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Testing Forward Output Plugin Implementation in Fluent/Fluentd

This test suite validates the functionality of Fluentd’s forward output plugin, testing data forwarding, network connectivity, and protocol handling between Fluentd nodes. The tests cover core functionality including buffering, acknowledgment handling, security features, and connection management.

Test Coverage Overview

The test suite provides comprehensive coverage of the forward output plugin’s capabilities.

Key areas tested include:
  • Basic data forwarding and event handling
  • Buffer management and chunk transmission
  • ACK/response handling between nodes
  • Security features including shared key authentication
  • Connection management including keepalive and reconnection
  • TLS/SSL transport encryption

Implementation Analysis

The testing approach uses minitest framework with extensive mocking and stubbing to validate network interactions.

Key testing patterns include:
  • Driver-based testing with input/output plugin pairs
  • Network socket mocking for connection validation
  • Time-based testing for timeout scenarios
  • Configuration validation across multiple modes

Technical Details

Testing tools and configuration:
  • Minitest test framework
  • Fluent test drivers for input/output simulation
  • Socket mocking with flexmock
  • Test configuration management
  • Buffer chunk simulation
  • Network timeout handling

Best Practices Demonstrated

The test suite demonstrates several testing best practices:

  • Comprehensive edge case coverage
  • Proper test isolation and cleanup
  • Systematic configuration testing
  • Network failure scenario handling
  • Security testing patterns
  • Connection lifecycle management

fluent/fluentd

test/plugin/test_out_forward.rb

            
require_relative '../helper'
require 'fluent/test/driver/output'
require 'fluent/plugin/out_forward'
require 'flexmock/test_unit'

require 'fluent/test/driver/input'
require 'fluent/plugin/in_forward'

class ForwardOutputTest < Test::Unit::TestCase
  def setup
    Fluent::Test.setup
    FileUtils.rm_rf(TMP_DIR)
    FileUtils.mkdir_p(TMP_DIR)
    @d = nil
    # forward plugin uses TCP and UDP sockets on the same port number
    @target_port = unused_port(protocol: :all)
  end

  def teardown
    @d.instance_shutdown if @d
    @port = nil
  end

  TMP_DIR = File.join(__dir__, "../tmp/out_forward#{ENV['TEST_ENV_NUMBER']}")

  TARGET_HOST = '127.0.0.1'

  def config
    %[
      send_timeout 51
      heartbeat_type udp
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
    ]
  end

  def target_config
    %[
      port #{@target_port}
      bind #{TARGET_HOST}
    ]
  end

  def create_driver(conf=config)
    Fluent::Test::Driver::Output.new(Fluent::Plugin::ForwardOutput) {
      attr_reader :sent_chunk_ids, :ack_handler, :discovery_manager

      def initialize
        super
        @sent_chunk_ids = []
      end

      def try_write(chunk)
        retval = super
        @sent_chunk_ids << chunk.unique_id
        retval
      end
    }.configure(conf)
  end

  test 'configure' do
    @d = d = create_driver(%[
      self_hostname localhost
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
    ])
    nodes = d.instance.nodes
    assert_equal 60, d.instance.send_timeout
    assert_equal :transport, d.instance.heartbeat_type
    assert_equal 1, nodes.length
    assert_nil d.instance.connect_timeout
    node = nodes.first
    assert_equal "test", node.name
    assert_equal '127.0.0.1', node.host
    assert_equal @target_port, node.port
  end

  test 'configure_traditional' do
    @d = d = create_driver(<<EOL)
      self_hostname localhost
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
      buffer_chunk_limit 10m
EOL
    instance = d.instance
    assert instance.chunk_key_tag
    assert !instance.chunk_key_time
    assert_equal [], instance.chunk_keys
    assert{ instance.buffer.is_a?(Fluent::Plugin::MemoryBuffer) }
    assert_equal( 10*1024*1024, instance.buffer.chunk_limit_size )
  end

  test 'configure timeouts' do
    @d = d = create_driver(%[
      send_timeout 30
      connect_timeout 10
      hard_timeout 15
      ack_response_timeout 20
      <server>
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
    ])
    assert_equal 30, d.instance.send_timeout
    assert_equal 10, d.instance.connect_timeout
    assert_equal 15, d.instance.hard_timeout
    assert_equal 20, d.instance.ack_response_timeout
  end

  test 'configure_udp_heartbeat' do
    @d = d = create_driver(config + "\nheartbeat_type udp")
    assert_equal :udp, d.instance.heartbeat_type
  end

  test 'configure_none_heartbeat' do
    @d = d = create_driver(config + "\nheartbeat_type none")
    assert_equal :none, d.instance.heartbeat_type
  end

