Add schema_registry_api_key to kafka input

docs/input-kafka.asciidoc

@@ -678,6 +678,15 @@ The schemas must follow a naming convention with the pattern <topic name>-value.
 Use either the Schema Registry config option or the
 <<plugins-{type}s-{plugin}-value_deserializer_class>> config option, but not both.
 
+[id="plugins-{type}s-{plugin}-schema_registry_api_key"]
+===== `schema_registry_api_key`
+
+* Value type is <<string,string>>
+* There is no default value for this setting.
+
+If schema registry is configured to validate client api key, this setting will send 
+the api key in all requests to the schema registry
+
 [id="plugins-{type}s-{plugin}-schema_registry_validation"]
 ===== `schema_registry_validation`
 

lib/logstash/inputs/kafka.rb

@@ -451,6 +451,9 @@ def create_consumer(client_id, group_instance_id)
         props.put(kafka::VALUE_DESERIALIZER_CLASS_CONFIG, Java::io.confluent.kafka.serializers.KafkaAvroDeserializer.java_class)
         serdes_config = Java::io.confluent.kafka.serializers.AbstractKafkaAvroSerDeConfig
         props.put(serdes_config::SCHEMA_REGISTRY_URL_CONFIG, schema_registry_url.uri.to_s)
+        if schema_registry_api_key
+          props.put("request.header.x-api-key", schema_registry_api_key.to_s)
+        end
         if schema_registry_proxy && !schema_registry_proxy.empty?
           props.put(serdes_config::PROXY_HOST, @schema_registry_proxy_host)
           props.put(serdes_config::PROXY_PORT, @schema_registry_proxy_port)

lib/logstash/plugin_mixins/kafka/avro_schema_registry.rb

@@ -20,6 +20,10 @@ def setup_schema_registry_config
       # instance of schema registry. If this option has value `value_deserializer_class` nor `topics_pattern` could be valued
       config :schema_registry_url, :validate => :uri
 
+      # Option to set the api key of the Schema Registry.
+      # This option permits to define an api key to be used with all schema registry requests either in header or as query parameter.
+      config :schema_registry_api_key, :validate => :string
+
       # Option to set the proxy of the Schema Registry.
       # This option permits to define a proxy to be used to reach the schema registry service instance.
       config :schema_registry_proxy, :validate => :uri
@@ -101,7 +105,11 @@ def check_for_schema_registry_connectivity_and_subjects
 
       client = Manticore::Client.new(options)
       begin
-        response = client.get(@schema_registry_url.uri.to_s + '/subjects').body
+        if schema_registry_api_key
+          response = client.get(@schema_registry_url.uri.to_s + '/subjects' + '?key=' + @schema_registry_apikey.to_s).body
+        else
+          response = client.get(@schema_registry_url.uri.to_s + '/subjects').body
+        end
       rescue Manticore::ManticoreException => e
         raise LogStash::ConfigurationError.new("Schema registry service doesn't respond, error: #{e.message}")
       end