fix: keep sagemaker_session from being overridden to None (#5021)

* fix: keep sagemaker_session from being overridden to None, add unit/integ tests

* remove commented code

* fix styling issues

---------

Co-authored-by: Zhaoqi <jzhaoqwa@amazon.com>

Author: Narrohag

src/sagemaker/jumpstart/cache.py

@@ -150,7 +150,8 @@ def __init__(
             if s3_client_config
             else boto3.client("s3", region_name=self._region)
         )
-        self._sagemaker_session = sagemaker_session
+        # Fallback in case a caller overrides sagemaker_session to None
+        self._sagemaker_session = sagemaker_session or DEFAULT_JUMPSTART_SAGEMAKER_SESSION
 
     def set_region(self, region: str) -> None:
         """Set region for cache. Clears cache after new region is set."""

src/sagemaker/jumpstart/hub/utils.py

@@ -78,6 +78,9 @@ def construct_hub_arn_from_name(
     account_id: Optional[str] = None,
 ) -> str:
     """Constructs a Hub arn from the Hub name using default Session values."""
+    if session is None:
+        # session is overridden to none by some callers
+        session = constants.DEFAULT_JUMPSTART_SAGEMAKER_SESSION
 
     account_id = account_id or session.account_id()
     region = region or session.boto_region_name
@@ -211,6 +214,9 @@ def get_hub_model_version(
         ClientError: If the specified model is not found in the hub.
         KeyError: If the specified model version is not found.
     """
+    if sagemaker_session is None:
+        # sagemaker_session is overridden to none by some callers
+        sagemaker_session = constants.DEFAULT_JUMPSTART_SAGEMAKER_SESSION
 
     try:
         hub_content_summaries = sagemaker_session.list_hub_content_versions(

tests/integ/sagemaker/jumpstart/private_hub/model/test_jumpstart_private_hub_model.py

@@ -82,6 +82,23 @@ def test_jumpstart_hub_model(setup, add_model_references):
     assert sagemaker_session.endpoint_in_service_or_not(predictor.endpoint_name)
 
 
+def test_jumpstart_hub_model_with_default_session(setup, add_model_references):
+    model_version = "*"
+    hub_name = os.environ[ENV_VAR_JUMPSTART_SDK_TEST_HUB_NAME]
+
+    model_id = "catboost-classification-model"
+
+    sagemaker_session = get_sm_session()
+
+    model = JumpStartModel(model_id=model_id, model_version=model_version, hub_name=hub_name)
+
+    predictor = model.deploy(
+        tags=[{"Key": JUMPSTART_TAG, "Value": os.environ[ENV_VAR_JUMPSTART_SDK_TEST_SUITE_ID]}],
+    )
+
+    assert sagemaker_session.endpoint_in_service_or_not(predictor.endpoint_name)
+
+
 def test_jumpstart_hub_gated_model(setup, add_model_references):
 
     model_id = "meta-textgeneration-llama-3-2-1b"

tests/unit/sagemaker/jumpstart/hub/test_utils.py

@@ -14,7 +14,10 @@
 
 from unittest.mock import patch, Mock
 from sagemaker.jumpstart.types import HubArnExtractedInfo
-from sagemaker.jumpstart.constants import JUMPSTART_DEFAULT_REGION_NAME
+from sagemaker.jumpstart.constants import (
+    JUMPSTART_DEFAULT_REGION_NAME,
+    DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
+)
 from sagemaker.jumpstart.hub import parser_utils, utils
 
 
@@ -80,6 +83,17 @@ def test_construct_hub_arn_from_name():
     )
 
 
+def test_construct_hub_arn_from_name_with_session_none():
+    hub_name = "my-cool-hub"
+    account_id = DEFAULT_JUMPSTART_SAGEMAKER_SESSION.account_id()
+    boto_region_name = DEFAULT_JUMPSTART_SAGEMAKER_SESSION.boto_region_name
+
+    assert (
+        utils.construct_hub_arn_from_name(hub_name=hub_name, session=None)
+        == f"arn:aws:sagemaker:{boto_region_name}:{account_id}:hub/{hub_name}"
+    )
+
+
 def test_construct_hub_model_arn_from_inputs():
     model_name, version = "pytorch-ic-imagenet-v2", "1.0.2"
     hub_arn = "arn:aws:sagemaker:us-west-2:123456789123:hub/my-mock-hub"

tests/unit/sagemaker/jumpstart/test_cache.py

@@ -29,6 +29,7 @@
 from sagemaker.jumpstart.cache import (
     JUMPSTART_DEFAULT_MANIFEST_FILE_S3_KEY,
     JUMPSTART_DEFAULT_PROPRIETARY_MANIFEST_KEY,
+    DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
     JumpStartModelsCache,
 )
 from sagemaker.jumpstart.constants import (
@@ -57,6 +58,25 @@
 from sagemaker.jumpstart.utils import get_jumpstart_content_bucket
 
 
+@patch("sagemaker.jumpstart.utils.get_region_fallback", lambda *args, **kwargs: "dummy-region")
+@patch(
+    "sagemaker.jumpstart.utils.get_jumpstart_content_bucket", lambda *args, **kwargs: "dummy-bucket"
+)
+@patch("boto3.client")
+def test_jumpstart_cache_init(mock_boto3_client):
+    cache = JumpStartModelsCache()
+    assert cache._region == "dummy-region"
+    assert cache.s3_bucket_name == "dummy-bucket"
+    assert cache._manifest_file_s3_key == JUMPSTART_DEFAULT_MANIFEST_FILE_S3_KEY
+    assert cache._proprietary_manifest_s3_key == JUMPSTART_DEFAULT_PROPRIETARY_MANIFEST_KEY
+    assert cache._sagemaker_session == DEFAULT_JUMPSTART_SAGEMAKER_SESSION
+    mock_boto3_client.assert_called_once_with("s3", region_name="dummy-region")
+
+    # Some callers override the session to None, should still be set to default
+    cache = JumpStartModelsCache(sagemaker_session=None)
+    assert cache._sagemaker_session == DEFAULT_JUMPSTART_SAGEMAKER_SESSION
+
+
 @patch.object(JumpStartModelsCache, "_retrieval_function", patched_retrieval_function)
 @patch("sagemaker.jumpstart.utils.get_sagemaker_version", lambda: "2.68.3")
 def test_jumpstart_cache_get_header():