fluent/fluentd · error · Fluent::ConfigError

host '#{client.host}' cannot be resolved

Error message

host '#{client.host}' cannot be resolved

What it means

Error "host '#{client.host}' cannot be resolved" thrown in fluent/fluentd.

Source

Thrown at lib/fluent/plugin/in_forward.rb:148

        if !@security.allow_anonymous_source && @security.clients.empty?
          raise Fluent::ConfigError, "<client> sections required if allow_anonymous_source disabled"
        end

        @nodes = []

        @security.clients.each do |client|
          if client.host && client.network
            raise Fluent::ConfigError, "both of 'host' and 'network' are specified for client"
          end
          if !client.host && !client.network
            raise Fluent::ConfigError, "Either of 'host' and 'network' must be specified for client"
          end
          source = nil
          if client.host
            begin
              source = IPSocket.getaddress(client.host)
            rescue SocketError
              raise Fluent::ConfigError, "host '#{client.host}' cannot be resolved"
            end
          end
          source_addr = begin
                          IPAddr.new(source || client.network)
                        rescue ArgumentError
                          raise Fluent::ConfigError, "network '#{client.network}' address format is invalid"
                        end
          @nodes.push({
              address: source_addr,
              shared_key: (client.shared_key || @security.shared_key),
              users: client.users
            })
        end
      end

      if @send_keepalive_packet && @deny_keepalive
        raise Fluent::ConfigError, "both 'send_keepalive_packet' and 'deny_keepalive' cannot be set to true"
      end

View on GitHub (pinned to dd45c6e18d)

When it happens

Trigger: Thrown at lib/fluent/plugin/in_forward.rb:148 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/2fa6641d6335b4cd. Report an issue: GitHub.