Rename filters to matches

I felt the term filters was being somewhat overloaded since fluentd
also has a concept of filters.

In the journalctl documentation these expressions are refered to
as matches... so it seems resonable to do the same...

The filters param will continue to work, with a warning...

Author: errm

lib/fluent/plugin/in_systemd.rb

@@ -15,7 +15,8 @@ class SystemdInput < Input
       DEFAULT_STORAGE_TYPE = 'local'
 
       config_param :path, :string, default: '/var/log/journal'
-      config_param :filters, :array, default: []
+      config_param :filters, :array, default: [], deprecated: 'filters has been renamed as matches'
+      config_param :matches, :array, default: nil
       config_param :read_from_head, :bool, default: false
       config_param :tag, :string
 
@@ -54,7 +55,7 @@ def init_journal
         # make sure initial call to wait doesn't return :invalidate
         # see https://github.com/ledbettj/systemd-journal/issues/70
         @journal.wait(0)
-        @journal.filter(*@filters)
+        @journal.filter(*(@matches || @filters))
         seek
         true
       rescue Systemd::JournalError => e

test/plugin/test_in_systemd.rb

@@ -83,6 +83,10 @@ def setup
       filters [{ "_SYSTEMD_UNIT": "systemd-journald.service" }]
     )
 
+    @matches_config = @head_config + %(
+      matches [{ "_SYSTEMD_UNIT": "systemd-journald.service" }]
+    )
+
     @tail_config = @storage_config + %(
       read_from_head false
     )
@@ -94,7 +98,7 @@ def setup
   end
 
   attr_reader :journal, :base_config, :head_config,
-              :filter_config, :tail_config, :not_present_config,
+              :matches_config, :filter_config, :tail_config, :not_present_config,
               :badmsg_config, :storage_path, :storage_config
 
   def create_driver(config)
@@ -180,6 +184,7 @@ def test_backoff_on_buffer_error
     d.run(expect_emits: 1)
   end
 
+  # deprecated and replaced with matches
   def test_reading_with_filters
     d = create_driver(filter_config)
     d.end_if do
@@ -189,6 +194,15 @@ def test_reading_with_filters
     assert_equal 3, d.events.size
   end
 
+  def test_reading_with_matches
+    d = create_driver(matches_config)
+    d.end_if do
+      d.events.size >= 3
+    end
+    d.run(timeout: 5)
+    assert_equal 3, d.events.size
+  end
+
   def test_reading_from_a_pos
     write_pos 's=add4782f78ca4b6e84aa88d34e5b4a9d;i=13f;b=4737ffc504774b3ba67020bc947f1bc0;m=ffadd;t=4d905e49a6291;x=9a11dd9ffee96e9f'
     d = create_driver(head_config)