fluent-cat: support secondary file

https://docs.fluentd.org/output/secondary_file#how-to-resend-secondary-file
explains that it supports secondary file to resend,
but it get error when [Fluent::EventTime, Hash] format is given.

  Input must be a map (got Array)

In this commit, check record content and support [Fluent::EventTime,
Hash] format too.

Note that fluent-cat ignore timestamp which is stored in secondary
records. (it is intended behavior for keeping consistency)

Signed-off-by: Kentaro Hayashi <[email protected]>

lib/fluent/command/cat.rb

@@ -152,14 +152,30 @@ def initialize(tag, connector, time_as_integer: false, retry_limit: 5)
     super()
   end
 
+  def secondary_record?(record)
+    record.class != Hash &&
+      record.size == 2 &&
+      record.first.class == Fluent::EventTime &&
+      record.last.class == Hash
+  end
+
   def write(record)
-    if record.class != Hash
-      raise ArgumentError, "Input must be a map (got #{record.class})"
+    unless secondary_record?(record)
+      if record.class != Hash
+        raise ArgumentError, "Input must be a map (got #{record.class})"
+      end
     end
 
     time = Fluent::EventTime.now
     time = time.to_i if @time_as_integer
-    entry = [time, record]
+    entry = if secondary_record?(record)
+              # Even though secondary contains Fluent::EventTime in record,
+              # fluent-cat just ignore it and set Fluent::EventTime.now instead.
+              # This specification is adopted to keep consistency.
+              [time, record.last]
+            else
+              [time, record]
+            end
     synchronize {
       unless write_impl([entry])
         # write failed

test/command/test_cat.rb

@@ -0,0 +1,96 @@
+require_relative '../helper'
+
+require 'test-unit'
+require 'open3'
+require 'fluent/plugin/output'
+require 'fluent/plugin/in_forward'
+require 'fluent/plugin/out_secondary_file'
+require 'fluent/test/driver/output'
+require 'fluent/test/driver/input'
+
+class TestFluentCat < ::Test::Unit::TestCase
+  def setup
+    Fluent::Test.setup
+    FileUtils.mkdir_p(TMP_DIR)
+    @record = { 'key' => 'value' }
+    @time = event_time
+    @es = Fluent::OneEventStream.new(@time, @record)
+    @primary = create_primary
+    metadata = @primary.buffer.new_metadata
+    @chunk = create_chunk(@primary, metadata, @es)
+  end
+
+  def teardown
+    FileUtils.rm_rf(TMP_DIR)
+  end
+
+  TMP_DIR = File.expand_path(File.dirname(__FILE__) + "/../tmp/command/fluent_cat#{ENV['TEST_ENV_NUMBER']}")
+  FLUENT_CAT_COMMAND = File.expand_path(File.dirname(__FILE__) + "/../../bin/fluent-cat")
+
+  PORT = unused_port
+  CONFIG = %[
+    port #{PORT}
+    bind 127.0.0.1
+  ]
+
+  SECONDARY_CONFIG = %[
+    directory #{TMP_DIR}
+  ]
+
+  class DummyOutput < Fluent::Plugin::Output
+    def write(chunk); end
+  end
+
+  def create_driver(conf=CONFIG)
+    Fluent::Test::Driver::Input.new(Fluent::Plugin::ForwardInput).configure(conf)
+  end
+
+  def create_primary(buffer_cofig = config_element('buffer'))
+    DummyOutput.new.configure(config_element('ROOT','',{}, [buffer_cofig]))
+  end
+
+  def create_secondary_driver(conf=SECONDARY_CONFIG)
+    c = Fluent::Test::Driver::Output.new(Fluent::Plugin::SecondaryFileOutput)
+    c.instance.acts_as_secondary(@primary)
+    c.configure(conf)
+  end
+
+  def create_chunk(primary, metadata, es)
+    primary.buffer.generate_chunk(metadata).tap do |c|
+      c.concat(es.to_msgpack_stream, es.size)
+      c.commit
+    end
+  end
+
+  sub_test_case "json" do
+    def test_cat_json
+      d = create_driver
+      d.run(expect_records: 1) do
+        Open3.pipeline_w("#{FLUENT_CAT_COMMAND} --port #{PORT} json") do |stdin|
+          stdin.puts('{"key":"value"}')
+          stdin.close
+        end
+      end
+      event = d.events.first
+      assert_equal([1, "json", @record],
+                   [d.events.size, event.first, event.last])
+    end
+  end
+
+  sub_test_case "msgpack" do
+    def test_cat_secondary_file
+      d = create_secondary_driver
+      path = d.instance.write(@chunk)
+      d = create_driver
+      d.run(expect_records: 1) do
+        Open3.pipeline_w("#{FLUENT_CAT_COMMAND} --port #{PORT} --format msgpack secondary") do |stdin|
+          stdin.write(File.read(path))
+          stdin.close
+        end
+      end
+      event = d.events.first
+      assert_equal([1, "secondary", @record],
+                   [d.events.size, event.first, event.last])
+    end
+  end
+end