Module: Fluent::ServerModule

Defined in:
lib/fluent/supervisor.rb

Instance Method Summary collapse

Instance Method Details

#after_run ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 92

def after_run
  stop_windows_event_thread if Fluent.windows?
  stop_rpc_server if @rpc_endpoint
  stop_counter_server if @counter
  cleanup_lock_dir
  Fluent::Supervisor.cleanup_socketmanager_path unless @starting_new_supervisor_with_zero_downtime
ensure
  notify_new_supervisor_that_old_one_has_stopped if @starting_new_supervisor_with_zero_downtime
end

#before_run ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 43

def before_run
  @fluentd_conf = config[:fluentd_conf]
  @rpc_endpoint = nil
  @rpc_server = nil
  @counter = nil
  @socket_manager_server = nil
  @starting_new_supervisor_with_zero_downtime = false
  @new_supervisor_pid = nil
  start_in_parallel = ENV.key?("FLUENT_RUNNING_IN_PARALLEL_WITH_OLD")
  @zero_downtime_restart_mutex = Mutex.new

  @fluentd_lock_dir = Dir.mktmpdir("fluentd-lock-")
  ENV['FLUENTD_LOCK_DIR'] = @fluentd_lock_dir

  if config[:rpc_endpoint] and not start_in_parallel
    @rpc_endpoint = config[:rpc_endpoint]
    @enable_get_dump = config[:enable_get_dump]
    run_rpc_server
  end

  if Fluent.windows?
    install_windows_event_handler
  else
    install_supervisor_signal_handlers
  end

  if counter = config[:counter_server] and not start_in_parallel
    run_counter_server(counter)
  end

  if config[:disable_shared_socket]
    $log.info "shared socket for multiple workers is disabled"
  elsif start_in_parallel
    begin
      raise "[BUG] SERVERENGINE_SOCKETMANAGER_PATH env var must exist when starting in parallel" unless ENV.key?('SERVERENGINE_SOCKETMANAGER_PATH')
      @socket_manager_server = ServerEngine::SocketManager::Server.share_sockets_with_another_server(ENV['SERVERENGINE_SOCKETMANAGER_PATH'])
      $log.info "zero-downtime-restart: took over the shared sockets", path: ENV['SERVERENGINE_SOCKETMANAGER_PATH']
    rescue => e
      $log.error "zero-downtime-restart: cancel sequence because failed to take over the shared sockets", error: e
      raise
    end
  else
    @socket_manager_server = ServerEngine::SocketManager::Server.open
    ENV['SERVERENGINE_SOCKETMANAGER_PATH'] = @socket_manager_server.path.to_s
  end

  stop_parallel_old_supervisor_after_delay if start_in_parallel
end

#cancel_source_only ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 439

def cancel_source_only
  if ENV.key?("FLUENT_RUNNING_IN_PARALLEL_WITH_OLD")
    if config[:rpc_endpoint]
      begin
        @rpc_endpoint = config[:rpc_endpoint]
        @enable_get_dump = config[:enable_get_dump]
        run_rpc_server
      rescue => e
        $log.error "failed to start RPC server", error: e
      end
    end

    if counter = config[:counter_server]
      begin
        run_counter_server(counter)
      rescue => e
        $log.error "failed to start counter server", error: e
      end
    end

    $log.info "zero-downtime-restart: done all sequences, now new processes start to work fully"
    ENV.delete("FLUENT_RUNNING_IN_PARALLEL_WITH_OLD")
  end

  send_signal_to_workers(:WINCH)
end

#cleanup_lock_dir ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 102

def cleanup_lock_dir
  begin
    Dir.each_child(@fluentd_lock_dir) do |name|
      FileUtils.rm_f(File.join(@fluentd_lock_dir, name)) if File.fnmatch?("fluentd-*.lock", name)
    end
  rescue Errno::ENOENT
    # Directory is already missing. Fall through and let rmdir below
    # fail in the same way as the current implementation.
  end
  FileUtils.rmdir(@fluentd_lock_dir)
end

#dump ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 508

def dump
  super unless @stop
end

#graceful_reload ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 365

def graceful_reload
  conf = nil
  t = Thread.new do
    $log.info 'Reloading new config'

