Drop reevoocop and just use rubocop...

Make the syle more like the "comunity" guidelines to
make the codebase more accessable.

.rubocop.yml

@@ -0,0 +1,17 @@
+AllCops:
+  Exclude:
+    - '*.gemspec'
+
+Metrics/LineLength:
+  Max: 120
+  Exclude:
+    - 'test/**/*'
+Metrics/ClassLength:
+  Exclude:
+    - 'test/**/*'
+Metrics/AbcSize:
+  Exclude:
+    - 'test/**/*'
+Metrics/MethodLength:
+  Exclude:
+    - 'test/**/*'

Gemfile

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
-source "https://rubygems.org"
+
+source 'https://rubygems.org'
 
 gemspec

Rakefile

@@ -1,18 +1,19 @@
 # frozen_string_literal: true
-require "bundler/gem_tasks"
-require "rake/testtask"
-require "reevoocop/rake_task"
-require "fileutils"
 
-ReevooCop::RakeTask.new(:reevoocop)
+require 'bundler/gem_tasks'
+require 'rake/testtask'
+require 'rubocop/rake_task'
+require 'fileutils'
+
+RuboCop::RakeTask.new(:rubocop)
 
 Rake::TestTask.new(:test) do |t|
-  t.test_files = Dir["test/**/test_*.rb"]
+  t.test_files = Dir['test/**/test_*.rb']
 end
 
-task default: "docker:test"
-task build: "docker:test"
-task default: :reevoocop
+task default: 'docker:test'
+task build: 'docker:test'
+task default: :rubocop
 
 namespace :docker do
   distros = %i[ubuntu tdagent-ubuntu tdagent-centos]
@@ -22,10 +23,10 @@ namespace :docker do
     task distro do
       puts "testing on #{distro}"
       begin
-        FileUtils.cp("test/docker/Dockerfile.#{distro}", "Dockerfile")
-        sh "docker build ."
+        FileUtils.cp("test/docker/Dockerfile.#{distro}", 'Dockerfile')
+        sh 'docker build .'
       ensure
-        FileUtils.rm("Dockerfile")
+        FileUtils.rm('Dockerfile')
       end
     end
   end

fluent-plugin-systemd.gemspec

@@ -1,29 +1,28 @@
 # -*- encoding: utf-8 -*-
 # frozen_string_literal: true
 
-lib = File.expand_path("../lib", __FILE__)
+lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 
 Gem::Specification.new do |spec|
-  spec.name          = "fluent-plugin-systemd"
-  spec.version       = "0.3.1"
-  spec.authors       = ["Ed Robinson"]
-  spec.email         = ["[email protected]"]
+  spec.name          = 'fluent-plugin-systemd'
+  spec.version       = '0.3.1'
+  spec.authors       = ['Ed Robinson']
+  spec.email         = ['[email protected]']
 
-  spec.summary       = "Input plugin to read from systemd journal."
-  spec.description   = "This is a fluentd input plugin. It reads logs from the systemd journal."
-  spec.homepage      = "https://github.com/reevoo/fluent-plugin-systemd"
-  spec.license       = "MIT"
+  spec.summary       = 'Input plugin to read from systemd journal.'
+  spec.description   = 'This is a fluentd input plugin. It reads logs from the systemd journal.'
+  spec.homepage      = 'https://github.com/reevoo/fluent-plugin-systemd'
+  spec.license       = 'MIT'
 
+  spec.files         = Dir['lib/**/**.rb', 'README.md', 'LICENCE']
+  spec.require_paths = ['lib']
 
-  spec.files         = Dir["lib/**/**.rb", "README.md", "LICENCE"]
-  spec.require_paths = ["lib"]
+  spec.add_development_dependency 'bundler', '~> 1.10'
+  spec.add_development_dependency 'rake'
+  spec.add_development_dependency 'test-unit', '~> 2.5'
+  spec.add_development_dependency 'rubocop', '~> 0.53.0'
 
-  spec.add_development_dependency "bundler", "~> 1.10"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "test-unit", "~> 2.5"
-  spec.add_development_dependency "reevoocop"
-
-  spec.add_runtime_dependency "fluentd", [">= 0.14.11", "< 2"]
-  spec.add_runtime_dependency "systemd-journal", "~> 1.3"
+  spec.add_runtime_dependency 'fluentd', ['>= 0.14.11', '< 2']
+  spec.add_runtime_dependency 'systemd-journal', '~> 1.3'
 end

lib/fluent/plugin/filter_systemd_entry.rb

@@ -1,12 +1,13 @@
 # frozen_string_literal: true
-require "fluent/plugin/filter"
-require "fluent/plugin/systemd/entry_mutator"
+
+require 'fluent/plugin/filter'
+require 'fluent/plugin/systemd/entry_mutator'
 
