Merge pull request #1176 from sonots/prevent_overwriting_reserved_pla…

…ceholders

Fix to prevent overwriting reserved placeholder keys such as tag

lib/fluent/plugin/filter_record_transformer.rb

@@ -204,7 +204,9 @@ def prepare_placeholders(placeholder_values)
             end
           elsif value.kind_of?(Hash) # record, etc
             value.each do |k, v|
-              placeholders.store("${#{k}}", v) # foo
+              unless placeholder_values.has_key?(k) # prevent overwriting reserved keys such as tag
+                placeholders.store("${#{k}}", v) # foo
+              end
               placeholders.store(%Q[${#{key}["#{k}"]}], v) # record["foo"]
             end
           else # string, interger, float, and others?

test/plugin/test_filter_record_transformer.rb

@@ -174,12 +174,11 @@ def filter(config, msgs = [''])
       d = create_driver(config)
       yield d if block_given?
       d.run {
-        msgs.each do |msg|
-          record = {
-            'eventType0' => 'bar',
-            'message'    => msg,
-          }
-          record = record.merge(msg) if msg.is_a?(Hash)
+        records = msgs.map do |msg|
+          next msg if msg.is_a?(Hash)
+          { 'eventType0' => 'bar', 'message' => msg }
+        end
+        records.each do |record|
           d.feed(@tag, @time, record)
         end
       }
@@ -273,6 +272,23 @@ def filter(config, msgs = [''])
         end
       end
 
+      test "Prevent overwriting reserved keys such as tag with enable_ruby #{enable_ruby}" do
+        config = %[
+          enable_ruby #{enable_ruby}
+          <record>
+            new_tag ${tag}
+            new_record_tag ${record["tag"]}
+          </record>
+        ]
+        records = [{'tag' => 'tag', 'time' => 'time'}]
+        filtered = filter(config, records)
+        filtered.each_with_index do |(_t, r), i|
+          assert_not_equal('tag', r['new_tag'])
+          assert_equal(@tag, r['new_tag'])
+          assert_equal('tag', r['new_record_tag'])
+        end
+      end
+
       test "hash values with placeholders with enable_ruby #{enable_ruby}" do
         config = %[
           enable_ruby #{enable_ruby}