* Quick hack to allow viewing of dependency graphs (via nix-store -q

--graph).  Maybe I should use SVG, since the generated PNGs tend to
  be huge.

src/Hydra/lib/Hydra/Controller/Build.pm

@@ -34,6 +34,7 @@ sub view_build : Chained('build') PathPart('') Args(0) {
     $c->stash->{template} = 'build.tt';
     $c->stash->{curTime} = time;
     $c->stash->{available} = isValidPath $build->outpath;
+    $c->stash->{drvAvailable} = isValidPath $build->drvpath;
 
     if (!$build->finished && $build->schedulingInfo->busy) {
         my $logfile = $build->schedulingInfo->logfile;
@@ -88,7 +89,7 @@ sub download : Chained('build') PathPart('download') {
     my $product = $c->stash->{build}->buildproducts->find({productnr => $productnr});
     notFound($c, "Build doesn't have a product $productnr.") if !defined $product;
 
-    error($c, "Product " . $product->path . " has disappeared.") unless -e $product->path;
+    notFound($c, "Product " . $product->path . " has disappeared.") unless -e $product->path;
 
     # Security paranoia.
     foreach my $elem (@path) {
@@ -111,6 +112,36 @@ sub download : Chained('build') PathPart('download') {
 }
 
 
+sub runtimedeps : Chained('build') PathPart('runtime-deps') {
+    my ($self, $c) = @_;
+    
+    my $build = $c->stash->{build};
+    
+    notFound($c, "Path " . $build->outpath . " is no longer available.")
+        unless isValidPath($build->outpath);
+    
+    $c->stash->{current_view} = 'Hydra::View::NixDepGraph';
+    $c->stash->{storePaths} = [$build->outpath];
+    
+    $c->response->content_type('image/png'); # !!!
+}
+
+
+sub buildtimedeps : Chained('build') PathPart('buildtime-deps') {
+    my ($self, $c) = @_;
+    
+    my $build = $c->stash->{build};
+    
+    notFound($c, "Path " . $build->drvpath . " is no longer available.")
+        unless isValidPath($build->drvpath);
+    
+    $c->stash->{current_view} = 'Hydra::View::NixDepGraph';
+    $c->stash->{storePaths} = [$build->drvpath];
+    
+    $c->response->content_type('image/png'); # !!!
+}
+
+
 sub nix : Chained('build') PathPart('nix') CaptureArgs(0) {
     my ($self, $c) = @_;
 

src/Hydra/lib/Hydra/View/NixDepGraph.pm

@@ -0,0 +1,24 @@
+package Hydra::View::NixDepGraph;
+
+use strict;
+use base qw/Catalyst::View/;
+use IO::Pipe;
+
+sub process {
+    my ($self, $c) = @_;
+    
+    $c->response->content_type('image/png');
+
+    my @storePaths = @{$c->stash->{storePaths}};
+
+    open(OUTPUT, "nix-store --query --graph @storePaths | dot -Tpng -Gbgcolor=transparent |");
+
+    my $fh = new IO::Handle;
+    $fh->fdopen(fileno(OUTPUT), "r") or die;
+
+    $c->response->body($fh);
+    
+    return 1;
+}
+
+1;

src/Hydra/root/build.tt

@@ -86,11 +86,21 @@
   </tr>
   <tr>
     <th>Derivation store path:</th>
-    <td><tt>[% build.drvpath %]</tt></td>
+    <td>
+      <tt>[% build.drvpath %]</tt>
+      [% IF drvAvailable %]
+        (<a href="[% c.uri_for('/build' build.id 'buildtime-deps') %]">build-time dependencies</a>)
+      [% END %]
+    </td>
   </tr>
   <tr>
     <th>Output store path:</th>
-    <td><tt>[% build.outpath %]</tt></td>
+    <td>
+      <tt>[% build.outpath %]</tt>
+      [% IF available %]
+        (<a href="[% c.uri_for('/build' build.id 'runtime-deps') %]">runtime dependencies</a>)
+      [% END %]
+    </td>
   </tr>
   [% IF build.finished %]
   <tr>