From d7f4b950ce6e966ed1b410e03d48fe96bc036e73 Mon Sep 17 00:00:00 2001
From: Ruben Fiszel <ruben@windmill.dev>
Date: Thu, 26 Mar 2026 12:42:02 +0000
Subject: [PATCH] fix: pass pre-bound TcpListener to run_server to fix Windows
 CI test race (#8542)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 backend/src/main.rs                    |  5 ++++-
 backend/windmill-api/src/lib.rs        | 10 +++++-----
 backend/windmill-test-utils/src/lib.rs |  7 +++----
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/backend/src/main.rs b/backend/src/main.rs
index ad5b9e14b8..4fe22c517f 100644
--- a/backend/src/main.rs
+++ b/backend/src/main.rs
@@ -1099,6 +1099,9 @@ Windmill Community Edition {GIT_VERSION}
         }
 
         let addr = SocketAddr::from((server_bind_address, port));
+        let listener = tokio::net::TcpListener::bind(addr)
+            .await
+            .context("binding main windmill server")?;
 
         let (base_internal_tx, base_internal_rx) = tokio::sync::oneshot::channel::<String>();
 
@@ -1232,7 +1235,7 @@ Windmill Community Edition {GIT_VERSION}
                         db.clone(),
                         index_reader,
                         log_index_reader,
-                        addr,
+                        listener,
                         server_killpill_rx,
                         base_internal_tx,
                         server_mode,
diff --git a/backend/windmill-api/src/lib.rs b/backend/windmill-api/src/lib.rs
index 65ba4cad15..15a674ea37 100644
--- a/backend/windmill-api/src/lib.rs
+++ b/backend/windmill-api/src/lib.rs
@@ -45,8 +45,8 @@ use windmill_common::global_settings::EMAIL_DOMAIN_SETTING;
 use windmill_common::worker::HUB_CACHE_DIR;
 
 use std::fs::DirBuilder;
+use std::sync::Arc;
 use std::time::Duration;
-use std::{net::SocketAddr, sync::Arc};
 use tokio::sync::RwLock;
 use tower::ServiceBuilder;
 use tower_cookies::CookieManagerLayer;
@@ -326,7 +326,7 @@ pub async fn run_server(
     db: DB,
     job_index_reader: Option<IndexReader>,
     log_index_reader: Option<ServiceLogIndexReader>,
-    addr: SocketAddr,
+    listener: tokio::net::TcpListener,
     mut killpill_rx: tokio::sync::broadcast::Receiver<()>,
     port_tx: tokio::sync::oneshot::Sender<String>,
     server_mode: bool,
@@ -412,6 +412,9 @@ pub async fn run_server(
                     auth_cache: auth_cache.clone(),
                     base_internal_url: _base_internal_url.clone(),
                 });
+                let addr = listener
+                    .local_addr()
+                    .unwrap_or_else(|_| std::net::SocketAddr::from(([127, 0, 0, 1], 0)));
                 if let Err(err) = smtp_server.start_listener_thread(addr).await {
                     tracing::error!("Error starting SMTP server: {err:#}");
                 }
@@ -452,9 +455,6 @@ pub async fn run_server(
         health::start_health_check_loop(db.clone(), killpill_rx.resubscribe());
     }
 
-    let listener = tokio::net::TcpListener::bind(addr)
-        .await
-        .context("binding main windmill server")?;
     let port = listener.local_addr().map(|x| x.port()).unwrap_or(8000);
     let ip = listener
         .local_addr()
diff --git a/backend/windmill-test-utils/src/lib.rs b/backend/windmill-test-utils/src/lib.rs
index ef2bf66513..d9e22eaa84 100644
--- a/backend/windmill-test-utils/src/lib.rs
+++ b/backend/windmill-test-utils/src/lib.rs
@@ -97,14 +97,13 @@ impl ApiServer {
     async fn start_inner(db: Pool<Postgres>, agent_mode: bool) -> anyhow::Result<Self> {
         let (tx, rx) = tokio::sync::broadcast::channel::<()>(1);
 
-        let sock = tokio::net::TcpListener::bind("127.0.0.1:0")
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
             .await
             .map_err(|e| anyhow::anyhow!("failed to bind TCP listener: {}", e))?;
 
-        let addr = sock
+        let addr = listener
             .local_addr()
             .map_err(|e| anyhow::anyhow!("failed to get local address: {}", e))?;
-        drop(sock);
         let (port_tx, _port_rx) = tokio::sync::oneshot::channel::<String>();
         let name = next_worker_name();
         tracing::info!("starting api server for name={name}");
@@ -112,7 +111,7 @@ impl ApiServer {
             db.clone(),
             None,
             None,
-            addr,
+            listener,
             rx,
             port_tx,
             agent_mode,