fluentd: Suppress unread configuration warning (#1242)

* suppress unread configuration warning

* make client certificate optional

fluentd/fluent-plugin-grafana-loki/fluent-plugin-grafana-loki.gemspec

@@ -4,7 +4,7 @@ $LOAD_PATH.push File.expand_path('lib', __dir__)
 
 Gem::Specification.new do |spec|
   spec.name    = 'fluent-plugin-grafana-loki'
-  spec.version = '1.2.1'
+  spec.version = '1.2.2'
   spec.authors = %w[woodsaj briangann]
   spec.email   = ['[email protected]', '[email protected]']
 

fluentd/fluent-plugin-grafana-loki/lib/fluent/plugin/out_loki.rb

@@ -76,7 +76,7 @@ def configure(conf)
         @record_accessors = {}
         conf.elements.select { |element| element.name == 'label' }.each do |element|
           element.each_pair do |k, v|
-            element.key?(k) # to suppress unread configuration warning
+            element.has_key?(k) # rubocop:disable Style/PreferredHashMethods #to suppress unread configuration warning
             v = k if v.empty?
             @record_accessors[k] = record_accessor_create(v)
           end
@@ -86,11 +86,13 @@ def configure(conf)
           @remove_keys_accessors.push(record_accessor_create(key))
         end
 
-        @cert = OpenSSL::X509::Certificate.new(File.read(@cert)) if @cert
-        @key = OpenSSL::PKey.read(File.read(key)) if @key
+        if !@key.nil? && !@cert.nil?
+          @cert = OpenSSL::X509::Certificate.new(File.read(@cert)) if @cert
+          @key = OpenSSL::PKey.read(File.read(@key)) if @key
 
-        if !@key.is_a?(OpenSSL::PKey::RSA) && !@key.is_a?(OpenSSL::PKey::DSA)
-          raise "Unsupported private key type #{key.class}"
+          if !@key.is_a?(OpenSSL::PKey::RSA) && !@key.is_a?(OpenSSL::PKey::DSA)
+            raise "Unsupported private key type #{key.class}"
+          end
         end
 
         if !@ca_cert.nil? && !File.exist?(@ca_cert)