From 6ca0eec1075053d4e97b35dfbf8ededcdcd1791a Mon Sep 17 00:00:00 2001
From: Hengfei Yang <hengfei.yang@gmail.com>
Date: Mon, 17 Aug 2026 11:44:34 +0000
Subject: [PATCH] fix: MCP tool calls return 404 when ZO_BASE_URI is set
 (#13844)
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Fixes #13845

## What changed

The MCP shared HTTP client (used to execute tool calls against the local
REST API) now includes `ZO_BASE_URI` in its base URL:
`http://localhost:{port}{base_uri}` instead of
`http://localhost:{port}`.

## Why

When `ZO_BASE_URI` is set (e.g. `/abc`), all HTTP routes are mounted
under that prefix. The MCP endpoint itself was reachable (`POST
/abc/api/default/mcp` → 200), but every tool execution failed: the
internal client sent requests to the unprefixed path and got a 404.

```
INFO rmcp_openapi::http_client: Final URL: http://localhost:5080/api/default/streams
INFO config::axum::middlewares::access_log: 127.0.0.1 "GET /api/default/streams HTTP/1.1" 404 ...
```

## Notes for reviewers

- `cfg.common.base_uri` is already normalized at config load to have no
trailing slash (empty when unset), so the empty-prefix behavior is
unchanged.
- The join semantics are safe for path-prefixed base URLs:
rmcp-openapi's `with_base_url` appends a trailing slash and `build_url`
strips the tool path's leading slash before `Url::join`, covered by the
crate's `test_build_url_with_base_url_containing_path`. So `/abc` +
`/api/{org}/streams` → `/abc/api/{org}/streams`.
- The other `localhost:5080` occurrence in `tools.rs` is a test-only
mock client; the OAuth protected-resource metadata handler already
includes `base_uri`.
- `cargo check -p openobserve-mcp` and `cargo test -p openobserve-mcp`
pass.
---
 src/mcp/src/tools.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/mcp/src/tools.rs b/src/mcp/src/tools.rs
index 6fb529567a..0b53c85452 100644
--- a/src/mcp/src/tools.rs
+++ b/src/mcp/src/tools.rs
@@ -360,8 +360,12 @@ pub fn init_mcp_tools(api: &OpenApi) -> Result<()> {
     let spec = rmcp_openapi::Spec::from_value(api_json)?;
 
     let zo_config = config::get_config();
-    let base_url = url::Url::parse(&format!("http://localhost:{}", zo_config.http.port))
-        .map_err(|e| anyhow::anyhow!("Invalid base URL: {e}"))?;
+    // Include ZO_BASE_URI so tool calls hit the routes actually mounted under it
+    let base_url = url::Url::parse(&format!(
+        "http://localhost:{}{}",
+        zo_config.http.port, zo_config.common.base_uri
+    ))
+    .map_err(|e| anyhow::anyhow!("Invalid base URL: {e}"))?;
 
     // Set default headers including x-o2-mcp for MCP-initiated calls
     let mut default_headers = reqwest::header::HeaderMap::new();