    # Validate that loading config is valid at first
    conf = Fluent::Config.build(
      config_path: config[:config_path],
      encoding: config[:conf_encoding],
      additional_config: config[:inline_config],
      use_v1_config: config[:use_v1_config],
    )

    Fluent::VariableStore.try_to_reset do
      Fluent::Engine.reload_config(conf, supervisor: true)
    end
  end

  t.report_on_exception = false # Error is handled by myself
  t.join

  reopen_log
  send_signal_to_workers(:USR2)
  @fluentd_conf = conf.to_s
rescue => e
  $log.error "Failed to reload config file: #{e}"
end

#install_supervisor_signal_handlers ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 244

def install_supervisor_signal_handlers
  return if Fluent.windows?

  trap :HUP do
    $log.debug "fluentd supervisor process get SIGHUP"
    supervisor_sighup_handler
  end

  trap :USR1 do
    $log.debug "fluentd supervisor process get SIGUSR1"
    supervisor_sigusr1_handler
  end

  trap :USR2 do
    $log.debug 'fluentd supervisor process got SIGUSR2'
    if Fluent.windows?
      graceful_reload
    else
      zero_downtime_restart
    end
  end

  trap :WINCH do
    $log.debug 'fluentd supervisor process got SIGWINCH'
    cancel_source_only
  end
end

#install_windows_event_handler ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 290

def install_windows_event_handler
  return unless Fluent.windows?

  @pid_signame = "fluentd_#{Process.pid}"
  @signame = config[:signame]

  Thread.new do
    ipc = Win32::Ipc.new(nil)
    events = [
      {win32_event: Win32::Event.new("#{@pid_signame}_STOP_EVENT_THREAD"), action: :stop_event_thread},
      {win32_event: Win32::Event.new("#{@pid_signame}"), action: :stop},
      {win32_event: Win32::Event.new("#{@pid_signame}_HUP"), action: :hup},
      {win32_event: Win32::Event.new("#{@pid_signame}_USR1"), action: :usr1},
      {win32_event: Win32::Event.new("#{@pid_signame}_USR2"), action: :usr2},
      {win32_event: Win32::Event.new("#{@pid_signame}_CONT"), action: :cont},
    ]
    if @signame
      signame_events = [
        {win32_event: Win32::Event.new("#{@signame}"), action: :stop},
        {win32_event: Win32::Event.new("#{@signame}_HUP"), action: :hup},
        {win32_event: Win32::Event.new("#{@signame}_USR1"), action: :usr1},
        {win32_event: Win32::Event.new("#{@signame}_USR2"), action: :usr2},
        {win32_event: Win32::Event.new("#{@signame}_CONT"), action: :cont},
      ]
      events.concat(signame_events)
    end
    begin
      loop do
        infinite = 0xFFFFFFFF
        ipc_idx = ipc.wait_any(events.map {|e| e[:win32_event]}, infinite)
        event_idx = ipc_idx - 1

        if event_idx >= 0 && event_idx < events.length
          $log.debug("Got Win32 event \"#{events[event_idx][:win32_event].name}\"")
        else
          $log.warn("Unexpected return value of Win32::Ipc#wait_any: #{ipc_idx}")
        end
        case events[event_idx][:action]
        when :stop
          stop(true)
        when :hup
          supervisor_sighup_handler
        when :usr1
          supervisor_sigusr1_handler
        when :usr2
          graceful_reload
        when :cont
          supervisor_dump_handler_for_windows
        when :stop_event_thread
          break
        end
      end
    ensure
      events.each { |event| event[:win32_event].close }
    end
  end
end

#kill_worker ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 486

def kill_worker
  if config[:worker_pid]
    pids = config[:worker_pid].clone
    config[:worker_pid].clear
    pids.each_value do |pid|
      if Fluent.windows?
        Process.kill :KILL, pid
      else
        Process.kill :TERM, pid
      end
    end
  end
end

#notify_new_supervisor_that_old_one_has_stopped ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 225

def notify_new_supervisor_that_old_one_has_stopped
  if config[:pid_path]
    new_pid = File.read(config[:pid_path]).to_i
  else
    raise "[BUG] new_supervisor_pid is not saved" unless @new_supervisor_pid
    new_pid = @new_supervisor_pid
  end

