APERTA-9087 Convert string to array and leave it as an array

config/initializers/sidekiq.rb

@@ -1,9 +1,12 @@
-sentinels = ENV['REDIS_SENTINELS']
+# YAML is part of the Ruby standard library and it is used here to convert
+# "['server1', 'server2', 'server3']" into ['server1', 'server2', 'server3']
+require 'yaml'
+sentinels = YAML::load(ENV['REDIS_SENTINELS'])
 Sidekiq.configure_server do |config|
   if sentinels.present?
-    sentinel_list = sentinels.join(',').map do |sentinel_host|
+    sentinel_list = sentinels.map do |sentinel_host|
       { host: sentinel_host, port: ENV['REDIS_PORT'] }
-    end.join(',')
+    end
     config.redis = {
       master_name: 'aperta',
       sentinels: sentinel_list,
@@ -31,9 +34,9 @@
 
 Sidekiq.configure_client do |config|
   if sentinels.present?
-    sentinel_list = sentinels.join(',').map do |sentinel_host|
+    sentinel_list = sentinels.map do |sentinel_host|
       { host: sentinel_host, port: ENV['REDIS_PORT'] }
-    end.join(',')
+    end
     config.redis = {
       master_name: 'aperta',
       sentinels: sentinel_list,