* Generate manifests on demand. Next step: generate NAR archives on

demand, then we can have channel support and one-click installs in
  Hydra.

src/Hydra/lib/Hydra/Controller/Root.pm

@@ -707,6 +707,17 @@ sub closure :Local {
 }
 
 
+sub manifest :Local {
+    my ($self, $c, $buildId) = @_;
+
+    my $build = getBuild($c, $buildId);
+    return error($c, "Build with ID $buildId doesn't exist.") if !defined $build;
+
+    $c->stash->{current_view} = 'Hydra::View::NixManifest';
+    $c->stash->{storePath} = $build->outpath;
+}
+
+
 sub end : ActionClass('RenderView') {}
 
 

src/Hydra/lib/Hydra/View/NixManifest.pm

@@ -0,0 +1,56 @@
+package Hydra::View::NixManifest;
+
+use strict;
+use base qw/Catalyst::View/;
+use IO::Pipe;
+use IPC::Run;
+use POSIX qw(dup2);
+
+sub captureStdoutStderr {
+    my $stdin = ""; my $stdout; my $stderr;
+    my $res = IPC::Run::run(\@_, \$stdin, \$stdout, \$stderr);
+    return ($res, $stdout, $stderr);
+}
+
+    
+sub process {
+    my ($self, $c) = @_;
+
+    my $storePath = $c->stash->{storePath};
+    
+    $c->response->content_type('text/x-nix-manifest');
+
+    my @paths = split '\n', `nix-store --query --requisites $storePath`
+        or die "cannot query dependencies of `$storePath': $?";
+
+    my $manifest =
+        "version {\n" .
+        "  ManifestVersion: 3\n" .
+        "}\n";
+    
+    foreach my $path (@paths) {
+        my ($res, $out, $err) = captureStdoutStderr(qw(nix-store --query --references), $path);
+        die "cannot query references of `$path':\n$err" unless $res;
+        my @refs = split '\n', $out;
+        
+        my $hash = `nix-store --query --hash $path`
+            or die "cannot query hash of `$path': $?";
+        chomp $hash;
+
+        my $url = $c->uri_for('/nar' . $path);
+        
+        $manifest .=
+            "{\n" .
+            "  StorePath: $path\n" .
+            "  NarURL: $url\n" .
+            "  References: @refs\n" .
+            "  Hash: $hash\n" .
+            "}\n";
+    }
+
+    $c->response->body($manifest);
+
+    return 1;
+}
+
+1;