fluent/fluentd · error · ArgumentError

invalid protocol: #{proto}

Error message

invalid protocol: #{proto}

What it means

Error "invalid protocol: #{proto}" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/plugin_helper/socket.rb:52

      include Fluent::PluginHelper::SocketOption

      attr_reader :_sockets # for tests

      # TODO: implement connection pool for specified host

      def socket_create(proto, host, port, **kwargs, &block)
        case proto
        when :tcp
          socket_create_tcp(host, port, **kwargs, &block)
        when :udp
          socket_create_udp(host, port, **kwargs, &block)
        when :tls
          socket_create_tls(host, port, **kwargs, &block)
        when :unix
          raise "not implemented yet"
        else
          raise ArgumentError, "invalid protocol: #{proto}"
        end
      end

      def socket_create_tcp(host, port, resolve_name: false, connect_timeout: nil, **kwargs, &block)
        sock = if connect_timeout
                 s = ::Socket.tcp(host, port, connect_timeout: connect_timeout)
                 s.autoclose = false # avoid GC triggered close
                 WrappedSocket::TCP.for_fd(s.fileno)
               else
                 WrappedSocket::TCP.new(host, port)
               end
        socket_option_set(sock, resolve_name: resolve_name, **kwargs)
        if block
          begin
            block.call(sock)
          ensure
            sock.close_write rescue nil
            sock.close rescue nil

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/plugin_helper/socket.rb:52 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of fluent/fluentd@dd45c6e18d (2026-08-21). Data as JSON: /api/errors/8dc8d1b0ef594efd. Report an issue: GitHub.