move options validation in build_client

Author: colinsurprenant

lib/logstash/outputs/elasticsearch.rb

@@ -259,6 +259,14 @@ def config_init(params)
   end
 
   def build_client
+    # the following 3 options validation & setup methods are called inside build_client
+    # because they must be executed prior to building the client and logstash
+    # monitoring and management rely on directly calling build_client
+    # see https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/934#pullrequestreview-396203307
+    validate_authentication
+    fill_hosts_from_cloud_id
+    setup_hosts
+
     params["metric"] = metric
     if @proxy.eql?('')
       @logger.warn "Supplied proxy setting (proxy => '') has no effect"

lib/logstash/outputs/elasticsearch/common.rb

@@ -20,9 +20,6 @@ def register
       @stopping = Concurrent::AtomicBoolean.new(false)
       # To support BWC, we check if DLQ exists in core (< 5.4). If it doesn't, we use nil to resort to previous behavior.
       @dlq_writer = dlq_enabled? ? execution_context.dlq_writer : nil
-      validate_authentication
-      fill_hosts_from_cloud_id
-      setup_hosts # properly sets @hosts
       build_client
       setup_after_successful_connection
       check_action_validity