  test 'configure_expire_dns_cache' do
    @d = d = create_driver(config + "\nexpire_dns_cache 5")
    assert_equal 5, d.instance.expire_dns_cache
  end

  test 'configure_dns_round_robin udp' do
    assert_raise(Fluent::ConfigError) do
      create_driver(config + "\nheartbeat_type udp\ndns_round_robin true")
    end
  end

  test 'configure_dns_round_robin transport' do
    @d = d = create_driver(config + "\nheartbeat_type transport\ndns_round_robin true")
    assert_equal true, d.instance.dns_round_robin
  end

  test 'configure_dns_round_robin none' do
    @d = d = create_driver(config + "\nheartbeat_type none\ndns_round_robin true")
    assert_equal true, d.instance.dns_round_robin
  end

  test 'configure_no_server' do
    assert_raise(Fluent::ConfigError, 'forward output plugin requires at least one <server> is required') do
      create_driver('')
    end
  end

  test 'configure with ignore_network_errors_at_startup' do
    normal_conf = config_element('match', '**', {}, [
        config_element('server', '', {'name' => 'test', 'host' => 'unexisting.yaaaaaaaaaaaaaay.host.example.com'})
      ])

    if Socket.const_defined?(:ResolutionError) # as of Ruby 3.3
      error_class = Socket::ResolutionError
    else
      error_class = SocketError
    end

    assert_raise error_class do
      create_driver(normal_conf)
    end

    conf = config_element('match', '**', {'ignore_network_errors_at_startup' => 'true'}, [
        config_element('server', '', {'name' => 'test', 'host' => 'unexisting.yaaaaaaaaaaaaaay.host.example.com'})
      ])
    @d = d = create_driver(conf)
    expected_log = "failed to resolve node name when configured"
    expected_detail = "server=\"test\" error_class=#{error_class.name}"
    logs = d.logs
    assert{ logs.any?{|log| log.include?(expected_log) && log.include?(expected_detail) } }
  end

  data('CA cert'     => 'tls_ca_cert_path',
       'non CA cert' => 'tls_cert_path')
  test 'configure tls_cert_path/tls_ca_cert_path' do |param|
    dummy_cert_path = File.join(TMP_DIR, "dummy_cert.pem")
    FileUtils.touch(dummy_cert_path)
    conf = %[
      send_timeout 5
      transport tls
      tls_insecure_mode true
      #{param} #{dummy_cert_path}
      <server>
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
    ]

    @d = d = create_driver(conf)
    # In the plugin, tls_ca_cert_path is used for both cases
    assert_equal([dummy_cert_path], d.instance.tls_ca_cert_path)
  end

  sub_test_case "certstore loading parameters for Windows" do
    test 'certstore related config parameters' do
      omit "certstore related values raise error on not Windows" if Fluent.windows?
      conf = %[
        send_timeout 5
        transport tls
        tls_cert_logical_store_name Root
        tls_cert_thumbprint a909502dd82ae41433e6f83886b00d4277a32a7b
        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]

      assert_raise(Fluent::ConfigError) do
        create_driver(conf)
      end
    end

    test 'cert_logical_store_name and tls_cert_thumbprint default values' do
      conf = %[
        send_timeout 5
        transport tls
        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]

      @d = d = create_driver(conf)
      assert_nil d.instance.tls_cert_logical_store_name
      assert_nil d.instance.tls_cert_thumbprint
    end

    data('CA cert'     => 'tls_ca_cert_path',
         'non CA cert' => 'tls_cert_path')
    test 'specify tls_cert_logical_store_name and tls_cert_path should raise error' do |param|
      omit "Loading CertStore feature works only Windows" unless Fluent.windows?
      dummy_cert_path = File.join(TMP_DIR, "dummy_cert.pem")
      FileUtils.touch(dummy_cert_path)
      conf = %[
        send_timeout 5
        transport tls
        #{param} #{dummy_cert_path}
        tls_cert_logical_store_name Root
        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]

      assert_raise(Fluent::ConfigError) do
        create_driver(conf)
      end
    end

    test 'configure cert_logical_store_name and tls_cert_thumbprint' do
      omit "Loading CertStore feature works only Windows" unless Fluent.windows?
      conf = %[
        send_timeout 5
        transport tls
        tls_cert_logical_store_name Root
        tls_cert_thumbprint a909502dd82ae41433e6f83886b00d4277a32a7b
        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]

      @d = d = create_driver(conf)
      assert_equal "Root", d.instance.tls_cert_logical_store_name
      assert_equal "a909502dd82ae41433e6f83886b00d4277a32a7b", d.instance.tls_cert_thumbprint
    end
  end

  test 'server is an abbreviation of static type of service_discovery' do
    @d = d = create_driver(%[
<server>
  host 127.0.0.1
  port 1234
</server>