  $log.info "zero-downtime-restart: notify the new supervisor (pid: #{new_pid}) that old one has stopped"
  Process.kill :WINCH, new_pid
rescue => e
  $log.error(
    "zero-downtime-restart: failed to notify the new supervisor." +
    " Please send SIGWINCH to the new supervisor process manually" +
    " if it does not start to work fully.",
    error: e
  )
end

#reload ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 283

def reload
  @monitors.each do |m|
    m.send_command("RELOAD\n")
  end
end

#restart(graceful) ⇒ Object

Override some methods of ServerEngine::MultiSpawnWorker Since Fluentd's Supervisor doesn't use ServerEngine's HUP, USR1 and USR2 handlers (see install_supervisor_signal_handlers), they should be disabled also on Windows, just send commands to workers instead.



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# File 'lib/fluent/supervisor.rb', line 277

def restart(graceful)
  @monitors.each do |m|
    m.send_command(graceful ? "GRACEFUL_RESTART\n" : "IMMEDIATE_RESTART\n")
  end
end

#run_counter_server(counter_conf) ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 194

def run_counter_server(counter_conf)
  @counter = Fluent::Counter::Server.new(
    counter_conf.scope,
    {host: counter_conf.bind, port: counter_conf.port, log: $log, path: counter_conf.backup_path}
  )
  @counter.start
end

#run_rpc_server ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 114

def run_rpc_server
  @rpc_server = RPC::Server.new(@rpc_endpoint, $log)

  # built-in RPC for signals
  @rpc_server.mount_proc('/api/processes.interruptWorkers') { |req, res|
    $log.debug "fluentd RPC got /api/processes.interruptWorkers request"
    Process.kill :INT, Process.pid
    nil
  }
  @rpc_server.mount_proc('/api/processes.killWorkers') { |req, res|
    $log.debug "fluentd RPC got /api/processes.killWorkers request"
    Process.kill :TERM, Process.pid
    nil
  }
  @rpc_server.mount_proc('/api/processes.flushBuffersAndKillWorkers') { |req, res|
    $log.debug "fluentd RPC got /api/processes.flushBuffersAndKillWorkers request"
    if Fluent.windows?
      supervisor_sigusr1_handler
      stop(true)
    else
      Process.kill :USR1, Process.pid
      Process.kill :TERM, Process.pid
    end
    nil
  }
  unless Fluent.windows?
    @rpc_server.mount_proc('/api/processes.zeroDowntimeRestart') { |req, res|
      $log.debug "fluentd RPC got /api/processes.zeroDowntimeRestart request"
      Process.kill :USR2, Process.pid
      nil
    }
  end
  @rpc_server.mount_proc('/api/plugins.flushBuffers') { |req, res|
    $log.debug "fluentd RPC got /api/plugins.flushBuffers request"
    if Fluent.windows?
      supervisor_sigusr1_handler
    else
      Process.kill :USR1, Process.pid
    end
    nil
  }
  @rpc_server.mount_proc('/api/config.reload') { |req, res|
    $log.debug "fluentd RPC got /api/config.reload request"
    if Fluent.windows?
      # restart worker with auto restarting by killing
      kill_worker
    else
      Process.kill :HUP, Process.pid
    end
    nil
  }
  @rpc_server.mount_proc('/api/config.dump') { |req, res|
    $log.debug "fluentd RPC got /api/config.dump request"
    $log.info "dump in-memory config"
    supervisor_dump_config_handler
    nil
  }

  @rpc_server.mount_proc('/api/config.gracefulReload') { |req, res|
    $log.debug "fluentd RPC got /api/config.gracefulReload request"
    graceful_reload
    nil
  }

  if @enable_get_dump
    @rpc_server.mount_proc('/api/config.getDump') { |req, res|
      $log.debug "fluentd RPC got /api/config.getDump request"
      $log.info "get dump in-memory config via HTTP"
      res.body = supervisor_get_dump_config_handler
      [nil, nil, res]
    }
  end

