fix(mcp): use computed base_internal_url instead of static default (#7701)

* fix(mcp): use computed base_internal_url instead of static default

Pass the actual base_internal_url (computed from the runtime port) to
the MCP backend instead of using the static BASE_INTERNAL_URL which
defaults to http://localhost:8000. This fixes internal API calls when
the server runs on a non-default port.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix

* remove BASE_INTERNAL_URL

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

backend/windmill-api/src/lib.rs

@@ -419,7 +419,7 @@ pub async fn run_server(
         if server_mode || mcp_mode {
             use mcp::add_www_authenticate_header;
             let (mcp_router, mcp_cancellation_token) =
-                setup_mcp_server(db.clone(), user_db).await?;
+                setup_mcp_server(db.clone(), user_db, _base_internal_url.clone()).await?;
             // Apply middleware: auth check inside WWW-Authenticate wrapper so 401s get the header
             let mcp_router = mcp_router
                 .route_layer(from_extractor::<ApiAuthed>())

backend/windmill-api/src/mcp/core.rs

@@ -75,11 +75,12 @@ impl McpAuth for ApiAuthed {
 pub struct WindmillBackend {
     pub db: DB,
     pub user_db: UserDB,
+    pub base_internal_url: String,
 }
 
 impl WindmillBackend {
-    pub fn new(db: DB, user_db: UserDB) -> Self {
-        Self { db, user_db }
+    pub fn new(db: DB, user_db: UserDB, base_internal_url: String) -> Self {
+        Self { db, user_db, base_internal_url }
     }
 }
 
@@ -355,9 +356,7 @@ impl McpBackend for WindmillBackend {
         let query_string = build_query_string(args_map, &endpoint_tool.query_params_schema);
         let full_url = format!(
             "{}/api{}{}",
-            windmill_common::BASE_INTERNAL_URL.as_str(),
-            path_template,
-            query_string
+            self.base_internal_url, path_template, query_string
         );
 
         // Prepare request body
@@ -462,11 +461,12 @@ pub async fn add_www_authenticate_header(
 pub async fn setup_mcp_server(
     db: DB,
     user_db: UserDB,
+    base_internal_url: String,
 ) -> anyhow::Result<(Router, CancellationToken)> {
     let cancellation_token = CancellationToken::new();
     let session_manager = Arc::new(LocalSessionManager::default());
 
-    let backend = WindmillBackend::new(db, user_db);
+    let backend = WindmillBackend::new(db, user_db, base_internal_url);
     let runner = Runner::new(backend);
 
     let service_config = StreamableHttpServerConfig {

backend/windmill-common/src/lib.rs

@@ -152,8 +152,6 @@ lazy_static::lazy_static! {
 
     pub static ref BASE_URL: Arc<RwLock<String>> = Arc::new(RwLock::new("".to_string()));
     pub static ref IS_READY: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(false);
-
-    pub static ref BASE_INTERNAL_URL: String = std::env::var("BASE_INTERNAL_URL").unwrap_or("http://localhost:8000".to_string());
     pub static ref HUB_BASE_URL: Arc<RwLock<String>> = Arc::new(RwLock::new(DEFAULT_HUB_BASE_URL.to_string()));
 
 

backend/windmill-common/src/worker.rs

@@ -35,7 +35,7 @@ use crate::{
     indexer::TantivyIndexerSettings,
     server::Smtp,
     utils::{merge_nested_raw_values_to_array, merge_raw_values_to_array},
-    KillpillSender, BASE_INTERNAL_URL, DB,
+    KillpillSender, DB,
 };
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Default)]
@@ -274,6 +274,8 @@ pub const ROOT_CACHE_NOMOUNT_DIR: &str = concatcp!(TMP_DIR, "/cache_nomount/");
 
 pub static MIN_VERSION_IS_LATEST: AtomicBool = AtomicBool::new(false);
 
+const DEFAULT_BASE_INTERNAL_URL: &str = "http://localhost:8000";
+
 #[derive(Clone)]
 pub struct HttpClient {
     pub client: ClientWithMiddleware,
@@ -298,7 +300,7 @@ impl HttpClient {
         let base_url = self
             .base_internal_url
             .clone()
-            .unwrap_or(BASE_INTERNAL_URL.clone().to_owned());
+            .unwrap_or(DEFAULT_BASE_INTERNAL_URL.to_owned());
 
         let response_builder = self.client.post(format!("{}{}", base_url, url)).json(body);
 
@@ -327,7 +329,7 @@ impl HttpClient {
         let base_url = self
             .base_internal_url
             .clone()
-            .unwrap_or(BASE_INTERNAL_URL.clone().to_owned());
+            .unwrap_or(DEFAULT_BASE_INTERNAL_URL.to_owned());
 
         let response = self
             .client
@@ -1226,7 +1228,6 @@ pub fn get_windmill_memory_usage() -> Option<i64> {
     }
 }
 
-
 #[derive(Serialize, Deserialize)]
 pub enum PingType {
     Initial,