<service_discovery>
  @type static

  <service>
    host 127.0.0.1
    port 1235
  </service>
</service_discovery>
    ])


    assert_equal(
      [
        { host: '127.0.0.1', port: 1234 },
        { host: '127.0.0.1', port: 1235 },
      ],
      d.instance.discovery_manager.services.collect do |service|
        { host: service.host, port: service.port }
      end
    )
  end

  test 'pass username and password as empty string to HandshakeProtocol' do
    config_path = File.join(TMP_DIR, "sd_file.conf")
    File.open(config_path, 'w') do |file|
      file.write(%[
- 'host': 127.0.0.1
  'port': 1234
  'weight': 1
])
    end

    mock(Fluent::Plugin::ForwardOutput::HandshakeProtocol).new(log: anything, hostname: nil, shared_key: anything, password: '', username: '')
    @d = d = create_driver(%[
<service_discovery>
  @type file
  path #{config_path}
</service_discovery>
    ])

    assert_equal 1, d.instance.discovery_manager.services.size
    assert_equal '127.0.0.1', d.instance.discovery_manager.services[0].host
    assert_equal 1234, d.instance.discovery_manager.services[0].port
  end

  test 'compress_default_value' do
    @d = d = create_driver
    assert_equal :text, d.instance.compress

    node = d.instance.nodes.first
    assert_equal :text, node.instance_variable_get(:@compress)
  end

  test 'set_compress_is_gzip' do
    @d = d = create_driver(config + %[compress gzip])
    assert_equal :gzip, d.instance.compress
    assert_equal :gzip, d.instance.buffer.compress

    node = d.instance.nodes.first
    assert_equal :gzip, node.instance_variable_get(:@compress)
  end

  test 'set_compress_is_gzip_in_buffer_section' do
    mock = flexmock($log)
    mock.should_receive(:log).with("buffer is compressed.  If you also want to save the bandwidth of a network, Add `compress` configuration in <match>")

    @d = d = create_driver(config + %[
       <buffer>
         type memory
         compress gzip
       </buffer>
     ])
    assert_equal :text, d.instance.compress
    assert_equal :gzip, d.instance.buffer.compress

    node = d.instance.nodes.first
    assert_equal :text, node.instance_variable_get(:@compress)
  end

  test 'phi_failure_detector disabled' do
    @d = d = create_driver(config + %[phi_failure_detector false \n phi_threshold 0])
    node = d.instance.nodes.first
    stub(node.failure).phi { raise 'Should not be called' }
    node.tick
    assert_true node.available?
  end

  test 'phi_failure_detector enabled' do
    @d = d = create_driver(config + %[phi_failure_detector true \n phi_threshold 0])
    node = d.instance.nodes.first
    node.tick
    assert_false node.available?
  end

  test 'require_ack_response is disabled in default' do
    @d = d = create_driver(config)
    assert_equal false, d.instance.require_ack_response
    assert_equal 190, d.instance.ack_response_timeout
  end

  test 'require_ack_response can be enabled' do
    @d = d = create_driver(config + %[
      require_ack_response true
      ack_response_timeout 2s
    ])
    d.instance_start
    assert d.instance.require_ack_response
    assert_equal 2, d.instance.ack_response_timeout
  end

  test 'suspend_flush is disable before before_shutdown' do
    @d = d = create_driver(config + %[
      require_ack_response true
      ack_response_timeout 2s
    ])
    d.instance_start
    assert_false d.instance.instance_variable_get(:@suspend_flush)
  end

  test 'suspend_flush should be enabled and try_flush returns nil after before_shutdown' do
    @d = d = create_driver(config + %[
      require_ack_response true
      ack_response_timeout 2s
    ])
    d.instance_start
    d.instance.before_shutdown
    assert_true d.instance.instance_variable_get(:@suspend_flush)
    assert_nil d.instance.try_flush
  end

  test 'verify_connection_at_startup is disabled in default' do
    @d = d = create_driver(config)
    assert_false d.instance.verify_connection_at_startup
  end

  test 'verify_connection_at_startup can be enabled' do
    @d = d = create_driver(config + %[
      verify_connection_at_startup true
    ])
    assert_true d.instance.verify_connection_at_startup
  end

  test 'send tags in str (utf-8 strings)' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[flush_interval 1s])

    time = event_time("2011-01-02 13:14:15 UTC")

    tag_in_utf8 = "test.utf8".encode("utf-8")
    tag_in_ascii = "test.ascii".encode("ascii-8bit")

    emit_events = [
      [tag_in_utf8, time, {"a" => 1}],
      [tag_in_ascii, time, {"a" => 2}],
    ]

