From 42fbde03835b90c52e630ed0c2211217e2f77181 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 18 Oct 2017 12:48:31 +0200
Subject: [PATCH] Use "nix cat-store" to serve files from the Nix store

This makes downloading/viewing build results work with binary cache
stores. For good performance, this should be used in conjunction with
https://github.com/NixOS/nix/commit/ca580bec35ea4d1984e36864158d7be99cfcb34b,
i.e. you should set store_uri to something like

  s3://my-cache?local-nar-cache=/tmp/nar-cache

to cache NARs between requests.
---
 src/lib/Hydra/Controller/Build.pm | 40 ++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/src/lib/Hydra/Controller/Build.pm b/src/lib/Hydra/Controller/Build.pm
index f3b6f49f..b96d0f2f 100644
--- a/src/lib/Hydra/Controller/Build.pm
+++ b/src/lib/Hydra/Controller/Build.pm
@@ -204,8 +204,6 @@ sub download : Chained('buildChain') PathPart {
     }
     my $storePath = $1;
 
-    notFound($c, "File " . $product->path . " does not exist.") unless -e $product->path;
-
     return $c->res->redirect(defaultUriForProduct($self, $c, $product, @path))
         if scalar @path == 0 && ($product->name || $product->defaultpath);
 
@@ -221,22 +219,32 @@ sub download : Chained('buildChain') PathPart {
     my $path = $product->path;
     $path .= "/" . join("/", @path) if scalar @path > 0;
 
-    # Make sure the file is in the Nix store.
-    $path = checkPath($self, $c, $path);
+    if (isLocalStore) {
 
-    # If this is a directory but no "/" is attached, then redirect.
-    if (-d $path && substr($c->request->uri, -1) ne "/") {
-        return $c->res->redirect($c->request->uri . "/");
+        notFound($c, "File " . $product->path . " does not exist.") unless -e $product->path;
+
+        # Make sure the file is in the Nix store.
+        $path = checkPath($self, $c, $path);
+
+        # If this is a directory but no "/" is attached, then redirect.
+        if (-d $path && substr($c->request->uri, -1) ne "/") {
+            return $c->res->redirect($c->request->uri . "/");
+        }
+
+        $path = "$path/index.html" if -d $path && -e "$path/index.html";
+
+        notFound($c, "File $path does not exist.") if !-e $path;
+
+        notFound($c, "Path $path is a directory.") if -d $path;
+
+        $c->serve_static_file($path);
+        $c->response->headers->last_modified($c->stash->{build}->stoptime);
+
+    } else {
+        $c->stash->{'plain'} = { data => readNixFile($path) };
+        $c->response->content_type('application/octet-stream');
+        $c->forward('Hydra::View::Plain');
     }
-
-    $path = "$path/index.html" if -d $path && -e "$path/index.html";
-
-    notFound($c, "File $path does not exist.") if !-e $path;
-
-    notFound($c, "Path $path is a directory.") if -d $path;
-
-    $c->serve_static_file($path);
-    $c->response->headers->last_modified($c->stash->{build}->stoptime);
 }