Adding support for AWS IAM authentication for MSK

lib/fluent/plugin/out_rdkafka2.rb

@@ -101,6 +101,8 @@ class Fluent::Rdkafka2Output < Output
     config_param :unrecoverable_error_codes, :array, :default => ["topic_authorization_failed", "msg_size_too_large"],
                  :desc => 'Handle some of the error codes should be unrecoverable if specified'
 
+    config_param :aws_msk_region, :string, :default => nil, :desc => 'AWS region for MSK'
+
     config_section :buffer do
       config_set_default :chunk_keys, ["topic"]
     end
@@ -205,10 +207,17 @@ def add(level, message = nil)
           end
         end
       }
+      # HERE -----------------
       Rdkafka::Config.logger = log
       config = build_config
       @rdkafka = Rdkafka::Config.new(config)
 
+
+      if config[:"security.protocol"] == "sasl_ssl" && config[:"sasl.mechanisms"] == "OAUTHBEARER"
+        Rdkafka::Config.oauthbearer_token_refresh_callback = method(:refresh_token)
+      end
+      # HERE -----------------
+
       if @default_topic.nil?
         if @use_default_for_unknown_topic || @use_default_for_unknown_partition_error
           raise Fluent::ConfigError, "default_topic must be set when use_default_for_unknown_topic or use_default_for_unknown_partition_error is true"
@@ -289,13 +298,34 @@ def build_config
       config[:"sasl.password"] = @password if @password
       config[:"enable.idempotence"] = @idempotent if @idempotent
 
+      # sasl.mechnisms and security.protocol are set as rdkafka_options
       @rdkafka_options.each { |k, v|
         config[k.to_sym] = v
       }
 
       config
     end
 
+    def refresh_token(_config, _client_name)
+      print "refreshing token\n"
+      client = get_producer
+      signer = AwsMskIamSaslSigner::MSKTokenProvider.new(region: @aws_msk_region)
+      token = signer.generate_auth_token
+
+      if token
+        client.oauthbearer_set_token(
+          token: token.token,
+          lifetime_ms: token.expiration_time_ms,
+          principal_name: "kafka-cluster"
+        )
+      else
+        client.oauthbearer_set_token_failure(
+          "Failed to generate token."
+        )
+      end
+    end
+
+    # HERE -----------------
     def start
       if @share_producer
         @shared_producer = @rdkafka.producer
@@ -306,6 +336,7 @@ def start
 
       super
     end
+    # HERE -----------------
 
     def multi_workers_ready?
       true