Adding gems conditionally

Author: madebydna

Gemfile

@@ -3,5 +3,12 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in fluent-plugin-kafka.gemspec
 gemspec
 
-gem 'json', '2.7.3' # override of 2.7.4 version
-gem 'rdkafka', ENV['RDKAFKA_VERSION_MIN_RANGE'], ENV['RDKAFKA_VERSION_MAX_RANGE'] if ENV['USE_RDKAFKA']
+if ENV['USE_RDKAFKA']
+  gem 'rdkafka', ENV['RDKAFKA_VERSION_MIN_RANGE'], ENV['RDKAFKA_VERSION_MAX_RANGE']
+  min_version = Gem::Version.new('0.16.0')
+  min_range_version = Gem::Version.new(ENV['RDKAFKA_VERSION_MIN_RANGE'].split(' ').last)
+  if min_range_version >= min_version
+    gem 'aws-msk-iam-sasl-signer'
+    gem 'json', '2.7.3' # override of 2.7.4 version
+  end
+end

fluent-plugin-kafka.gemspec

@@ -19,8 +19,6 @@ Gem::Specification.new do |gem|
   gem.add_dependency "fluentd", [">= 0.10.58", "< 2"]
   gem.add_dependency 'ltsv'
   gem.add_dependency 'ruby-kafka', '>= 1.5.0', '< 2'
-  gem.add_dependency 'rdkafka'
-  gem.add_dependency 'aws-msk-iam-sasl-signer'
   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/out_rdkafka2.rb

@@ -4,7 +4,6 @@
 require 'fluent/plugin/kafka_plugin_util'
 
 require 'rdkafka'
-require 'aws_msk_iam_sasl_signer'
 
 begin
   rdkafka_version = Gem::Version::create(Rdkafka::VERSION)
@@ -16,6 +15,7 @@
     require_relative 'rdkafka_patch/0_14_0'
   elsif rdkafka_version >= Gem::Version.create('0.16.0')
     require_relative 'rdkafka_patch/0_16_0'
+    require 'aws_msk_iam_sasl_signer'
   end
 rescue LoadError, NameError
   raise "unable to patch rdkafka."
@@ -208,7 +208,6 @@ def add(level, message = nil)
           end
         end
       }
-      # HERE -----------------
       Rdkafka::Config.logger = log
       config = build_config
       @rdkafka = Rdkafka::Config.new(config)
@@ -217,7 +216,6 @@ def add(level, message = nil)
       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