 module Fluent
   module Plugin
     # Fluentd systemd/journal filter plugin
     class SystemdEntryFilter < Filter
-      Fluent::Plugin.register_filter("systemd_entry", self)
+      Fluent::Plugin.register_filter('systemd_entry', self)
 
       config_param :field_map, :hash, default: {}
       config_param :field_map_strict, :bool, default: false
@@ -16,9 +17,7 @@ class SystemdEntryFilter < Filter
       def configure(conf)
         super
         @mutator = SystemdEntryMutator.new(**@config_root_section.to_h)
-        if @mutator.field_map_strict && @mutator.field_map.empty?
-          log.warn("`field_map_strict` set to true with empty `field_map`, expect no fields")
-        end
+        @mutator.warnings.each { |warning| log.warn(warning) }
       end
 
       def filter(_tag, _time, entry)

lib/fluent/plugin/in_systemd.rb

@@ -1,33 +1,35 @@
 # frozen_string_literal: true
-require "systemd/journal"
-require "fluent/plugin/input"
-require "fluent/plugin/systemd/pos_writer"
-require "fluent/plugin/systemd/entry_mutator"
+
+require 'systemd/journal'
+require 'fluent/plugin/input'
+require 'fluent/plugin/systemd/pos_writer'
+require 'fluent/plugin/systemd/entry_mutator'
 
 module Fluent
   module Plugin
+    # Fluentd plugin for reading from the systemd journal
     class SystemdInput < Input # rubocop:disable Metrics/ClassLength
-      Fluent::Plugin.register_input("systemd", self)
+      Fluent::Plugin.register_input('systemd', self)
 
       helpers :timer, :storage
 
-      DEFAULT_STORAGE_TYPE = "local"
+      DEFAULT_STORAGE_TYPE = 'local'
 
-      config_param :path, :string, default: "/var/log/journal"
+      config_param :path, :string, default: '/var/log/journal'
       config_param :filters, :array, default: []
       config_param :pos_file, :string, default: nil, deprecated: "Use <storage> section with `persistent: true' instead"
       config_param :read_from_head, :bool, default: false
-      config_param :strip_underscores, :bool, default: false, deprecated: "Use <entry> section or `systemd_entry` " \
-                                                                          "filter plugin instead"
+      config_param :strip_underscores, :bool, default: false, deprecated: 'Use <entry> section or `systemd_entry` ' \
+                                                                          'filter plugin instead'
       config_param :tag, :string
 
       config_section :storage do
-        config_set_default :usage, "positions"
+        config_set_default :usage, 'positions'
         config_set_default :@type, DEFAULT_STORAGE_TYPE
         config_set_default :persistent, false
       end
 
-      config_section :entry, param_name: "entry_opts", required: false, multi: false do
+      config_section :entry, param_name: 'entry_opts', required: false, multi: false do
         config_param :field_map, :hash, default: {}
         config_param :field_map_strict, :bool, default: false
         config_param :fields_strip_underscores, :bool, default: false
@@ -37,14 +39,12 @@ class SystemdInput < Input # rubocop:disable Metrics/ClassLength
       def configure(conf)
         super
         @journal = nil
-        @pos_storage = PosWriter.new(@pos_file, storage_create(usage: "positions"))
+        @pos_storage = PosWriter.new(@pos_file, storage_create(usage: 'positions'))
         # legacy strip_underscores backwards compatibility (legacy takes
         # precedence and is mutually exclusive with the entry block)
         mut_opts = @strip_underscores ? { fields_strip_underscores: true } : @entry_opts.to_h
         @mutator = SystemdEntryMutator.new(**mut_opts)
-        if @mutator.field_map_strict && @mutator.field_map.empty?
-          log.warn("`field_map_strict` set to true with empty `field_map`, expect no fields")
-        end
+        @mutator.warnings.each { |warning| log.warn(warning) }
       end
 
       def start
@@ -81,7 +81,7 @@ def seek
       rescue Systemd::JournalError
         log.warn(
           "Could not seek to cursor #{cursor} found in pos file: #{@pos_storage.path}, " \
-          "falling back to reading from #{read_from}",
+          "falling back to reading from #{read_from}"
         )
         seek_to(read_from)
       end
@@ -120,7 +120,7 @@ def emit(entry)
         retries += 1
         sleep 1.5**retries + rand(0..3)
         retry
-      rescue => e
+      rescue => e # rubocop:disable Style/RescueStandardError
         log.error("Exception emitting record: #{e}")
       end
 

lib/fluent/plugin/systemd/entry_mutator.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
-require "fluent/config/error"
+
+require 'fluent/config/error'
 
 module Fluent
   module Plugin
@@ -19,12 +20,11 @@ module Plugin
     #   "<new_field2>" => ["<source_field2>"]
     # }
     class SystemdEntryMutator
-
       Options = Struct.new(
         :field_map,
         :field_map_strict,
         :fields_lowercase,
-        :fields_strip_underscores,
+        :fields_strip_underscores
       )
 
       def self.default_opts
@@ -56,6 +56,10 @@ def method_missing(sym, *args)
         super
       end
 