    stub(d.instance.ack_handler).read_ack_from_sock(anything).never
    assert_rr do
      target_input_driver.run(expect_records: 2) do
        d.run do
          emit_events.each do |tag, t, record|
            d.feed(tag, t, record)
          end
        end
      end
    end

    events = target_input_driver.events
    assert_equal_event_time(time, events[0][1])
    assert_equal ['test.utf8', time, emit_events[0][2]], events[0]
    assert_equal Encoding::UTF_8, events[0][0].encoding
    assert_equal_event_time(time, events[1][1])
    assert_equal ['test.ascii', time, emit_events[1][2]], events[1]
    assert_equal Encoding::UTF_8, events[1][0].encoding
  end

  test 'send_with_time_as_integer' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[flush_interval 1s])

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]

    stub(d.instance.ack_handler).read_ack_from_sock(anything).never
    assert_rr do
      target_input_driver.run(expect_records: 2) do
        d.run(default_tag: 'test') do
          records.each do |record|
            d.feed(time, record)
          end
        end
      end
    end

    events = target_input_driver.events
    assert_equal_event_time(time, events[0][1])
    assert_equal ['test', time, records[0]], events[0]
    assert_equal_event_time(time, events[1][1])
    assert_equal ['test', time, records[1]], events[1]
  end

  test 'send_without_time_as_integer' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[
      flush_interval 1s
      time_as_integer false
    ])

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    stub(d.instance.ack_handler).read_ack_from_sock(anything).never
    assert_rr do
      target_input_driver.run(expect_records: 2) do
        d.run(default_tag: 'test') do
          records.each do |record|
            d.feed(time, record)
          end
        end
      end
    end

    events = target_input_driver.events
    assert_equal_event_time(time, events[0][1])
    assert_equal ['test', time, records[0]], events[0]
    assert_equal_event_time(time, events[1][1])
    assert_equal ['test', time, records[1]], events[1]
  end

  test 'send_comprssed_message_pack_stream_if_compress_is_gzip' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[
      flush_interval 1s
      compress gzip
    ])

    time = event_time('2011-01-02 13:14:15 UTC')

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    target_input_driver.run(expect_records: 2) do
      d.run(default_tag: 'test') do
        records.each do |record|
          d.feed(time, record)
        end
      end
    end

    event_streams = target_input_driver.event_streams
    assert_true event_streams[0][1].is_a?(Fluent::CompressedMessagePackEventStream)

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]
  end

  test 'send_to_a_node_supporting_responses' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[flush_interval 1s])

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    # not attempt to receive responses
    stub(d.instance.ack_handler).read_ack_from_sock(anything).never
    assert_rr do
      target_input_driver.run(expect_records: 2) do
        d.run(default_tag: 'test') do
          records.each do |record|
            d.feed(time, record)
          end
        end
      end
    end

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]
  end

  test 'send_to_a_node_not_supporting_responses' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[flush_interval 1s])

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    # not attempt to receive responses
    stub(d.instance.ack_handler).read_ack_from_sock(anything).never
    assert_rr do
      target_input_driver.run(expect_records: 2) do
        d.run(default_tag: 'test') do
          records.each do |record|
            d.feed(time, record)
          end
        end
      end
    end

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]
  end

  test 'a node supporting responses' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[
      require_ack_response true
      <buffer tag>
        flush_mode immediate
        retry_type periodic
        retry_wait 30s
        flush_at_shutdown true
      </buffer>
    ])

    time = event_time("2011-01-02 13:14:15 UTC")

    acked_chunk_ids = []
    nacked = false
    mock.proxy(d.instance.ack_handler).read_ack_from_sock(anything) do |info, success|
      if success
        acked_chunk_ids << info.chunk_id
      else
        nacked = true
      end
      [info, success]
    end

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    target_input_driver.run(expect_records: 2, timeout: 5) do
      d.end_if { acked_chunk_ids.size > 0 || nacked }
      d.run(default_tag: 'test', wait_flush_completion: false, shutdown: false) do
        d.feed([[time, records[0]], [time,records[1]]])
      end
    end

    assert(!nacked, d.instance.log.logs.join)

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]

    assert_equal 1, acked_chunk_ids.size
    assert_equal d.instance.sent_chunk_ids.first, acked_chunk_ids.first
  end

  test 'a node supporting responses after stop' do
    target_input_driver = create_target_input_driver

