Aggregated Logging - Cannot connect to external Elasticsearch instance

Issue

After configured to connect external elasticsearch with following the document, failed to connect with below error messages.

$ oc logs logging-fluentd-xxxxx -f
2016-11-13 12:43:17 +1100 [info]: reading config file path="/etc/fluent/fluent.conf"
2016-11-13 12:43:31 +1100 [warn]: temporarily failed to flush the buffer. next_retry=2016-11-13 12:43:31 +1100 error_class="Fluent::ElasticsearchOutput::ConnectionFailure" error="Can not reach Elasticsearch cluster ({:host=>\"xxxxxxxxxx.ap-southeast-2.es.amazonaws.com\", :port=>443, :scheme=>\"https\", :user=>\"fluentd\", :password=>\"obfuscated\"})! No such file or directory -  (Errno::ENOENT)" plugin_id="object:1ce0184"
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:61:in `rescue in client'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:58:in `client'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:180:in `rescue in send'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:178:in `send'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:171:in `block in write'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:170:in `each'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluent-plugin-elasticsearch-1.3.0/lib/fluent/plugin/out_elasticsearch_dynamic.rb:170:in `write'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluentd-0.12.20/lib/fluent/buffer.rb:345:in `write_chunk'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluentd-0.12.20/lib/fluent/buffer.rb:324:in `pop'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluentd-0.12.20/lib/fluent/output.rb:329:in `try_flush'
  2016-11-13 12:43:31 +1100 [warn]: /usr/share/gems/gems/fluentd-0.12.20/lib/fluent/output.rb:140:in `run'