feat: add support for SSE level authentication (#2)

Support a new env var called API_ACCESS_TOKEN
Fix typo in README

README.md

@@ -56,11 +56,19 @@ Configure Claude Desktop to recognize the MCP server.
         "mcp-proxy": {
             "command": "mcp-proxy",
             "env": {
-                "SSE_URL": "http://example.io/sss"
+              "SSE_URL": "http://example.io/sse"
             }
-          }
         }
       }
     }
 
     ```
+
+## Advanced Configuration
+
+### Environment Variables
+
+| Name | Description |
+| ---- | ----------- |
+| SSE_URL | The MCP server SSE endpoint to connect to e.g. http://example.io/sse |
+| API_ACCESS_TOKEN | Added in the `Authorization` header of the HTTP request as a `Bearer` access token |

src/mcp_proxy/__init__.py

@@ -109,10 +109,14 @@ async def create_proxy_server(remote_app: ClientSession):
     return app
 
 
-async def run_sse_client(url: str):
+async def run_sse_client(url: str, api_access_token: str | None = None):
     from mcp.client.sse import sse_client
 
-    async with sse_client(url=url) as (read_stream, write_stream):
+    headers = {}
+    if api_access_token is not None:
+        headers["Authorization"] = f"Bearer {api_access_token}"
+
+    async with sse_client(url=url, headers=headers) as (read_stream, write_stream):
         async with ClientSession(read_stream, write_stream) as session:
             app = await create_proxy_server(session)
             async with server.stdio_server() as (read_stream, write_stream):

src/mcp_proxy/__main__.py

@@ -7,13 +7,14 @@ from . import run_sse_client
 
 logging.basicConfig(level=logging.DEBUG)
 SSE_URL: t.Final[str] = os.getenv("SSE_URL", "")
+API_ACCESS_TOKEN: t.Final[str] = os.getenv("API_ACCESS_TOKEN", None)
 
 if not SSE_URL:
     raise ValueError("SSE_URL environment variable is not set")
 
 
 def main():
-    asyncio.run(run_sse_client(SSE_URL))
+    asyncio.run(run_sse_client(SSE_URL, api_access_token=API_ACCESS_TOKEN))
 
 
 if __name__ == "__main__":