Send x-llamastack-provider-data header with MCP auth to llama-stack

Author: max-svistunov

src/utils/responses.py

@@ -198,6 +198,37 @@ async def prepare_tools(
     return toolgroups
 
 
+def _build_provider_data_headers(
+    tools: Optional[list[dict[str, Any]]],
+) -> Optional[dict[str, str]]:
+    """Build extra HTTP headers containing MCP provider data for Llama Stack.
+
+    Extracts per-server auth headers from MCP tool definitions and encodes
+    them as a JSON ``x-llamastack-provider-data`` header that Llama Stack
+    uses to authenticate with downstream MCP servers.
+
+    Args:
+        tools: Prepared tool definitions (may include MCP and non-MCP tools).
+
+    Returns:
+        Dict with a single ``x-llamastack-provider-data`` key, or None when
+        no MCP tools carry headers.
+    """
+    if not tools:
+        return None
+
+    mcp_headers: McpHeaders = {
+        tool["server_url"]: tool["headers"]
+        for tool in tools
+        if tool.get("type") == "mcp" and tool.get("headers") and tool.get("server_url")
+    }
+
+    if not mcp_headers:
+        return None
+
+    return {"x-llamastack-provider-data": json.dumps({"mcp_headers": mcp_headers})}
+
+
 async def prepare_responses_params(  # pylint: disable=too-many-arguments,too-many-locals,too-many-positional-arguments
     client: AsyncLlamaStackClient,
     query_request: QueryRequest,
@@ -281,6 +312,9 @@ async def prepare_responses_params(  # pylint: disable=too-many-arguments,too-ma
             llama_stack_conv_id,
         )
 
+    # Build x-llamastack-provider-data header from MCP tool headers
+    extra_headers = _build_provider_data_headers(tools)
+
     return ResponsesApiParams(
         input=input_text,
         model=llama_stack_model_id,
@@ -289,6 +323,7 @@ async def prepare_responses_params(  # pylint: disable=too-many-arguments,too-ma
         conversation=llama_stack_conv_id,
         stream=stream,
         store=store,
+        extra_headers=extra_headers,
     )
 
 

src/utils/types.py

@@ -123,6 +123,10 @@ class ResponsesApiParams(BaseModel):
     conversation: str = Field(description="The conversation ID in llama-stack format")
     stream: bool = Field(description="Whether to stream the response")
     store: bool = Field(description="Whether to store the response")
+    extra_headers: Optional[dict[str, str]] = Field(
+        default=None,
+        description="Extra HTTP headers to send with the request (e.g. x-llamastack-provider-data)",
+    )
 
 
 class ToolCallSummary(BaseModel):

tests/unit/utils/test_responses.py

@@ -874,6 +874,111 @@ async def test_prepare_responses_params_api_status_error_on_models(
             await prepare_responses_params(mock_client, query_request, None, "token")
         assert exc_info.value.status_code == 500
 
+    @pytest.mark.asyncio
+    async def test_prepare_responses_params_includes_mcp_provider_data_headers(
+        self, mocker: MockerFixture
+    ) -> None:
+        """Test that extra_headers with x-llamastack-provider-data is set when MCP tools have headers."""
+        mock_client = mocker.AsyncMock()
+        mock_model = mocker.Mock()
+        mock_model.id = "provider1/model1"
+        mock_model.custom_metadata = {"model_type": "llm", "provider_id": "provider1"}
+        mock_client.models.list = mocker.AsyncMock(return_value=[mock_model])
+
+        mock_conversation = mocker.Mock()
+        mock_conversation.id = "new_conv_id"
+        mock_client.conversations.create = mocker.AsyncMock(
+            return_value=mock_conversation
+        )
+
+        query_request = QueryRequest(query="test")  # pyright: ignore[reportCallIssue]
+
+        # Simulate MCP tools with headers (as returned by prepare_tools/get_mcp_tools)
+        mcp_tools_with_headers = [
+            {
+                "type": "mcp",
+                "server_label": "mcp::aap-controller",
+                "server_url": "http://aap.foo.redhat.com:8004/sse",
+                "require_approval": "never",
+                "headers": {"X-Authorization": "client-token"},
+            },
+            {
+                "type": "mcp",
+                "server_label": "mcp::aap-lightspeed",
+                "server_url": "http://aap.foo.redhat.com:8005/sse",
+                "require_approval": "never",
+                "headers": {"X-Authorization": "client-token-2"},
+            },
+        ]
+
+        mocker.patch("utils.responses.configuration", mocker.Mock())
+        mocker.patch(
+            "utils.responses.select_model_and_provider_id",
+            return_value=("provider1/model1", "model1", "provider1"),
+        )
+        mocker.patch("utils.responses.evaluate_model_hints", return_value=(None, None))
+        mocker.patch("utils.responses.get_system_prompt", return_value="System prompt")
+        mocker.patch(
+            "utils.responses.prepare_tools", return_value=mcp_tools_with_headers
+        )
+        mocker.patch("utils.responses.prepare_input", return_value="test")
+
+        result = await prepare_responses_params(
+            mock_client, query_request, None, "token"
+        )
+
+        # The result should contain extra_headers with x-llamastack-provider-data
+        dumped = result.model_dump()
+        assert (
+            dumped["extra_headers"] is not None
+        ), "extra_headers should not be None when MCP tools have headers"
+        assert "x-llamastack-provider-data" in dumped["extra_headers"]
+
+        provider_data = json.loads(
+            dumped["extra_headers"]["x-llamastack-provider-data"]
+        )
+        assert "mcp_headers" in provider_data
+        assert provider_data["mcp_headers"] == {
+            "http://aap.foo.redhat.com:8004/sse": {"X-Authorization": "client-token"},
+            "http://aap.foo.redhat.com:8005/sse": {"X-Authorization": "client-token-2"},
+        }
+
+    @pytest.mark.asyncio
+    async def test_prepare_responses_params_no_extra_headers_without_mcp_tools(
+        self, mocker: MockerFixture
+    ) -> None:
+        """Test that extra_headers is None when no MCP tools have headers."""
+        mock_client = mocker.AsyncMock()
+        mock_model = mocker.Mock()
+        mock_model.id = "provider1/model1"
+        mock_model.custom_metadata = {"model_type": "llm", "provider_id": "provider1"}
+        mock_client.models.list = mocker.AsyncMock(return_value=[mock_model])
+
+        mock_conversation = mocker.Mock()
+        mock_conversation.id = "new_conv_id"
+        mock_client.conversations.create = mocker.AsyncMock(
+            return_value=mock_conversation
+        )
+
+        query_request = QueryRequest(query="test")  # pyright: ignore[reportCallIssue]
+
+        mocker.patch("utils.responses.configuration", mocker.Mock())
+        mocker.patch(
+            "utils.responses.select_model_and_provider_id",
+            return_value=("provider1/model1", "model1", "provider1"),
+        )
+        mocker.patch("utils.responses.evaluate_model_hints", return_value=(None, None))
+        mocker.patch("utils.responses.get_system_prompt", return_value="System prompt")
+        mocker.patch("utils.responses.prepare_tools", return_value=None)
+        mocker.patch("utils.responses.prepare_input", return_value="test")
+
+        result = await prepare_responses_params(
+            mock_client, query_request, None, "token"
+        )
+
+        dumped = result.model_dump()
+        assert dumped.get("extra_headers") is None
+
     @pytest.mark.asyncio
     async def test_prepare_responses_params_api_status_error_on_conversation(
         self, mocker: MockerFixture