fix: prioritize boto3 environment region resolution and log actual client regions

Author: “Sundar”

src/bedrock_agentcore/memory/client.py

@@ -40,13 +40,16 @@ class MemoryClient:
 
     def __init__(self, region_name: Optional[str] = None):
         """Initialize the Memory client."""
-        self.gmcp_client = boto3.client("bedrock-agentcore-control", region_name=region_name)
-        self.gmdp_client = boto3.client("bedrock-agentcore", region_name=region_name)
+        self.region_name = boto3.Session().region_name or region_name or "us-west-2"
 
-        # Store the region that was actually used
-        self.region_name = region_name if region_name else boto3.Session().region_name or "us-west-2"
+        self.gmcp_client = boto3.client("bedrock-agentcore-control", region_name=self.region_name)
+        self.gmdp_client = boto3.client("bedrock-agentcore", region_name=self.region_name)
 
-        logger.info("Initialized MemoryClient for %s", self.region_name)
+        logger.info(
+            "Initialized MemoryClient for control plane: %s, data plane: %s",
+            self.gmcp_client.meta.region_name,
+            self.gmdp_client.meta.region_name,
+        )
 
     def create_memory(
         self,

tests/bedrock_agentcore/memory/test_client.py

@@ -30,8 +30,9 @@ def test_client_initialization_region_mismatch():
     """Test client initialization with region mismatch warning."""
 
     with patch("boto3.client") as mock_boto_client:
+        # First test - environment variable takes precedence
         with patch("boto3.Session") as mock_session:
-            # Mock the session instance
+            # Mock the session instance to simulate AWS_REGION=us-east-1
             mock_session_instance = MagicMock()
             mock_session_instance.region_name = "us-east-1"
             mock_session.return_value = mock_session_instance
@@ -41,17 +42,23 @@ def test_client_initialization_region_mismatch():
             mock_client_instance.meta.region_name = "us-east-1"
             mock_boto_client.return_value = mock_client_instance
 
-            # When region_name is not provided, it should use the boto3 default
-            client1 = MemoryClient()
-            assert client1.region_name == "us-east-1"
+            # When region_name is provided, environment variable should still take precedence
+            client1 = MemoryClient(region_name="us-west-2")
+            assert client1.region_name == "us-east-1"  # Environment wins over explicit param
 
-            # Reset the mock to test with a specified region
-            mock_boto_client.reset_mock()
+        # Second test - no environment variable, explicit param is used
+        with patch("boto3.Session") as mock_session:
+            # Mock the session instance to simulate no AWS_REGION set
+            mock_session_instance = MagicMock()
+            mock_session_instance.region_name = None
+            mock_session.return_value = mock_session_instance
+
+            # Mock the boto client
             mock_client_instance = MagicMock()
             mock_client_instance.meta.region_name = "us-west-2"
             mock_boto_client.return_value = mock_client_instance
 
-            # When region_name is provided, it should use that value
+            # When AWS_REGION is not set, explicitly provided region should be used
             client2 = MemoryClient(region_name="us-west-2")
             assert client2.region_name == "us-west-2"