+      def respond_to_missing?(sym, include_private = false)
+        @opts.members.include?(sym) || super
+      end
+
       # The main run method that performs all configured mutations, if any,
       # against a single journal entry. Returns the mutated entry hash.
       # entry - hash or `Systemd::Journal:Entry`
@@ -91,16 +95,21 @@ def format_fields(entry, mapped = nil)
         end
       end
 
+      def warnings
+        return [] unless field_map_strict && field_map.empty?
+        '`field_map_strict` set to true with empty `field_map`, expect no fields'
+      end
+
       private
 
       def join_if_needed(values)
         values.compact!
         return values.first if values.length == 1
-        values.join(" ")
+        values.join(' ')
       end
 
       def format_field_name(name)
-        name = name.gsub(/\A_+/, "") if @opts.fields_strip_underscores
+        name = name.gsub(/\A_+/, '') if @opts.fields_strip_underscores
         name = name.downcase if @opts.fields_lowercase
         name
       end
@@ -116,8 +125,8 @@ def options_from_hash(opts)
       end
 
       def validate_options(opts)
-        validate_all_strings opts[:field_map].keys, "`field_map` keys must be strings"
-        validate_all_strings opts[:field_map].values, "`field_map` values must be strings or an array of strings", true
+        validate_all_strings opts[:field_map].keys, '`field_map` keys must be strings'
+        validate_all_strings opts[:field_map].values, '`field_map` values must be strings or an array of strings', true
         %i[field_map_strict fields_strip_underscores fields_lowercase].each do |opt|
           validate_boolean opts[opt], opt
         end
@@ -127,21 +136,21 @@ def validate_all_strings(arr, message, allow_nesting = false)
         valid = arr.all? do |value|
           value.is_a?(String) || allow_nesting && value.is_a?(Array) && value.all? { |key| key.is_a?(String) }
         end
-        fail Fluent::ConfigError, message unless valid
+        raise Fluent::ConfigError, message unless valid
       end
 
       def validate_boolean(value, name)
-        fail Fluent::ConfigError, "`#{name}` must be boolean" unless [true, false].include?(value)
+        raise Fluent::ConfigError, "`#{name}` must be boolean" unless [true, false].include?(value)
       end
 
-      # Compute the inverse of a human friendly field map `fm` which is what
+      # Compute the inverse of a human friendly field map `field_map` which is what
       # the mutator uses for the actual mapping. The resulting structure for
       # the inverse field map hash is:
       # {"<new_field_name>" => ["<source_field_name>", ...], ...}
-      def invert_field_map(fm)
+      def invert_field_map(field_map)
         invs = {}
-        fm.values.flatten.uniq.each do |cstm|
-          sysds = fm.select { |_, v| (v == cstm || v.include?(cstm)) }
+        field_map.values.flatten.uniq.each do |cstm|
+          sysds = field_map.select { |_, v| (v == cstm || v.include?(cstm)) }
           invs[cstm] = sysds.keys
         end
         invs

lib/fluent/plugin/systemd/pos_writer.rb

@@ -1,9 +1,19 @@
 # frozen_string_literal: true
-require "fluent/plugin/input"
+
+require 'fluent/plugin/input'
 
 module Fluent
   module Plugin
     class SystemdInput < Input
+      # This is used to write the systemd cursor to the configured storage
+      # We do this periodicly in a thread so as to not contend on resources
+      # that might be needed for more important tasks.
+      #
+      # When signaled to shutdown we ensure that the most recent cursor
+      # has been written.
+      #
+      # If fluentd stops runnning without cleanly shutting down PosWriter
+      # the cursor could be up to 1 second stale
       class PosWriter
         def initialize(pos_file, storage)
           @path = pos_file
@@ -76,7 +86,7 @@ def work
         def write_pos
           @lock.synchronize do
             if @written_cursor != @cursor
-              file = File.open(@path, "w+", 0o644)
+              file = File.open(@path, 'w+', 0o644)
               file.print @cursor
               file.close
               @written_cursor = @cursor

test/helper.rb

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
-require "test/unit"
-require "fluent/test"
-require "fluent/test/helpers"
+
+require 'test/unit'
+require 'fluent/test'
+require 'fluent/test/helpers'