diff --git a/src/lib/Hydra/Plugin/SlackNotification.pm b/src/lib/Hydra/Plugin/SlackNotification.pm
index 96933c51..a09fbe03 100644
--- a/src/lib/Hydra/Plugin/SlackNotification.pm
+++ b/src/lib/Hydra/Plugin/SlackNotification.pm
@@ -7,6 +7,53 @@ use LWP::UserAgent;
 use Hydra::Helper::CatalystUtils;
 use JSON;
 
+=head1 NAME
+
+SlackNotification - hydra-notify plugin for sending Slack notifications about
+build results
+
+=head1 DESCRIPTION
+
+This plugin reports build statuses to various Slack channels. One can configure
+which builds are reported to which channels, and whether reports should be on
+state change (regressions and improvements), or for each build.
+
+=head1 CONFIGURATION
+
+The module is configured using the C<slack> block in Hydra's config file. There
+can be multiple such blocks in the config file, each configuring different (or
+even the same) set of builds and how they report to Slack channels.
+
+The following entries are recognized in the C<slack> block:
+
+=over 4
+
+=item jobs
+
+A pattern for job names. All builds whose job name matches this pattern will
+emit a message to the designated Slack channel (see C<url>). The pattern will
+match the whole name, thus leaving this field empty will result in no
+notifications being sent. To match on all builds, use C<.*>.
+
+=item url
+
+The URL to a L<Slack incoming webhook|https://api.slack.com/messaging/webhooks>.
+
+Slack administrators have to prepare one incoming webhook for each channel. This
+URL should be treated as secret, as anyone knowing the URL could post a message
+to the Slack workspace (or more precisely, the channel behind it).
+
+=item force
+
+(Optional) An I<integer> indicating whether to report on every build or only on
+changes in the status. If not provided, defaults to 0, that is, sending reports
+only when build status changes from success to failure, and vice-versa. Any
+other value results in reporting on every build.
+
+=back
+
+=cut
+
 sub isEnabled {
     my ($self) = @_;
     return defined $self->{config}->{slack};
@@ -40,20 +87,32 @@ sub buildFinished {
     # we send one aggregate message.
     my %channels;
     foreach my $b ($build, @{$dependents}) {
-        my $prevBuild = getPreviousBuild($b);
         my $jobName = showJobName $b;
+        my $buildStatus = $b->buildstatus;
+        my $cancelledOrAborted = $buildStatus == 4 || $buildStatus == 3;
+
+        my $prevBuild = getPreviousBuild($b);
+        my $sameAsPrevious = defined $prevBuild && ($buildStatus == $prevBuild->buildstatus);
+        my $prevBuildStatus = (defined $prevBuild) ? $prevBuild->buildstatus : -1;
+        my $prevBuildId = (defined $prevBuild) ? $prevBuild->id : -1;
+
+        print STDERR "SlackNotification_Debug job name $jobName status $buildStatus (previous: $prevBuildStatus from $prevBuildId)\n";
 
         foreach my $channel (@config) {
-            my $force = $channel->{force};
             next unless $jobName =~ /^$channel->{jobs}$/;
 
-            # If build is cancelled or aborted, do not send email.
-            next if ! $force && ($b->buildstatus == 4 || $b->buildstatus == 3);
+            my $force = $channel->{force};
+
+            print STDERR "SlackNotification_Debug found match with '$channel->{jobs}' with force=$force\n";
+
+            # If build is cancelled or aborted, do not send Slack notification.
+            next if ! $force && $cancelledOrAborted;
 
             # If there is a previous (that is not cancelled or aborted) build
-            # with same buildstatus, do not send email.
-            next if ! $force && defined $prevBuild && ($b->buildstatus == $prevBuild->buildstatus);
+            # with same buildstatus, do not send Slack notification.
+            next if ! $force && $sameAsPrevious;
 
+            print STDERR "SlackNotification_Debug adding $jobName to the report list\n";
             $channels{$channel->{url}} //= { channel => $channel, builds => [] };
             push @{$channels{$channel->{url}}->{builds}}, $b;
         }
@@ -93,6 +152,8 @@ sub buildFinished {
             $text .= join(" or ", scalar @x > 1 ? join(", ", @x[0..scalar @x - 2]) : (), $x[-1]);
         }
 
+        print STDERR "SlackNotification_Debug POSTing to url ending with: ${\substr $url, -8}\n";
+
         my $msg =
         { attachments =>
           [{ fallback => "Job " . showJobName($build) . " build number " . $build->id . ": " . showStatus($build),