Replacement operation is valid only on String and is in brackets.

mashhurs · mashhurs · commit c2934659c5ab · 2024-07-30T07:41:44.000-07:00
diff --git a/logstash-core/lib/logstash/util/substitution_variables.rb b/logstash-core/lib/logstash/util/substitution_variables.rb
@@ -74,9 +74,13 @@ def replace_placeholders(value)
         raise LogStash::ConfigurationError, "Cannot evaluate `#{placeholder}`. Replacement variable `#{name}` is not defined in a Logstash secret store " +
             "or as an Environment entry and there is no default value given."
       end
-      # if array string, remove literal brackets and make array
-      replacements = replacement.gsub(/[\[\]]/, '')
-      return replacements.split(', ').map(&:strip)
+      # if ENV carries array string, remove literal brackets and make array
+      if replacement.is_a?(String) && replacement.start_with?('[') && replacement.end_with?(']')
+        replacements = replacement.gsub(/[\[\]]/, '')
+        return replacements.split(', ').map(&:strip)
+      else
+        replacement.to_s
+      end
     end
   end # def replace_placeholders
 
