still fits is left byte-identical."""
-    from litellm.constants import MAX_S3_OBJECT_KEY_BYTES
+def test_s3_object_key_at_the_segment_byte_limit_is_left_alone():
+    """A final key segment that still fits is left byte-identical."""
     from litellm.integrations.s3 import get_s3_object_key
 
     start_time = datetime(2026, 8, 24, 6, 18, 41, 948021)
-    fixed_len = len("input/2026-08-24/.json")
-    file_name = "x" * (MAX_S3_OBJECT_KEY_BYTES - fixed_len)
+    file_name = "x" * 250
 
     key = get_s3_object_key(s3_path="input", prefix="", start_time=start_time, s3_file_name=file_name)
 
     assert key == f"input/2026-08-24/{file_name}.json"
-    assert len(key.encode("utf-8")) == MAX_S3_OBJECT_KEY_BYTES
+    assert len(key.rsplit("/", 1)[1].encode("utf-8")) == 255
+
+
+def test_s3_object_key_just_over_the_file_name_limit_is_bounded():
+    """A 256-byte final key segment is shortened below the local filesystem limit."""
+    from litellm.integrations.s3 import get_s3_object_key
+
+    key = get_s3_object_key(
+        s3_path="input",
+        prefix="",
+        start_time=datetime(2026, 8, 24, 6, 18, 41, 948021),
+        s3_file_name="x" * 251,
+    )
+
+    assert len(key.rsplit("/", 1)[1].encode("utf-8")) <= 255
+
+
+def test_s3_object_key_bounds_the_file_segment_when_the_full_key_fits():
+    """A locally stored object name is bounded even when its full S3 key is below 1024 bytes."""
+    import hashlib
+
+    from litellm.constants import MAX_S3_OBJECT_KEY_BYTES
+    from litellm.integrations.s3 import get_s3_object_key
+
+    file_name = "time-01-14-19-015434_resp_" + "A" * 300
+
+    key = get_s3_object_key(
+        s3_path="requests",
+        prefix="",
+        start_time=datetime(2026, 9, 12, 1, 14, 19, 15434),
+        s3_file_name=file_name,
+    )
+
+    file_segment = key.rsplit("/", 1)[1]
+    assert len(key.encode("utf-8")) < MAX_S3_OBJECT_KEY_BYTES
+    assert len(file_segment.encode("utf-8")) <= 255
+    assert file_segment.startswith("time-01-14-19-015434_resp_")
+    assert file_segment.endswith(f"_{hashlib.sha256(file_name.encode('utf-8')).hexdigest()}.json")
+
+
+def test_s3_object_key_file_segment_limit_counts_utf8_bytes():
+    """The final key segment is bounded by encoded bytes without splitting a character."""
+    from litellm.integrations.s3 import get_s3_object_key
+
+    key = get_s3_object_key(
+        s3_path="requests",
+        prefix="",
+        start_time=datetime(2026, 9, 12, 1, 14, 19, 15434),
+        s3_file_name="time-01-14-19-015434_resp_" + "日" * 100,
+    )
+
+    file_segment = key.rsplit("/", 1)[1]
+    assert len(file_segment.encode("utf-8")) <= 255
+    assert "\ufffd" not in file_segment
 
 
 def test_s3_object_key_is_bounded_for_oversized_response_id():