Add support for showing the Sidekiq Enterprise cluster leader process in Web UI, fixes mperham/sidekiq#2867

Ent-Changes.md

@@ -7,6 +7,7 @@ Please see [http://sidekiq.org/](http://sidekiq.org/) for more details and how t
 HEAD
 -------------
 
+- Show process "leader" tag on Busy page, requires Sidekiq 5.0.1 [#2867]
 - Capture custom metrics with the `save_history` API. [#2815]
 - Implement new `unique_util: 'start'` policy option. [#3471]
 

lib/sidekiq/api.rb

@@ -731,7 +731,7 @@ module Sidekiq
           next if info.nil?
 
           hash = Sidekiq.load_json(info)
-          yield Process.new(hash.merge('busy' => busy.to_i, 'beat' => at_s.to_f, 'quiet' => quiet))
+          yield Process.new(hash.merge('busy' => busy.to_i, 'beat' => at_s.to_f, 'quiet' => quiet)), leader
         end
       end
 
@@ -745,6 +745,18 @@ module Sidekiq
     def size
       Sidekiq.redis { |conn| conn.scard('processes') }
     end
+
+    # Returns the identity of the current cluster leader or "" if no leader.
+    # This is a Sidekiq Enterprise feature, will always return "" in Sidekiq
+    # or Sidekiq Pro.
+    def leader
+      @leader ||= begin
+        x = Sidekiq.redis {|c| c.get("dear-leader") }
+        # need a non-falsy value so we can memoize
+        x = "" unless x
+        x
+      end
+    end
   end
 
   #
@@ -779,6 +791,10 @@ module Sidekiq
       @attribs[key]
     end
 
+    def identity
+      self['identity']
+    end
+
     def quiet!
       signal('TSTP')
     end
@@ -807,9 +823,6 @@ module Sidekiq
       end
     end
 
-    def identity
-      self['identity']
-    end
   end
 
   ##

web/views/busy.erb

@@ -22,7 +22,7 @@
       <th><%= t('Busy') %></th>
       <th>&nbsp;</th>
     </thead>
-    <% processes.each do |process| %>
+    <% processes.each do |process,leader| %>
       <tr>
         <td class="box">
           <%= "#{process['hostname']}:#{process['pid']}" %>
@@ -31,7 +31,10 @@
             <span class="label label-info"><%= label %></span>
           <% end %>
           <% if process.stopping? %>
-            <span class="label label-danger">Quiet</span>
+            <span class="label label-danger">quiet</span>
+          <% end %>
+          <% if process.identity == leader %>
+            <span class="label label-warning">leader</span>
           <% end %>
           <br>
           <b><%= "#{t('Queues')}: " %></b>