simple-web-app

commit d4a353f8d326e863fede66c19b068dbe222bce18
parent 151a4d25eb0556ee8495868e0ff5abd529c7b565
Author: Silas Brack <silasbrack@gmail.com>
Date:   Thu, 11 Jun 2026 14:55:03 +0200

fix: add X-Accel-Buffering header to SSE responses for nginx

Nginx buffers proxy responses by default, which prevents SSE
events from reaching the client in real-time. The /api/ location
had explicit proxy_buffering=off but the / location (serving the
app) did not. Adding X-Accel-Buffering: no to all SSE responses
tells nginx to disable buffering per-response.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Diffstat:
M
src/handlers/story.rs
 | 
13
+++++++++----
M
src/sse.rs
 | 
1
+

2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/src/handlers/story.rs b/src/handlers/story.rs
@@ -3,7 +3,7 @@ use std::convert::Infallible;
 use askama::Template;
 use axum::{
     extract::{Path, State},
-    response::{Html, Redirect, sse::{Event, Sse}},
+    response::{Html, IntoResponse, Redirect, Response, sse::{Event, Sse}},
     Form,
 };
 use axum_extra::extract::cookie::CookieJar;
@@ -407,7 +407,7 @@ pub async fn comments_stream(
     State(state): State<AppState>,
     jar: CookieJar,
     Path(story_id): Path<i64>,
-) -> Sse<impl tokio_stream::Stream<Item = Result<Event, Infallible>>> {
+) -> Response {
     let tokens = get_tokens_from_cookies(&jar);
     let (tx, rx) = tokio::sync::mpsc::channel::<Result<Event, Infallible>>(10);
 
@@ -492,10 +492,15 @@ pub async fn comments_stream(
     });
 
     let stream = tokio_stream::wrappers::ReceiverStream::new(rx);
-    Sse::new(stream).keep_alive(
+    let sse = Sse::new(stream).keep_alive(
         axum::response::sse::KeepAlive::new()
             .interval(std::time::Duration::from_secs(30)),
-    )
+    );
+    let mut response = sse.into_response();
+    response
+        .headers_mut()
+        .insert("X-Accel-Buffering", "no".parse().unwrap());
+    response
 }
 
 fn render_edit_error(story_id: i64, form: &EditForm, all_tags: &[trailbase::Category], error: &str) -> Html<String> {
diff --git a/src/sse.rs b/src/sse.rs
@@ -26,6 +26,7 @@ fn patch_elements_with_options(
         .status(StatusCode::OK)
         .header(header::CONTENT_TYPE, "text/event-stream")
         .header(header::CACHE_CONTROL, "no-cache")
+        .header("X-Accel-Buffering", "no")
         .body(Body::from(body))
         .unwrap()
 }