    @d = d = create_driver(config + %[
      require_ack_response true
      <buffer tag>
        flush_mode immediate
        retry_type periodic
        retry_wait 30s
        flush_at_shutdown true
      </buffer>
    ])

    time = event_time("2011-01-02 13:14:15 UTC")

    acked_chunk_ids = []
    nacked = false
    mock.proxy(d.instance.ack_handler).read_ack_from_sock(anything) do |info, success|
      if success
        acked_chunk_ids << info.chunk_id
      else
        nacked = true
      end
      [info, success]
    end

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    target_input_driver.run(expect_records: 2, timeout: 5) do
      d.end_if { acked_chunk_ids.size > 0 || nacked }
      d.run(default_tag: 'test', wait_flush_completion: false, shutdown: false) do
        d.instance.stop
        d.feed([[time, records[0]], [time,records[1]]])
        d.instance.before_shutdown
        d.instance.shutdown
        d.instance.after_shutdown
      end
    end

    assert(!nacked, d.instance.log.logs.join)

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]

    assert_equal 1, acked_chunk_ids.size
    assert_equal d.instance.sent_chunk_ids.first, acked_chunk_ids.first
  end

  data('ack true' => true,
       'ack false' => false)
  test 'TLS transport and ack parameter combination' do |ack|
    omit "TLS and 'ack false' always fails on AppVeyor. Need to debug" if Fluent.windows? && !ack

    input_conf = target_config + %[
                   <transport tls>
                     insecure true
                   </transport>
                 ]
    target_input_driver = create_target_input_driver(conf: input_conf)

    output_conf = %[
      send_timeout 5
      require_ack_response #{ack}
      transport tls
      tls_insecure_mode true
      <server>
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
      <buffer>
        #flush_mode immediate
        flush_interval 0s
        flush_at_shutdown false # suppress errors in d.instance_shutdown
      </buffer>
    ]
    @d = d = create_driver(output_conf)

    time = event_time("2011-01-02 13:14:15 UTC")
    records = [{"a" => 1}, {"a" => 2}]
    target_input_driver.run(expect_records: 2, timeout: 3) do
      d.run(default_tag: 'test', wait_flush_completion: false, shutdown: false) do
        records.each do |record|
          d.feed(time, record)
        end
      end
    end

    events = target_input_driver.events
    assert{ events != [] }
    assert_equal(['test', time, records[0]], events[0])
    assert_equal(['test', time, records[1]], events[1])
  end

  test 'a destination node not supporting responses by just ignoring' do
    target_input_driver = create_target_input_driver(response_stub: ->(_option) { nil }, disconnect: false)

    @d = d = create_driver(config + %[
      require_ack_response true
      ack_response_timeout 1s
      <buffer tag>
        flush_mode immediate
        retry_type periodic
        retry_wait 30s
        flush_at_shutdown false # suppress errors in d.instance_shutdown
        flush_thread_interval 30s
      </buffer>
    ])

    node = d.instance.nodes.first
    delayed_commit_timeout_value = nil

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    target_input_driver.end_if{ d.instance.rollback_count > 0 }
    target_input_driver.end_if{ !node.available? }
    target_input_driver.run(expect_records: 2, timeout: 25) do
      d.run(default_tag: 'test', timeout: 20, wait_flush_completion: false, shutdown: false, flush: false) do
        delayed_commit_timeout_value = d.instance.delayed_commit_timeout
        d.feed([[time, records[0]], [time,records[1]]])
      end
    end

    assert_equal (1 + 2), delayed_commit_timeout_value

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]

    assert{ d.instance.rollback_count > 0 }

    logs = d.instance.log.logs
    assert{ logs.any?{|log| log.include?("no response from node. regard it as unavailable.") } }
  end

  test 'a destination node not supporting responses by disconnection' do
    target_input_driver = create_target_input_driver(response_stub: ->(_option) { nil }, disconnect: true)

    @d = d = create_driver(config + %[
      require_ack_response true
      ack_response_timeout 1s
      <buffer tag>
        flush_mode immediate
        retry_type periodic
        retry_wait 30s
        flush_at_shutdown false # suppress errors in d.instance_shutdown
        flush_thread_interval 30s
      </buffer>
    ])

    node = d.instance.nodes.first
    delayed_commit_timeout_value = nil

    time = event_time("2011-01-02 13:14:15 UTC")

    records = [
      {"a" => 1},
      {"a" => 2}
    ]
    target_input_driver.end_if{ d.instance.rollback_count > 0 }
    target_input_driver.end_if{ !node.available? }
    target_input_driver.run(expect_records: 2, timeout: 25) do
      d.run(default_tag: 'test', timeout: 20, wait_flush_completion: false, shutdown: false, flush: false) do
        delayed_commit_timeout_value = d.instance.delayed_commit_timeout
        d.feed([[time, records[0]], [time,records[1]]])
      end
    end

