Add a plugin for HipChat notification

This plugin sends notification of build failure or success to a
HipChat room, if the status differs from the last build.

The plugin can be configured by adding one or more of these stanzas to
hydra.conf:

  <hipchat>
    jobs = (patchelf|nixops):.*:.*
    room = 1234
    token = 39ab2198fe...
  </hipchat>

Here "jobs" is a regular expression against which the fully qualified
job name of the build is matched (so for instance
"nixops:master:tarball" will match the stanza above).

release.nix

@@ -76,6 +76,8 @@ rec {
             DigestSHA1
             EmailSender
             FileSlurp
+            LWP
+            LWPProtocolHttps
             IOCompress
             IPCRun
             JSONXS

src/lib/Hydra/Plugin/HipChatNotification.pm

@@ -0,0 +1,71 @@
+package Hydra::Plugin::HipChatNotification;
+
+use strict;
+use parent 'Hydra::Plugin';
+use LWP::UserAgent;
+use Hydra::Helper::CatalystUtils;
+
+sub buildFinished {
+    my ($self, $build, $dependents) = @_;
+
+    my $cfg = $self->{config}->{hipchat};
+    my @config = ref $cfg eq "ARRAY" ? @$cfg : ($cfg);
+
+    my $baseurl = $self->{config}->{'base_uri'} || "http://localhost:3000";
+
+    # Figure out to which rooms to send notification.  For each email
+    # room, we send one aggregate message.
+    my %rooms;
+    foreach my $b ($build, @{$dependents}) {
+        my $prevBuild = getPreviousBuild($b);
+        my $jobName = showJobName $b;
+
+        foreach my $room (@config) {
+            next unless $jobName =~ /^$room->{jobs}$/;
+
+            # If build is cancelled or aborted, do not send email.
+            next if $b->buildstatus == 4 || $b->buildstatus == 3;
+
+            # If there is a previous (that is not cancelled or aborted) build
+            # with same buildstatus, do not send email.
+            next if defined $prevBuild && ($b->buildstatus == $prevBuild->buildstatus);
+
+            $rooms{$room->{room}} //= { room => $room, builds => [] };
+            push @{$rooms{$room->{room}}->{builds}}, $b;
+        }
+    }
+
+    # Send a message to each room.
+    foreach my $roomId (keys %rooms) {
+        my $room = $rooms{$roomId};
+        my @deps = grep { $_->id != $build->id } @{$room->{builds}};
+
+        my $imgBase = "http://hydra.nixos.org";
+        my $img =
+            $build->buildstatus == 0 ? "$imgBase/static/images/checkmark_16.png" :
+            $build->buildstatus == 2 ? "$imgBase/static/images/dependency_16.png" :
+            $build->buildstatus == 4 ? "$imgBase/static/images/cancelled_16.png" :
+            "$imgBase/static/images/error_16.png";
+
+        my $msg = "";
+        $msg .= "<img src='$img'/> ";
+        $msg .= "Job <a href='$baseurl/job/${\$build->project->name}/${\$build->jobset->name}/${\$build->job->name}'>${\showJobName($build)}</a>";
+        $msg .= " (and ${\scalar @deps} others)" if scalar @deps > 0;
+        $msg .= ": <a href='$baseurl/build/${\$build->id}'>" . showStatus($build) . "</a>";
+
+        print STDERR "sending hipchat notification to room $roomId: $msg\n";
+
+        my $ua = LWP::UserAgent->new();
+        my $resp = $ua->post('https://api.hipchat.com/v1/rooms/message?format=json&auth_token=' . $room->{room}->{token}, {
+            room_id => $roomId,
+            from => 'Hydra',
+            message => $msg,
+            message_format => 'html',
+            notify => 0,
+            color => $build->buildstatus == 0 ? 'green' : 'red' });
+
+        print STDERR $resp->status_line, ": ", $resp->decoded_content,"\n" if !$resp->is_success;
+    }
+}
+
+1;