  @rpc_server.start
end

#stop_counter_server ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 202

def stop_counter_server
  @counter.stop
end

#stop_parallel_old_supervisor_after_delay ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 206

def stop_parallel_old_supervisor_after_delay
  Thread.new do
    # Delay to wait the new workers to start up.
    # Even if it takes a long time to start the new workers and stop the old Fluentd first,
    # it is no problem because the socket buffer works, as long as the capacity is not exceeded.
    sleep 10
    old_pid = ENV["FLUENT_RUNNING_IN_PARALLEL_WITH_OLD"]&.to_i
    if old_pid
      $log.info "zero-downtime-restart: stop the old supervisor"
      Process.kill :TERM, old_pid
    end
  rescue => e
    $log.warn "zero-downtime-restart: failed to stop the old supervisor." +
              " If the old one does not exist, please send SIGWINCH to this new process to start to work fully." +
              " If it exists, something went wrong. Please kill the old one manually.",
              error: e
  end
end

#stop_rpc_server ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 190

def stop_rpc_server
  @rpc_server&.shutdown
end

#stop_windows_event_thread ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 348

def stop_windows_event_thread
  if Fluent.windows?
    ev = Win32::Event.open("#{@pid_signame}_STOP_EVENT_THREAD")
    ev.set
    ev.close
  end
end

#supervisor_dump_config_handler ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 500

def supervisor_dump_config_handler
  $log.info @fluentd_conf
end

#supervisor_dump_handler_for_windows ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 466

def supervisor_dump_handler_for_windows
  # As for UNIX-like, SIGCONT signal to each process makes the process output its dump-file,
  # and it is implemented before the implementation of the function for Windows.
  # It is possible to trap SIGCONT and handle it here also on UNIX-like,
  # but for backward compatibility, this handler is currently for a Windows-only.
  raise "[BUG] This function is for Windows ONLY." unless Fluent.windows?

  Thread.new do
    begin
      FluentSigdump.dump_windows
    rescue => e
      $log.error "failed to dump: #{e}"
    end
  end

  send_signal_to_workers(:CONT)
rescue => e
  $log.error "failed to dump: #{e}"
end

#supervisor_get_dump_config_handler ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 504

def supervisor_get_dump_config_handler
  { conf: @fluentd_conf }
end

#supervisor_sighup_handler ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 356

def supervisor_sighup_handler
  kill_worker
end

#supervisor_sigusr1_handler ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 360

def supervisor_sigusr1_handler
  reopen_log
  send_signal_to_workers(:USR1)
end

#zero_downtime_restart ⇒ Object 



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# File 'lib/fluent/supervisor.rb', line 393

def zero_downtime_restart
  Thread.new do
    @zero_downtime_restart_mutex.synchronize do
      $log.info "start zero-downtime-restart sequence"

      if @starting_new_supervisor_with_zero_downtime
        $log.warn "zero-downtime-restart: canceled because it is already starting"
        Thread.exit
      end
      if ENV.key?("FLUENT_RUNNING_IN_PARALLEL_WITH_OLD")
        $log.warn "zero-downtime-restart: canceled because the previous sequence is still running"
        Thread.exit
      end

      @starting_new_supervisor_with_zero_downtime = true
      commands = [ServerEngine.ruby_bin_path, $0] + ARGV
      env_to_add = {
        "SERVERENGINE_SOCKETMANAGER_INTERNAL_TOKEN" => ServerEngine::SocketManager::INTERNAL_TOKEN,
        "FLUENT_RUNNING_IN_PARALLEL_WITH_OLD" => "#{Process.pid}",
      }
      pid = Process.spawn(env_to_add, commands.join(" "))
      @new_supervisor_pid = pid unless config[:daemonize]

      if config[:daemonize]
        Thread.new(pid) do |pid|
          _, status = Process.wait2(pid)
          # check if `ServerEngine::Daemon#daemonize_with_double_fork` succeeded or not
          unless status.success?
            @starting_new_supervisor_with_zero_downtime = false
            $log.error "zero-downtime-restart: failed because new supervisor exits unexpectedly"
          end
        end
      else
        Thread.new(pid) do |pid|
          _, status = Process.wait2(pid)
          @starting_new_supervisor_with_zero_downtime = false
          $log.error "zero-downtime-restart: failed because new supervisor exits unexpectedly", status: status
        end
      end
    end
  rescue => e
    $log.error "zero-downtime-restart: failed", error: e
    @starting_new_supervisor_with_zero_downtime = false
  end
end