    assert_equal (1 + 2), delayed_commit_timeout_value

    events = target_input_driver.events
    assert_equal ['test', time, records[0]], events[0]
    assert_equal ['test', time, records[1]], events[1]

    assert{ d.instance.rollback_count > 0 }

    logs = d.instance.log.logs
    assert{ logs.any?{|log| log.include?("no response from node. regard it as unavailable.") } }
  end

  test 'authentication_with_shared_key' do
    input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                     <client>
                       host 127.0.0.1
                     </client>
                   </security>
                 ]
    target_input_driver = create_target_input_driver(conf: input_conf)

    output_conf = %[
      send_timeout 51
      <security>
        self_hostname localhost
        shared_key fluentd-sharedkey
      </security>
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
        shared_key fluentd-sharedkey
      </server>
    ]
    @d = d = create_driver(output_conf)

    time = event_time("2011-01-02 13:14:15 UTC")
    records = [
      {"a" => 1},
      {"a" => 2}
    ]

    target_input_driver.run(expect_records: 2, timeout: 15) do
      d.run(default_tag: 'test') do
        records.each do |record|
          d.feed(time, record)
        end
      end
    end

    events = target_input_driver.events
    assert{ events != [] }
    assert_equal(['test', time, records[0]], events[0])
    assert_equal(['test', time, records[1]], events[1])
  end

  test 'keepalive + shared_key' do
    input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                   </security>
                 ]
    target_input_driver = create_target_input_driver(conf: input_conf)

    output_conf = %[
      send_timeout 51
      keepalive true
      <security>
        self_hostname localhost
        shared_key fluentd-sharedkey
      </security>
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
      </server>
    ]
    @d = d = create_driver(output_conf)

    time = event_time('2011-01-02 13:14:15 UTC')
    records = [{ 'a' => 1 }, { 'a' => 2 }]
    records2 = [{ 'b' => 1}, { 'b' => 2}]
    target_input_driver.run(expect_records: 4, timeout: 15) do
      d.run(default_tag: 'test') do
        records.each do |record|
          d.feed(time, record)
        end

        d.flush # emit buffer to reuse same socket later
        records2.each do |record|
          d.feed(time, record)
        end
      end
    end

    events = target_input_driver.events
    assert{ events != [] }
    assert_equal(['test', time, records[0]], events[0])
    assert_equal(['test', time, records[1]], events[1])
    assert_equal(['test', time, records2[0]], events[2])
    assert_equal(['test', time, records2[1]], events[3])
  end

   test 'authentication_with_user_auth' do
    input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                     user_auth true
                     <user>
                       username fluentd
                       password fluentd
                     </user>
                     <client>
                       host 127.0.0.1
                     </client>
                   </security>
                 ]
    target_input_driver = create_target_input_driver(conf: input_conf)

    output_conf = %[
      send_timeout 51
      <security>
        self_hostname localhost
        shared_key fluentd-sharedkey
      </security>
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
        shared_key fluentd-sharedkey
        username fluentd
        password fluentd
      </server>
    ]
    @d = d = create_driver(output_conf)

    time = event_time("2011-01-02 13:14:15 UTC")
    records = [
      {"a" => 1},
      {"a" => 2}
    ]

    target_input_driver.run(expect_records: 2, timeout: 15) do
      d.run(default_tag: 'test') do
        records.each do |record|
          d.feed(time, record)
        end
      end
    end

    events = target_input_driver.events
    assert{ events != [] }
    assert_equal(['test', time, records[0]], events[0])
    assert_equal(['test', time, records[1]], events[1])
  end

  # This test is not 100% but test failed with previous Node implementation which has race condition
  test 'Node with security is thread-safe on multi threads' do
    input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                     <client>
                       host 127.0.0.1
                     </client>
                   </security>
                 ]
    target_input_driver = create_target_input_driver(conf: input_conf)
    output_conf = %[
      send_timeout 51
      <security>
        self_hostname localhost
        shared_key fluentd-sharedkey
      </security>
      <server>
        name test
        host #{TARGET_HOST}
        port #{@target_port}
        shared_key fluentd-sharedkey
      </server>
    ]
    @d = d = create_driver(output_conf)

    chunk = Fluent::Plugin::Buffer::MemoryChunk.new(Fluent::Plugin::Buffer::Metadata.new(nil, nil, nil))
    target_input_driver.run(timeout: 15) do
      d.run(shutdown: false) do
        node = d.instance.nodes.first
        arr = []
        4.times {
          arr << Thread.new {
            node.send_data('test', chunk) rescue nil
          }
        }
        arr.each { |a| a.join }
      end
    end

    logs = d.logs
    assert_false(logs.any? { |log|
                   log.include?("invalid format for PONG message") || log.include?("shared key mismatch")
                 }, "Actual log:\n#{logs.join}")
  end

  def create_target_input_driver(response_stub: nil, disconnect: false, conf: target_config)
    require 'fluent/plugin/in_forward'

