[Fix]: /messages - allow using dynamic AWS params (#10769)

* fix: dynamic AWS params added for messages routes

* Update tests/pass_through_unit_tests/test_anthropic_messages_passthrough.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

litellm/llms/custom_httpx/llm_http_handler.py

@@ -1118,7 +1118,9 @@ class BaseLLMHTTPHandler:
 
         headers, signed_json_body = anthropic_messages_provider_config.sign_request(
             headers=headers,
-            optional_params=anthropic_messages_optional_request_params,
+            optional_params=dict(
+                litellm_params
+            ),  # dynamic aws_* params are passed under litellm_params
             request_data=request_body,
             api_base=request_url,
             stream=stream,

tests/pass_through_unit_tests/test_anthropic_messages_passthrough.py

@@ -23,6 +23,7 @@ from litellm.integrations.custom_logger import CustomLogger
 from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler
 from litellm.router import Router
 import importlib
+from litellm.llms.bedrock.base_aws_llm import BaseAWSLLM
 
 # Load environment variables
 load_dotenv()
@@ -612,3 +613,67 @@ async def test_anthropic_messages_with_thinking():
     assert response == mock_response.json.return_value
 
     return response
+
+
+@pytest.mark.asyncio
+async def test_anthropic_messages_bedrock_credentials_passthrough():
+    """
+    Test that AWS credentials are correctly passed through to BaseAWSLLM.get_credentials
+    when using anthropic.messages.acreate with a bedrock model
+    """
+    # Mock the get_credentials method
+    with unittest.mock.patch.object(BaseAWSLLM, 'get_credentials') as mock_get_credentials:
+        # Create a proper mock for credentials with the necessary attributes
+        mock_credentials = unittest.mock.MagicMock()
+        mock_credentials.access_key = "mock_access_key"
+        mock_credentials.secret_key = "mock_secret_key"
+        mock_credentials.token = "mock_session_token"
+        mock_get_credentials.return_value = mock_credentials
+        
+        # We also need to mock the actual AWS request signing to avoid real API calls
+        with unittest.mock.patch('botocore.auth.SigV4Auth.add_auth'):
+            # Set up mock for AsyncHTTPHandler.post to avoid actual API calls
+            with unittest.mock.patch('litellm.llms.custom_httpx.http_handler.AsyncHTTPHandler.post') as mock_post:
+                # Configure mock response
+                mock_response = unittest.mock.MagicMock()
+                mock_response.raise_for_status = unittest.mock.MagicMock()
+                mock_response.json.return_value = {
+                    "id": "msg_bedrock_123",
+                    "type": "message",
+                    "role": "assistant",
+                    "content": [{"type": "text", "text": "This is a mock response"}],
+                    "model": "bedrock/us.anthropic.claude-3-5-sonnet-20240620-v1:0",
+                    "stop_reason": "end_turn",
+                    "usage": {"input_tokens": 10, "output_tokens": 20},
+                }
+                mock_post.return_value = mock_response
+                
+                # Test all AWS credentials parameters
+                test_params = {
+                    "aws_access_key_id": "test_access_key",
+                    "aws_secret_access_key": "test_secret_key",
+                    "aws_session_token": "test_session_token",
+                    "aws_region_name": "us-west-2",
+                    "aws_role_name": "test_role_name",
+                    "aws_session_name": "test_session_name",
+                    "aws_profile_name": "test_profile",
+                    "aws_web_identity_token": "test_web_identity_token",
+                    "aws_sts_endpoint": "https://sts.test-region.amazonaws.com",
+                }
+                
+                # Call the function with AWS credentials
+                await litellm.anthropic.messages.acreate(
+                    messages=[{"role": "user", "content": "Hello, test credentials"}],
+                    model="bedrock/us.anthropic.claude-3-5-sonnet-20240620-v1:0",
+                    max_tokens=100,
+                    **test_params
+                )
+                
+                # Verify get_credentials was called with the correct parameters
+                mock_get_credentials.assert_called_once()
+                call_args = mock_get_credentials.call_args[1]
+                
+                # Assert that our test credentials were passed correctly
+                for param_name, param_value in test_params.items():
+                    assert call_args[param_name] == param_value, f"Parameter {param_name} was not passed correctly"
+