From 72681052cdcbf21c1e04ba91383f51da33f103bd Mon Sep 17 00:00:00 2001
From: Timothy Jaeryang Baek <tim@openwebui.com>
Date: Sun, 30 Mar 2025 00:14:24 -0700
Subject: [PATCH] feat: mcp proxy

---
 servers/mcp-proxy/main.py | 160 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)

diff --git a/servers/mcp-proxy/main.py b/servers/mcp-proxy/main.py
index e69de29..4a27489 100644
--- a/servers/mcp-proxy/main.py
+++ b/servers/mcp-proxy/main.py
@@ -0,0 +1,160 @@
+from fastapi import FastAPI, Body
+from fastapi.middleware.cors import CORSMiddleware
+from pydantic import create_model
+
+
+from mcp import ClientSession, StdioServerParameters, types
+from mcp.client.stdio import stdio_client
+
+import argparse
+import sys
+from typing import Dict, Any
+
+import asyncio
+import uvicorn
+import json
+import os
+
+
+async def create_dynamic_endpoints(app: FastAPI, session: ClientSession):
+    tools_result = await session.list_tools()
+    tools = tools_result.tools
+
+    for tool in tools:
+        print(tool)
+        endpoint_name = tool.name
+        endpoint_description = tool.description
+        schema = tool.inputSchema
+
+        # Dynamically creating a Pydantic model for validation and openAPI coverage
+        model_fields = {}
+        required_fields = schema.get("required", [])
+
+        for param_name, param_schema in schema["properties"].items():
+            param_type = param_schema["type"]
+            param_desc = param_schema.get("description", "")
+            python_type = str  # default
+
+            if param_type == "string":
+                python_type = str
+            elif param_type == "integer":
+                python_type = int
+            elif param_type == "boolean":
+                python_type = bool
+            elif param_type == "number":
+                python_type = float
+            elif param_type == "object":
+                python_type = Dict[str, Any]
+            elif param_type == "array":
+                python_type = list
+            # Expand as needed. PRs welcome!
+
+            default_value = ... if param_name in required_fields else None
+            model_fields[param_name] = (
+                python_type,
+                Body(default_value, description=param_desc),
+            )
+
+        FormModel = create_model(f"{endpoint_name}_form_model", **model_fields)
+
+        def make_endpoint_func(endpoint_name: str, FormModel):
+            async def endpoint_func(form_data: FormModel):
+                args = form_data.model_dump()
+                print("Calling tool with arguments:", args)
+                print("Tool name:", endpoint_name)
+                result = await session.call_tool(endpoint_name, arguments=args)
+                return result
+
+            return endpoint_func
+
+        endpoint_func = make_endpoint_func(endpoint_name, FormModel)
+
+        # Add endpoint to FastAPI with tool descriptions
+        app.post(
+            f"/{endpoint_name}",
+            summary=endpoint_name.replace("_", " ").title(),
+            description=endpoint_description,
+        )(endpoint_func)
+
+
+async def run(host: str, port: int, server_cmd: list[str]):
+    server_params = StdioServerParameters(
+        command=server_cmd[0],
+        args=server_cmd[1:],
+        env={**os.environ},
+    )
+
+    # Open connection to MCP first:
+    async with stdio_client(server_params) as (read, write):
+        async with ClientSession(read, write) as session:
+            result = await session.initialize()
+
+            server_name = (
+                result.serverInfo.name
+                if hasattr(result, "serverInfo") and hasattr(result.serverInfo, "name")
+                else None
+            )
+
+            server_description = (
+                f"{server_name.capitalize()} MCP OpenAPI Proxy"
+                if server_name
+                else "Automatically generated API endpoints based on MCP tool schemas."
+            )
+
+            server_version = (
+                result.serverInfo.version
+                if hasattr(result, "serverInfo")
+                and hasattr(result.serverInfo, "version")
+                else "1.0"
+            )
+
+            app = FastAPI(
+                title=server_name if server_name else "MCP OpenAPI Proxy",
+                description=server_description,
+                version=server_version,
+            )
+
+            origins = ["*"]
+
+            app.add_middleware(
+                CORSMiddleware,
+                allow_origins=origins,
+                allow_credentials=True,
+                allow_methods=["*"],
+                allow_headers=["*"],
+            )
+
+            # Dynamic endpoint creation
+            await create_dynamic_endpoints(app, session)
+
+            config = uvicorn.Config(app=app, host=host, port=port, log_level="info")
+            server = uvicorn.Server(config)
+            await server.serve()
+
+
+def parse_args():
+    # Separate user args before and after "--"
+    if "--" not in sys.argv:
+        print("Usage: python main.py --host 0.0.0.0 --port 8000 -- your_mcp_command")
+        sys.exit(1)
+
+    split_index = sys.argv.index("--")
+    proxy_args = sys.argv[1:split_index]
+    mcp_args = sys.argv[split_index + 1 :]
+
+    parser = argparse.ArgumentParser(description="FastAPI MCP OpenAPI Proxy")
+    parser.add_argument("--host", type=str, default="0.0.0.0", help="Host to listen on")
+    parser.add_argument("--port", type=int, default=8000, help="Port to listen on")
+
+    args = parser.parse_args(proxy_args)
+
+    if not mcp_args:
+        print("Error: You must specify the MCP server command after '--'")
+        sys.exit(1)
+
+    return args.host, args.port, mcp_args
+
+
+if __name__ == "__main__":
+    host, port, server_cmd = parse_args()
+    asyncio.run(run(host, port, server_cmd))