[Fix] Claude Code (/messages) - Litellm fix claude code Bedrock Invoke usage, request signing (#19111)

* test_should_not_fail_with_forwarded_headers_bedrock_invoke_messages

* use common get_request_headers for BaseAWS

* fix get_request_headers

* test_should_not_fail_with_forwarded_headers_bedrock_invoke_messages

litellm/llms/bedrock/base_aws_llm.py

@@ -87,7 +87,7 @@ class BaseAWSLLM:
         """
         import litellm
         from litellm.secret_managers.main import str_to_bool
-        
+
         # Check environment variable first (highest priority)
         ssl_verify = os.getenv("SSL_VERIFY", litellm.ssl_verify)
         
@@ -1232,15 +1232,20 @@ class BaseAWSLLM:
         else:
             headers = {"Content-Type": "application/json"}
 
+        aws_signature_headers = self._filter_headers_for_aws_signature(headers)
         request = AWSRequest(
             method="POST",
             url=api_base,
             data=json.dumps(request_data),
-            headers=headers,
+            headers=aws_signature_headers,
         )
         sigv4.add_auth(request)
 
         request_headers_dict = dict(request.headers)
+        # Add back original headers after signing. Only headers in SignedHeaders
+        # are integrity-protected; forwarded headers (x-forwarded-*) must remain unsigned.
+        for header_name, header_value in headers.items():
+            request_headers_dict[header_name] = header_value
         if (
             headers is not None and "Authorization" in headers
         ):  # prevent sigv4 from overwriting the auth header

litellm/llms/bedrock/chat/invoke_handler.py

@@ -729,8 +729,6 @@ class BedrockLLM(BaseAWSLLM):
         client: Optional[Union[AsyncHTTPHandler, HTTPHandler]] = None,
     ) -> Union[ModelResponse, CustomStreamWrapper]:
         try:
-            from botocore.auth import SigV4Auth
-            from botocore.awsrequest import AWSRequest
             from botocore.credentials import Credentials
         except ImportError:
             raise ImportError("Missing boto3 to call bedrock. Run 'pip install boto3'.")
@@ -808,8 +806,6 @@ class BedrockLLM(BaseAWSLLM):
             endpoint_url = f"{endpoint_url}/model/{modelId}/invoke"
             proxy_endpoint_url = f"{proxy_endpoint_url}/model/{modelId}/invoke"
 
-        sigv4 = SigV4Auth(credentials, "bedrock", aws_region_name)
-
         prompt, chat_history = self.convert_messages_to_prompt(
             model, messages, provider, custom_prompt_dict
         )
@@ -970,15 +966,14 @@ class BedrockLLM(BaseAWSLLM):
         headers = {"Content-Type": "application/json"}
         if extra_headers is not None:
             headers = {"Content-Type": "application/json", **extra_headers}
-        request = AWSRequest(
-            method="POST", url=endpoint_url, data=data, headers=headers
+        prepped = self.get_request_headers(
+            credentials=credentials,
+            aws_region_name=aws_region_name,
+            extra_headers=extra_headers,
+            endpoint_url=endpoint_url,
+            data=data,
+            headers=headers,
         )
-        sigv4.add_auth(request)
-        if (
-            extra_headers is not None and "Authorization" in extra_headers
-        ):  # prevent sigv4 from overwriting the auth header
-            request.headers["Authorization"] = extra_headers["Authorization"]
-        prepped = request.prepare()
 
         ## LOGGING
         logging_obj.pre_call(

tests/pass_through_unit_tests/test_bedrock_anthropic_messages_test.py

@@ -6,7 +6,7 @@ from datetime import datetime
 from typing import AsyncIterator, Dict, Any
 import asyncio
 import unittest.mock
-from unittest.mock import AsyncMock, MagicMock
+from unittest.mock import MagicMock
 import pytest
 from litellm.router import Router
 
@@ -98,3 +98,44 @@ async def test_anthropic_messages_bedrock_converse_with_thinking():
 
     # Verify response
     INSTANCE_BASE_ANTHROPIC_MESSAGES_TEST._validate_response(response)
+
+
+@pytest.mark.asyncio
+async def test_should_not_fail_with_forwarded_headers_bedrock_invoke_messages():
+    """
+    E2E test for Bedrock invoke messages with header forwarding enabled.
+    This calls the real Bedrock endpoint (no mocks) and should not raise
+    SigV4 signature mismatch errors when forwarded headers are present.
+    """
+    router = Router(
+        model_list=[
+            {
+                "model_name": "claude-sonnet-4-5-20250929",
+                "litellm_params": {
+                    "model": "bedrock/invoke/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+                    "aws_region_name": os.getenv("AWS_REGION_NAME"),
+                },
+            }
+        ]
+    )
+
+    forwarded_headers = {
+        "x-forwarded-for": "10.11.232.194",
+        "x-forwarded-port": "443",
+        "x-forwarded-proto": "https",
+        "x-app": "cli",
+    }
+
+    response = await router.aanthropic_messages(
+        messages=[{"role": "user", "content": "hi"}],
+        model="claude-sonnet-4-5-20250929",
+        max_tokens=5,
+        stream=False,
+        headers=forwarded_headers,  # simulates forward_client_headers_to_llm_api
+        aws_access_key_id=os.getenv("AWS_ACCESS_KEY_ID"),
+        aws_secret_access_key=os.getenv("AWS_SECRET_ACCESS_KEY"),
+        aws_region_name=os.getenv("AWS_REGION_NAME"),
+    )
+    print("INVOKE API RESPONSE: ", response)
+
+    INSTANCE_BASE_ANTHROPIC_MESSAGES_TEST._validate_response(response)