    # TODO: Support actual TCP heartbeat test
    Fluent::Test::Driver::Input.new(Fluent::Plugin::ForwardInput) {
      if response_stub.nil?
        # do nothing because in_forward responds for ack option in default
      else
        define_method(:response) do |options|
          return response_stub.(options)
        end
      end
    }.configure(conf)
  end

  test 'heartbeat_type_none' do
    @d = d = create_driver(config + "\nheartbeat_type none")
    node = d.instance.nodes.first
    assert_equal Fluent::Plugin::ForwardOutput::NoneHeartbeatNode, node.class

    d.instance_start
    assert_nil d.instance.instance_variable_get(:@loop)   # no HeartbeatHandler, or HeartbeatRequestTimer
    assert_nil d.instance.instance_variable_get(:@thread) # no HeartbeatHandler, or HeartbeatRequestTimer

    stub(node.failure).phi { raise 'Should not be called' }
    node.tick
    assert_true node.available?
  end

  test 'heartbeat_type_udp' do
    @d = d = create_driver(config + "\nheartbeat_type udp")

    d.instance_start
    usock = d.instance.instance_variable_get(:@usock)
    servers = d.instance.instance_variable_get(:@_servers)
    timers = d.instance.instance_variable_get(:@_timers)
    assert_equal Fluent::PluginHelper::Socket::WrappedSocket::UDP, usock.class
    assert_kind_of UDPSocket, usock
    assert servers.find{|s| s.title == :out_forward_heartbeat_receiver }
    assert timers.include?(:out_forward_heartbeat_request)

    mock(usock).send("\0", 0, Socket.pack_sockaddr_in(@target_port, '127.0.0.1')).once
    d.instance.send(:on_heartbeat_timer)
  end

  test 'acts_as_secondary' do
    i = Fluent::Plugin::ForwardOutput.new
    conf = config_element(
      'match',
      'primary.**',
      {'@type' => 'forward'},
      [
        config_element('server', '', {'host' => '127.0.0.1'}),
        config_element('secondary', '', {}, [
            config_element('server', '', {'host' => '192.168.1.2'}),
            config_element('server', '', {'host' => '192.168.1.3'})
          ]),
      ]
    )
    assert_nothing_raised do
      i.configure(conf)
    end
  end

  test 'when out_forward has @id' do
    # cancel https://github.com/fluent/fluentd/blob/077508ac817b7637307434d0c978d7cdc3d1c534/lib/fluent/plugin_id.rb#L43-L53
    # it always return true in test
    mock.proxy(Fluent::Plugin).new_sd('static', parent: anything) { |v|
      stub(v).plugin_id_for_test? { false }
    }.once

    output = Fluent::Test::Driver::Output.new(Fluent::Plugin::ForwardOutput) {
      def plugin_id_for_test?
        false
      end
    }

    assert_nothing_raised do
      output.configure(config + %[
        @id unique_out_forward
      ])
    end
  end

  sub_test_case 'verify_connection_at_startup' do
    test 'nodes are not available' do
      @d = d = create_driver(config + %[
        verify_connection_at_startup true
      ])
      e = assert_raise Fluent::UnrecoverableError do
        d.instance_start
      end
      if Fluent.windows?
        assert_match(/No connection could be made because the target machine actively refused it/, e.message)
      else
        assert_match(/Connection refused/, e.message)
      end

      d.instance_shutdown
    end

    test 'nodes_shared_key_miss_match' do
      input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                   </security>
                 ]
      target_input_driver = create_target_input_driver(conf: input_conf)
      output_conf = %[
        transport tcp
        verify_connection_at_startup true
        <security>
          self_hostname localhost
          shared_key key_miss_match
        </security>

        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]
      @d = d = create_driver(output_conf)

      target_input_driver.run(expect_records: 1, timeout: 1) do
        e = assert_raise Fluent::UnrecoverableError do
          d.instance_start
        end
        assert_match(/failed to establish connection/, e.message)
      end
    end

    test 'nodes_shared_key_miss_match with TLS' do
      input_conf = target_config + %[
                   <security>
                     self_hostname in.localhost
                     shared_key fluentd-sharedkey
                   </security>
                   <transport tls>
                     insecure true
                   </transport>
                 ]
      target_input_driver = create_target_input_driver(conf: input_conf)
      output_conf = %[
        transport tls
        tls_insecure_mode true
        verify_connection_at_startup true
        <security>
          self_hostname localhost
          shared_key key_miss_match
        </security>

