Use enum type on partial_metadata_format parameter

Signed-off-by: Hiroshi Hatake <[email protected]>

Author: cosmo0920

README.md

@@ -97,13 +97,15 @@ Use partial metadata to concatenate multiple records
 
 If true, keep partial metadata
 
-**partial\_metadata\_format** (string) (optional)
+**partial\_metadata\_format** (enum) (optional)
+
+Input format of the partial metadata (fluentd or journald docker log driver)
 
 Configure based on the input plugin, that is used.
 The docker fluentd and journald log drivers are behaving differently, so the plugin needs to know, what to look for.
 Use `docker-journald-lowercase`, if you have `fields_lowercase true` in the `journald` source config
 
-Valid options: `docker-fluentd`, `docker-journald`, `docker-journald-lowercase`
+Available values: `docker-fluentd`, `docker-journald`, `docker-journald-lowercase`
 
 Default value is `docker-fluentd`
 

lib/fluent/plugin/filter_concat.rb

@@ -35,7 +35,7 @@ class ConcatFilter < Filter
     desc "Use partial metadata to concatenate multiple records"
     config_param :use_partial_metadata, :bool, default: false
     desc "Input format of the partial metadata (fluentd or journald docker log driver)"
-    config_param :partial_metadata_format, :string, default: "docker-fluentd"
+    config_param :partial_metadata_format, :enum, list: [:"docker-fluentd", :"docker-journald", :"docker-journald-lowercase"], default: :"docker-fluentd"
     desc "If true, keep partial metadata"
     config_param :keep_partial_metadata, :bool, default: false
 
@@ -79,9 +79,6 @@ def configure(conf)
       if @use_partial_metadata && @partial_key
         raise Fluent::ConfigError, "use_partial_metadata and partial_key are exclusive"
       end
-      unless ["docker-fluentd", "docker-journald", "docker-journald-lowercase"].include?(@partial_metadata_format)
-        raise Fluent::ConfigError, "partial_metadata_format only supports docker-fluentd, docker-journald or docker-journald-lowercase"
-      end
 
       @mode = nil
       case
@@ -92,21 +89,21 @@ def configure(conf)
       when @use_partial_metadata
         @mode = :partial_metadata
         case @partial_metadata_format
-        when "docker-fluentd"
+        when :"docker-fluentd"
           @partial_message_field     = "partial_message".freeze
           @partial_id_field          = "partial_id".freeze
           @partial_ordinal_field     = "partial_ordinal".freeze
           @partial_last_field        = "partial_last".freeze
           @partial_message_indicator = @partial_message_field
-        when "docker-journald"
+        when :"docker-journald"
           @partial_message_field     = "CONTAINER_PARTIAL_MESSAGE".freeze
           @partial_id_field          = "CONTAINER_PARTIAL_ID".freeze
           @partial_ordinal_field     = "CONTAINER_PARTIAL_ORDINAL".freeze
           @partial_last_field        = "CONTAINER_PARTIAL_LAST".freeze
           # the journald log driver does not add CONTAINER_PARTIAL_MESSAGE to the last message
           # so we help ourself by using another indicator
           @partial_message_indicator = @partial_id_field
-        when "docker-journald-lowercase"
+        when :"docker-journald-lowercase"
           @partial_message_field     = "container_partial_message".freeze
           @partial_id_field          = "container_partial_id".freeze
           @partial_ordinal_field     = "container_partial_ordinal".freeze