feat(out_kafka2): adds support for AWS IAM authentication to MSK usin…

…g long lived credentials

This commit adds support for AWS IAM authentication using long lived
credentials (access key id and secret access keys). To support AWS
assume role and STS, we will need to wait for upstream's `ruby-kafka`
library support.

We will need to bump `ruby-kafka` to 1.5.0 in order to support this
feature.

README.md

@@ -212,6 +212,16 @@ If `ruby-kafka` doesn't fit your kafka environment, check `rdkafka2` plugin inst
       partitioner_hash_function (enum) (crc32|murmur2) :default => 'crc32'
       share_producer        (bool)   :default => false
 
+      # If you intend to rely on AWS IAM auth to MSK with long lived credentials
+      # https://docs.aws.amazon.com/msk/latest/developerguide/iam-access-control.html
+      #
+      # For AWS STS support, see status in
+      # - https://github.com/zendesk/ruby-kafka/issues/944
+      # - https://github.com/zendesk/ruby-kafka/pull/951
+      sasl_aws_msk_iam_access_key_id (string) :default => nil
+      sasl_aws_msk_iam_secret_key_id (string) :default => nil
+      sasl_aws_msk_iam_aws_region    (string) :default => nil
+
       <format>
         @type (json|ltsv|msgpack|attr:<record name>|<formatter name>) :default => json
       </format>

fluent-plugin-kafka.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency "fluentd", [">= 0.10.58", "< 2"]
   gem.add_dependency 'ltsv'
-  gem.add_dependency 'ruby-kafka', '>= 1.4.0', '< 2'
+  gem.add_dependency 'ruby-kafka', '>= 1.5.0', '< 2'
   gem.add_development_dependency "rake", ">= 0.9.2"
   gem.add_development_dependency "test-unit", ">= 3.0.8"
   gem.add_development_dependency "test-unit-rr", "~> 1.0"

lib/fluent/plugin/kafka_plugin_util.rb

@@ -1,5 +1,18 @@
 module Fluent
   module KafkaPluginUtil
+    module AwsIamSettings
+      def self.included(klass)
+        klass.instance_eval do
+          config_param :sasl_aws_msk_iam_access_key_id, :string, :default => nil, secret: true,
+                       desc: "AWS access key Id for IAM authentication to MSK."
+          config_param :sasl_aws_msk_iam_secret_key_id, :string, :default => nil, secret: true,
+                       desc: "AWS access key secret for IAM authentication to MSK."
+          config_param :sasl_aws_msk_iam_aws_region, :string, :default => nil,
+                       desc: "AWS region for IAM authentication to MSK."
+        end
+      end
+    end
+
     module SSLSettings
       def self.included(klass)
         klass.instance_eval {

lib/fluent/plugin/out_kafka2.rb

@@ -95,6 +95,7 @@ class Fluent::Kafka2Output < Output
       config_set_default :@type, 'json'
     end
 
+    include Fluentd::KafkaPluginUtil::AwsIamSettings
     include Fluent::KafkaPluginUtil::SSLSettings
     include Fluent::KafkaPluginUtil::SaslSettings
 
@@ -113,6 +114,7 @@ def initialize
     def refresh_client(raise_error = true)
       begin
         logger = @get_kafka_client_log ? log : nil
+        use_long_lived_aws_credentials = @sasl_aws_msk_iam_access_key_id != nil && @sasl_aws_msk_iam_secret_key_id != nil
         if @scram_mechanism != nil && @username != nil && @password != nil
           @kafka = Kafka.new(seed_brokers: @seed_brokers, client_id: @client_id, logger: logger, connect_timeout: @connect_timeout, socket_timeout: @socket_timeout, ssl_ca_cert_file_path: @ssl_ca_cert,
                              ssl_client_cert: read_ssl_file(@ssl_client_cert), ssl_client_cert_key: read_ssl_file(@ssl_client_cert_key), ssl_client_cert_chain: read_ssl_file(@ssl_client_cert_chain),
@@ -125,6 +127,26 @@ def refresh_client(raise_error = true)
                              ssl_ca_certs_from_system: @ssl_ca_certs_from_system, sasl_plain_username: @username, sasl_plain_password: @password, sasl_over_ssl: @sasl_over_ssl,
                              ssl_verify_hostname: @ssl_verify_hostname, resolve_seed_brokers: @resolve_seed_brokers,
                              partitioner: Kafka::Partitioner.new(hash_function: @partitioner_hash_function))
+        elsif use_long_lived_aws_credentials
+          @kafka = Kafka.new(
+            seed_brokers: @seed_brokers,
+            client_id: @client_id,
+            logger: logger,
+            connect_timeout: @connect_timeout,
+            socket_timeout: @socket_timeout,
+            ssl_ca_cert_file_path: @ssl_ca_cert,
+            ssl_client_cert: read_ssl_file(@ssl_client_cert),
+            ssl_client_cert_key: read_ssl_file(@ssl_client_cert_key),
+            ssl_client_cert_chain: read_ssl_file(@ssl_client_cert_chain),
+            ssl_ca_certs_from_system: @ssl_ca_certs_from_system,
+            sasl_over_ssl: @sasl_over_ssl,
+            ssl_verify_hostname: @ssl_verify_hostname,
+            resolve_seed_brokers: @resolve_seed_brokers,
+            sasl_aws_msk_iam_access_key_id: @sasl_aws_msk_iam_access_key_id,
+            sasl_aws_msk_iam_secret_key_id: @sasl_aws_msk_iam_secret_key_id,
+            sasl_aws_msk_iam_aws_region: @sasl_aws_msk_iam_aws_region,
+            partitioner: Kafka::Partitioner.new(hash_function: @partitioner_hash_function)
+          )
         else
           @kafka = Kafka.new(seed_brokers: @seed_brokers, client_id: @client_id, logger: logger, connect_timeout: @connect_timeout, socket_timeout: @socket_timeout, ssl_ca_cert_file_path: @ssl_ca_cert,
                              ssl_client_cert: read_ssl_file(@ssl_client_cert), ssl_client_cert_key: read_ssl_file(@ssl_client_cert_key), ssl_client_cert_chain: read_ssl_file(@ssl_client_cert_chain),