        <server>
          host #{TARGET_HOST}
          port #{@target_port}
        </server>
      ]
      @d = d = create_driver(output_conf)

      target_input_driver.run(expect_records: 1, timeout: 1) do
        e = assert_raise Fluent::UnrecoverableError do
          d.instance_start
        end

        assert_match(/failed to establish connection/, e.message)
      end
    end

    test 'nodes_shared_key_match' do
      input_conf = target_config + %[
                       <security>
                         self_hostname in.localhost
                         shared_key fluentd-sharedkey
                       </security>
                     ]
      target_input_driver = create_target_input_driver(conf: input_conf)
      output_conf = %[
          verify_connection_at_startup true
          <security>
            self_hostname localhost
            shared_key fluentd-sharedkey
          </security>
          <server>
            name test
            host #{TARGET_HOST}
            port #{@target_port}
          </server>
      ]
      @d = d = create_driver(output_conf)

      time = event_time("2011-01-02 13:14:15 UTC")
      records = [{ "a" => 1 }, { "a" => 2 }]

      target_input_driver.run(expect_records: 2, timeout: 3) do
        d.run(default_tag: 'test') do
          records.each do |record|
            d.feed(time, record)
          end
        end
      end

      events = target_input_driver.events
      assert_false events.empty?
      assert_equal(['test', time, records[0]], events[0])
      assert_equal(['test', time, records[1]], events[1])
    end
  end

  test 'Create new connection per send_data' do
    target_input_driver = create_target_input_driver(conf: target_config)
    output_conf = config
    d = create_driver(output_conf)

    chunk = Fluent::Plugin::Buffer::MemoryChunk.new(Fluent::Plugin::Buffer::Metadata.new(nil, nil, nil))
    mock.proxy(d.instance).socket_create_tcp(TARGET_HOST, @target_port,
                                             linger_timeout: anything,
                                             send_timeout: anything,
                                             recv_timeout: anything,
                                             connect_timeout: anything
                                            ) { |sock| mock(sock).close.once; sock }.twice

    target_input_driver.run(timeout: 15) do
      d.run do
        node = d.instance.nodes.first
        2.times do
          node.send_data('test', chunk) rescue nil
        end
      end
    end
  end

  test 'if no available node' do
    # do not create output driver
    d = create_driver(%[
    <server>
      name test
      standby
      host #{TARGET_HOST}
      port #{@target_port}
    </server>
    ])
    assert_nothing_raised { d.run }
  end

  sub_test_case 'keepalive' do
    test 'Do not create connection per send_data' do
      target_input_driver = create_target_input_driver(conf: target_config)
      output_conf = config + %[
        keepalive true
        keepalive_timeout 2
      ]
      d = create_driver(output_conf)

      chunk = Fluent::Plugin::Buffer::MemoryChunk.new(Fluent::Plugin::Buffer::Metadata.new(nil, nil, nil))
      mock.proxy(d.instance).socket_create_tcp(TARGET_HOST, @target_port,
                                               linger_timeout: anything,
                                               send_timeout: anything,
                                               recv_timeout: anything,
                                               connect_timeout: anything
                                              ) { |sock| mock(sock).close.once; sock }.once

      target_input_driver.run(timeout: 15) do
        d.run do
          node = d.instance.nodes.first
          2.times do
            node.send_data('test', chunk) rescue nil
          end
        end
      end
    end

    test 'create timer of purging obsolete sockets' do
      output_conf = config + %[keepalive true]
      @d = d = create_driver(output_conf)

      mock(d.instance).timer_execute(:out_forward_heartbeat_request, 1).once
      mock(d.instance).timer_execute(:out_forward_keep_alived_socket_watcher, 5).once
      d.instance_start
    end

    sub_test_case 'with require_ack_response' do
      test 'Create connection per send_data' do
        target_input_driver = create_target_input_driver(conf: target_config)
        output_conf = config + %[
          require_ack_response true
          keepalive true
          keepalive_timeout 2
        ]
        d = create_driver(output_conf)

        chunk = Fluent::Plugin::Buffer::MemoryChunk.new(Fluent::Plugin::Buffer::Metadata.new(nil, nil, nil))
        mock.proxy(d.instance).socket_create_tcp(TARGET_HOST, @target_port,
                                                 linger_timeout: anything,
                                                 send_timeout: anything,
                                                 recv_timeout: anything,
                                                 connect_timeout: anything) { |sock|
          mock(sock).close.once; sock
        }.twice

        target_input_driver.run(timeout: 15) do
          d.run do
            node = d.instance.nodes.first
            2.times do
              node.send_data('test', chunk) rescue nil
            end
          end
        end
      end
    end
  end
end