feat(tvix/nar-bridge): send content-type headers r/8561

This prevents browsers from treating NARInfo and nix-cache-info paths as
a separate "Download", but just show it in plaintext.

Change-Id: If99abe20ef1d24e4fa86c055160861ca47aa81ce
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12267
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/tvix/nar-bridge/src/lib.rs b/tvix/nar-bridge/src/lib.rs
index 56b7e19a3cb0..79f9b7372245 100644
--- a/tvix/nar-bridge/src/lib.rs
+++ b/tvix/nar-bridge/src/lib.rs
@@ -1,7 +1,9 @@
 use axum::http::StatusCode;
+use axum::response::IntoResponse;
 use axum::routing::{head, put};
 use axum::{routing::get, Router};
 use lru::LruCache;
+use nix_compat::nix_http;
 use parking_lot::RwLock;
 use std::num::NonZeroUsize;
 use std::sync::Arc;
@@ -71,9 +73,12 @@ async fn four_o_four() -> Result<(), StatusCode> {
     Err(StatusCode::NOT_FOUND)
 }
 
-async fn nix_cache_info(priority: u64) -> String {
-    format!(
-        "StoreDir: /nix/store\nWantMassQuery: 1\nPriority: {}\n",
-        priority
+async fn nix_cache_info(priority: u64) -> impl IntoResponse {
+    (
+        [("Content-Type", nix_http::MIME_TYPE_CACHE_INFO)],
+        format!(
+            "StoreDir: /nix/store\nWantMassQuery: 1\nPriority: {}\n",
+            priority
+        ),
     )
 }